文章
Dummer. ゛☀
2017年09月18日
Espostoa is a genus of columnar cacti, comprising 16 species known from the Andes of southern Ecuador and Peru. It usually lives at an altitude of between 2625 and 8200 feet (800 and 2500 m). Its fruit is edible, sweet, and juicy. The genus is named after Nicolas E. Esposto, a renowned botanist from Lima.
Espostoa are columnar cacti that mostly branch at the base to form a series of stems reminiscent of a big city skyline. The most notable feature of Espostoa is presence in most species of dense, white “hair” which quite dramatically covers the stems giving them a soft, fuzzy appearance. This is just an illusion however, as underneath the soft hairs are numerous sharp spines arranged on many small ribs which circle the columns. In some species the main central spine extends well past the hair making their threatening presence obvious.
Another trait of Espostoa that is seen in sexually mature stems is the flower-bearing lateral cephalium. This is an area along the sides of the stems that produce and especially dense wool and/or bristles out of which the flowers are produced. These structures are brown or gray or white and look as if something was smeared along one side of the stem. The flowers produced are cup or bell shaped and are typically 1 to 2 inches (2.5 to 5 cm) in diameter. Flowers are mostly white or rarely reddish and nocturnal.
Growing Conditions and General Care
Several species of Espostoa, are especially popular in cultivation due to their fuzzy white hairy appearance. The plants are typically sold by large commercial growers as up to 12 inch (30 cm) stems. However, being large columnar species, these plants do not grow nearly as vigorously in pots as they would in the ground. Plants tend to quickly fill the pots becoming pot bound and then growth slows to a crawl. As such, these plants rarely, if ever reach maturity meaning they don’t produce the cephalium and subsequently do not flower. On the other hand, those in warmer climates that can plant the species directly in the ground may indeed have plants that form a nice grouping of stems that will eventually flower.
Like all cacti, Espostoa requires a sunny location and well-drained soil. But in summer, it appreciates fertilizer and wetter conditions. In winter, it needs a rest, but the temperature must not drop below 54°F (12°C).
They are appreciated for their decorative qualities due to their white fleece.
Propagation
Espostoa can be successfully propagated by both vegetative cuttings and from seed. The seeds are quite easy to germinate and grow. Their main requirements consist of high humidity levels, free-draining soil mix, and enough water, light, and nutrition.
Espostoa are columnar cacti that mostly branch at the base to form a series of stems reminiscent of a big city skyline. The most notable feature of Espostoa is presence in most species of dense, white “hair” which quite dramatically covers the stems giving them a soft, fuzzy appearance. This is just an illusion however, as underneath the soft hairs are numerous sharp spines arranged on many small ribs which circle the columns. In some species the main central spine extends well past the hair making their threatening presence obvious.
Another trait of Espostoa that is seen in sexually mature stems is the flower-bearing lateral cephalium. This is an area along the sides of the stems that produce and especially dense wool and/or bristles out of which the flowers are produced. These structures are brown or gray or white and look as if something was smeared along one side of the stem. The flowers produced are cup or bell shaped and are typically 1 to 2 inches (2.5 to 5 cm) in diameter. Flowers are mostly white or rarely reddish and nocturnal.
Growing Conditions and General Care
Several species of Espostoa, are especially popular in cultivation due to their fuzzy white hairy appearance. The plants are typically sold by large commercial growers as up to 12 inch (30 cm) stems. However, being large columnar species, these plants do not grow nearly as vigorously in pots as they would in the ground. Plants tend to quickly fill the pots becoming pot bound and then growth slows to a crawl. As such, these plants rarely, if ever reach maturity meaning they don’t produce the cephalium and subsequently do not flower. On the other hand, those in warmer climates that can plant the species directly in the ground may indeed have plants that form a nice grouping of stems that will eventually flower.
Like all cacti, Espostoa requires a sunny location and well-drained soil. But in summer, it appreciates fertilizer and wetter conditions. In winter, it needs a rest, but the temperature must not drop below 54°F (12°C).
They are appreciated for their decorative qualities due to their white fleece.
Propagation
Espostoa can be successfully propagated by both vegetative cuttings and from seed. The seeds are quite easy to germinate and grow. Their main requirements consist of high humidity levels, free-draining soil mix, and enough water, light, and nutrition.
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文章
Dummer. ゛☀
2017年09月18日
The genus Aztekium contains three species of small globular cacti native to a small region in the Mexican Sierra Madre. Discovered in 1929 by F. Ritter, this genus was thought to be monotypic (with Aztekium ritteri) until a second species (Aztekium hintonii) was discovered by George S. Hinton in 1991. A further species, Aztekium valdesii, was discovered in 2011 by M.A. Alvarado Vázquez in the Sierra Madre Oriental mountains.
The genus name is dedicated to the Aztec people, due to the resemblance between the plant’s shape and certain Aztec sculptures.
Aztekium only grows in cracks in steep cliff faces filled with gypsum or limestone gravel and silt. The plants can look quite gnarly in the wild but carefully cultivated specimens are quite beautiful. Aztekium species offset slowly but generously in cultivation.
Growing Conditions and General Care
Aztekium are by far the most challenging and difficult cacti to grow. They are having extremely slow growth, probably the slowest of the entire cactus family. They usually take several years for growth to be even noticeable. Once a specimen is established on its own roots it is no trouble to keep it, and becomes an easy plant to manage.
Because of the difficulty of cultivation, Aztekiums are most often grafted to hardier stock. They need good drainage and regular water in summer. Water carefully from below in summer and keep nearly totally dry in winter. If grafted the plants can take a little more water. Just remember the graft stock is also a cactus and will rot if over watered. Provide shade from midday through the afternoon. A little morning sun is OK. If successful you’ll have tiny, white or pale pink, funnel-shaped flowers atop the plants intermittently throughout the spring and summer.
Propagation
They are usually propagated by seeds. The seeds are extremely fine and germinate readily, but the seed germination rate is very low (less than 5%).
The genus name is dedicated to the Aztec people, due to the resemblance between the plant’s shape and certain Aztec sculptures.
Aztekium only grows in cracks in steep cliff faces filled with gypsum or limestone gravel and silt. The plants can look quite gnarly in the wild but carefully cultivated specimens are quite beautiful. Aztekium species offset slowly but generously in cultivation.
Growing Conditions and General Care
Aztekium are by far the most challenging and difficult cacti to grow. They are having extremely slow growth, probably the slowest of the entire cactus family. They usually take several years for growth to be even noticeable. Once a specimen is established on its own roots it is no trouble to keep it, and becomes an easy plant to manage.
Because of the difficulty of cultivation, Aztekiums are most often grafted to hardier stock. They need good drainage and regular water in summer. Water carefully from below in summer and keep nearly totally dry in winter. If grafted the plants can take a little more water. Just remember the graft stock is also a cactus and will rot if over watered. Provide shade from midday through the afternoon. A little morning sun is OK. If successful you’ll have tiny, white or pale pink, funnel-shaped flowers atop the plants intermittently throughout the spring and summer.
Propagation
They are usually propagated by seeds. The seeds are extremely fine and germinate readily, but the seed germination rate is very low (less than 5%).
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文章
Dummer. ゛☀
2017年09月18日
Conifer sawflies are a unique group of defoliating insects. The various species (see "Pine Sawfly – Species") are distributed throughout the area where their preferred hosts grow. The larvae are hostspecific and feed on old and current year foliage at some point in their development. Some species have one generation per year with defoliation occurring in the spring and others produce three or more generations with defoliation occurring on into fall. Fall defoliation has a greater impact on trees and it is for this reason that sawflies having multiple generations are considered more devastating.
Sawfly adults resemble large houseflies but are actually primitive broad-waisted wasps. While true flies have one pair of wings, the sawfly has two pairs of wings. The females are equipped with an ovipositor that is serrated, which enables them to saw little slits in the needles where eggs are laid, thus the name "sawflies".
Defoliation by sawflies is sporadic, occurring in localized or region-wide outbreaks lasting one or more years. Growth loss the year following a severe defoliation (greater than 75%) can average over 50% and mortality increases due to secondary invasion by bark beetles and pine sawyers.
European pine sawfly is the most common sawfly in Missouri.
Symptoms and Diagnosis
Sawfly larvae have the curious habit of raising their heads and tails in a threatening manner when disturbed. Overwintering eggs that have been deposited in the needles can be easily located after a heavy frost turns the egg-laying scar yellow. (See "Pine Sawfly – Species" for a detailed description of larvae.)
Life Cycle - European Pine Sawfly
In August to September, the adult European pine sawflies emerge from their cocoons to mate and lay eggs. Female sawflies emit a sex pheromone that helps the male locate females for mating purposes. Using her saw-like ovipositor to cut through the tough outer skin of the needle, the female sawfly deposits overwintering eggs in slits she makes in the needles. Each female may lay six to eight eggs in each of 10 to 12 needles, but this will vary by sawfly species. European pine sawflies overwinter in the egg stage.
The eggs hatch in April through May and the larvae may feed until mid-June. The larvae feed in groups or colonies, often with three or four larvae feeding on a single needle. Being small and having small mouth parts, they merely rasp off the epidermal cells from the needles, which removes the protective barrier against desiccation. Thus, needles become twisted and brown as they dry out and die. Dead needles are easily detectable when contrasted against the green or surrounding "healthy" needles. As the larvae grow, they remain together and feed from the tip of a needle to the base. The larvae feed on older foliage and move from branch to branch as they strip the needles. Mature larvae drop to the ground and spin tough, brown cocoons in the duff. A few larvae may pupate on the tree.
The above life cycle is for the European pine sawfly that only has one generation per year. The life cycle of those with more than one generation per year may vary slightly as some may overwinter in the ground in the pupae stage. Climate and latitude have a great bearing on the number of generations per year.
Integrated Pest Management Strategies
1. Maintain plant vigor. Dry weather and poor soil conditions encourage damage by sawflies, therefore, water during times of drought. Keep plants vigorous with a fertilizing program.
2. Natural controls. Several parasites have been introduced to control this pest. Native birds feed on the larvae. Rodents often eat the pupae in the soil. These agents are usually not adequate in urban settings.
3. Mechanical control —egg removal. If the needles containing overwintered eggs can be found before they hatch, they can be pulled off the plant and destroyed. Do not simply throw on the ground since young could still hatch from the eggs.
4. Mechanical control. Colonies of larvae can be easily removed by clipping off the infested branch. Place these branches in a plastic bag and destroy. Colonies can also be knocked off by sharply striking the infested branch. Crush the larvae or knock into a pail of soapy water. If few colonies are present, they can be controlled using these methods, but large infestations are better controlled by general spraying.
5.Insecticide. Several horticultural oils and insecticidal soaps are labeled for control of sawflies on ornamentals. These usually work well when the sawfly larvae are small, and thorough coverage of the colony can be achieved. Pesticides registered for use include acephate (Orthene), azadirachtin (Bio-Neem, Margosan-O), or carbaryl (Sevin).
Sawfly adults resemble large houseflies but are actually primitive broad-waisted wasps. While true flies have one pair of wings, the sawfly has two pairs of wings. The females are equipped with an ovipositor that is serrated, which enables them to saw little slits in the needles where eggs are laid, thus the name "sawflies".
Defoliation by sawflies is sporadic, occurring in localized or region-wide outbreaks lasting one or more years. Growth loss the year following a severe defoliation (greater than 75%) can average over 50% and mortality increases due to secondary invasion by bark beetles and pine sawyers.
European pine sawfly is the most common sawfly in Missouri.
Symptoms and Diagnosis
Sawfly larvae have the curious habit of raising their heads and tails in a threatening manner when disturbed. Overwintering eggs that have been deposited in the needles can be easily located after a heavy frost turns the egg-laying scar yellow. (See "Pine Sawfly – Species" for a detailed description of larvae.)
Life Cycle - European Pine Sawfly
In August to September, the adult European pine sawflies emerge from their cocoons to mate and lay eggs. Female sawflies emit a sex pheromone that helps the male locate females for mating purposes. Using her saw-like ovipositor to cut through the tough outer skin of the needle, the female sawfly deposits overwintering eggs in slits she makes in the needles. Each female may lay six to eight eggs in each of 10 to 12 needles, but this will vary by sawfly species. European pine sawflies overwinter in the egg stage.
The eggs hatch in April through May and the larvae may feed until mid-June. The larvae feed in groups or colonies, often with three or four larvae feeding on a single needle. Being small and having small mouth parts, they merely rasp off the epidermal cells from the needles, which removes the protective barrier against desiccation. Thus, needles become twisted and brown as they dry out and die. Dead needles are easily detectable when contrasted against the green or surrounding "healthy" needles. As the larvae grow, they remain together and feed from the tip of a needle to the base. The larvae feed on older foliage and move from branch to branch as they strip the needles. Mature larvae drop to the ground and spin tough, brown cocoons in the duff. A few larvae may pupate on the tree.
The above life cycle is for the European pine sawfly that only has one generation per year. The life cycle of those with more than one generation per year may vary slightly as some may overwinter in the ground in the pupae stage. Climate and latitude have a great bearing on the number of generations per year.
Integrated Pest Management Strategies
1. Maintain plant vigor. Dry weather and poor soil conditions encourage damage by sawflies, therefore, water during times of drought. Keep plants vigorous with a fertilizing program.
2. Natural controls. Several parasites have been introduced to control this pest. Native birds feed on the larvae. Rodents often eat the pupae in the soil. These agents are usually not adequate in urban settings.
3. Mechanical control —egg removal. If the needles containing overwintered eggs can be found before they hatch, they can be pulled off the plant and destroyed. Do not simply throw on the ground since young could still hatch from the eggs.
4. Mechanical control. Colonies of larvae can be easily removed by clipping off the infested branch. Place these branches in a plastic bag and destroy. Colonies can also be knocked off by sharply striking the infested branch. Crush the larvae or knock into a pail of soapy water. If few colonies are present, they can be controlled using these methods, but large infestations are better controlled by general spraying.
5.Insecticide. Several horticultural oils and insecticidal soaps are labeled for control of sawflies on ornamentals. These usually work well when the sawfly larvae are small, and thorough coverage of the colony can be achieved. Pesticides registered for use include acephate (Orthene), azadirachtin (Bio-Neem, Margosan-O), or carbaryl (Sevin).
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文章
Dummer. ゛☀
2017年09月18日
There are approximately 140 North American species of lace bugs. Most have a specific host preference, which aids in identification. Some of the important species of lace bugs are for the azalea - Stephanitis pyrioides, hawthorn - Corythucha cydoniae, lantana - Teleonemia scrupulosa, and hackberry - C. celtidis. Lace bugs also feed on oak, elm, basswood, fringetree, and pyracantha among others.
The different species of adults vary from 1/8 to 3/8 inch in length but all have wings and thorax beautifully sculptured with an intricate pattern of veins that resembles lace. The nymphs are dark and are pointed at both ends. Lace bugs, both immature and adults, are most often found on the underside of leaves.
The London plane tree, Platanus acerifolia, is more susceptible to the lace bug than the sycamore, Plantanus occidentalis; both are hosts to the same species of lace bug.
Symptoms and Diagnosis
If heavily infested, the leaves may turn yellow and fall from trees and shrubs. The lace bug feeding mechanism is one that pierces and sucks the plant juices from leaves. This leaves tiny chlorotic flecks on the upper leaf surface. The underside of the leaves will have adults and spiny, dark-colored nymphs. The underside of leaves will look dirty with dark-brown spots and stains. When disturbed, lace bugs exhibit a peculiar bouncing movement.
Life Cycle
Female lace bugs lay groups of eggs on the underside of leaves most often along the midrib. These eggs are partially inserted into the leaf tissue and are pale and almost completely hidden inside the leaf. Many species secrete a brownish substance that hardens over the eggs and secures them to the leaf. Dark spiny nymphs hatch from the eggs and go through 5 to 6 nymphal instars before reaching adulthood. A complete life cycle takes only 30 to 40 days; several generations may occur each year. Lace bugs are more prevalent in late summer and fall. In late summer, both adults and nymphs will be feeding at the same time. Some species overwinter as eggs in the leaf or bark crevices or similar protected areas while other species overwinter in the adult stage.
Integrated Pest Management Strategies
1. Live with the insects but maintain plant vigor. In many cases, the damage occurs late enough in the season or is minor enough not to require action. Keeping plants healthy by watering during periods of drought will limit any damage caused by the insects.
2. Select planting areas carefully. Plant susceptible species away from sidewalks and lawns as dropping leaves, twigs, and lace bug excrement can be bad enough to be considered unpleasant.
3. Spray with water. Nymphs can be dislodged by forceful sprays of water and are vulnerable to control by contact with insecticidal soaps.
4. Sanitation. Prompt removal of leaves and twigs under plants can remove overwintering pests and limit the chances of reinfestation.
5. Control. Natural enemies are usually effective in maintaining populations at a low level and bringing outbreaks under control. Chemical controls are usually only used on shade and ornamental trees. Control of the azalea lace bug on evergreen azaleas is often required as the loss of leaves on these plants can have a more serious impact on plant health.
6. Use insecticides. Pesticides registered for use include acephate (Orthene), bendiocarb (Turcam, Closure), capsaicin, carbaryl (Sevin), disulfoton (Di-syston), malathion, permethrin, pyrethrins, and horticultural oils. Spray as soon as eggs hatch on leaves in early spring. Some control is possible with a dormant spray applied just before growth in spring.
The different species of adults vary from 1/8 to 3/8 inch in length but all have wings and thorax beautifully sculptured with an intricate pattern of veins that resembles lace. The nymphs are dark and are pointed at both ends. Lace bugs, both immature and adults, are most often found on the underside of leaves.
The London plane tree, Platanus acerifolia, is more susceptible to the lace bug than the sycamore, Plantanus occidentalis; both are hosts to the same species of lace bug.
Symptoms and Diagnosis
If heavily infested, the leaves may turn yellow and fall from trees and shrubs. The lace bug feeding mechanism is one that pierces and sucks the plant juices from leaves. This leaves tiny chlorotic flecks on the upper leaf surface. The underside of the leaves will have adults and spiny, dark-colored nymphs. The underside of leaves will look dirty with dark-brown spots and stains. When disturbed, lace bugs exhibit a peculiar bouncing movement.
Life Cycle
Female lace bugs lay groups of eggs on the underside of leaves most often along the midrib. These eggs are partially inserted into the leaf tissue and are pale and almost completely hidden inside the leaf. Many species secrete a brownish substance that hardens over the eggs and secures them to the leaf. Dark spiny nymphs hatch from the eggs and go through 5 to 6 nymphal instars before reaching adulthood. A complete life cycle takes only 30 to 40 days; several generations may occur each year. Lace bugs are more prevalent in late summer and fall. In late summer, both adults and nymphs will be feeding at the same time. Some species overwinter as eggs in the leaf or bark crevices or similar protected areas while other species overwinter in the adult stage.
Integrated Pest Management Strategies
1. Live with the insects but maintain plant vigor. In many cases, the damage occurs late enough in the season or is minor enough not to require action. Keeping plants healthy by watering during periods of drought will limit any damage caused by the insects.
2. Select planting areas carefully. Plant susceptible species away from sidewalks and lawns as dropping leaves, twigs, and lace bug excrement can be bad enough to be considered unpleasant.
3. Spray with water. Nymphs can be dislodged by forceful sprays of water and are vulnerable to control by contact with insecticidal soaps.
4. Sanitation. Prompt removal of leaves and twigs under plants can remove overwintering pests and limit the chances of reinfestation.
5. Control. Natural enemies are usually effective in maintaining populations at a low level and bringing outbreaks under control. Chemical controls are usually only used on shade and ornamental trees. Control of the azalea lace bug on evergreen azaleas is often required as the loss of leaves on these plants can have a more serious impact on plant health.
6. Use insecticides. Pesticides registered for use include acephate (Orthene), bendiocarb (Turcam, Closure), capsaicin, carbaryl (Sevin), disulfoton (Di-syston), malathion, permethrin, pyrethrins, and horticultural oils. Spray as soon as eggs hatch on leaves in early spring. Some control is possible with a dormant spray applied just before growth in spring.
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文章
Dummer. ゛☀
2017年09月18日
Bagworms, Thyridopteryx ephemeraeformis, produce conspicuous spindle-shaped cocoons on trees and shrubs throughout the United States. Bagworms feed on over 128 plant species. The most commonly attacked plants are arborvitae, red cedar, and other juniper species. They will also feed on fir, maple, juneberry, buckeye, persimmon, ginkgo, honeylocust, larch, sweet gum, spruce, pine, sycamore, poplar, oak, locust, willow, and hemlock.
Symptoms and Diagnosis
The principle harm done by the insect is the destruction of foliage by the caterpillars. Plants usually are partially defoliated, weakened, and rendered unsightly. Complete defoliation can occur. The most notable sign of bagworm infestation is the presence of protective bags attached to a branch. The bags incorporate bits of twigs and leaves from the host plant. They are approximately 1 to 2 inches long and resemble Christmas tree ornaments hanging from the limbs.
Life Cycle
The adult female bagworm does not look like a moth and never leaves her bag. She is maggot-like in appearance, soft-bodied, and yellowish-white. A mated female lays between 500 and 1000 eggs within the bag, after which she dies. The eggs remain inside the bag throughout the winter until they hatch the following spring. There is one generation a year.
From late May to mid-June, bagworm larvae (caterpillars) begin emerging from the bags. Almost immediately after emerging, a larva starts to produce its own protective bag. The bag is constructed such that the larva's head and legs are free. This construction allows the larvae to move about the plant as it feeds on the foliage. As the larva grows, it increases the size of its bag. The full-grown larvae are about one inch long.
When a host plant becomes defoliated, the larvae will crawl off it with their bags and search for a new plant to feed upon. In mid-August, the mature larvae stop feeding and attach their bags to a twig. They close up the bag and pupate. By mid-September, the bagworm has completed its development, and adult males begin emerging from their bags. The male moth has a black, furry body and feathery antennae. The wings are almost transparent and have a span of about one inch.
Integrated Pest Management Strategies
1. Handpick the bags. The most economical method of controlling bagworms is to handpick the bags and destroy them. Some birds and insect predators feed on larvae, so light infestations on large, healthy plants are usually controlled by natural means. On large plants, monitor infestations before resorting to chemical sprays. If the problem doesn't get worse, spraying is not required.
2. Use biological controls. In spring, as soon as eggs hatch and the young emerge, spray with Bacillus thuringiensis (Bt). Bt is a bacterium that causes the larvae to become sick, stop feeding, and later die. In St. Louis, the eggs hatch in late May to mid-June, or about the time the cigar tree, Catalpa speciosa, is in full bloom.
3. Use chemical controls. Because bagworms form protective bags very early, contact insecticides, while useful, are less effective than stomach poisons. For best control, spray when insects are young. Chemical controls become less effective as the bagworm matures. Chemical controls include acephate (Orthene), cyfluthrin and spinosad.
Symptoms and Diagnosis
The principle harm done by the insect is the destruction of foliage by the caterpillars. Plants usually are partially defoliated, weakened, and rendered unsightly. Complete defoliation can occur. The most notable sign of bagworm infestation is the presence of protective bags attached to a branch. The bags incorporate bits of twigs and leaves from the host plant. They are approximately 1 to 2 inches long and resemble Christmas tree ornaments hanging from the limbs.
Life Cycle
The adult female bagworm does not look like a moth and never leaves her bag. She is maggot-like in appearance, soft-bodied, and yellowish-white. A mated female lays between 500 and 1000 eggs within the bag, after which she dies. The eggs remain inside the bag throughout the winter until they hatch the following spring. There is one generation a year.
From late May to mid-June, bagworm larvae (caterpillars) begin emerging from the bags. Almost immediately after emerging, a larva starts to produce its own protective bag. The bag is constructed such that the larva's head and legs are free. This construction allows the larvae to move about the plant as it feeds on the foliage. As the larva grows, it increases the size of its bag. The full-grown larvae are about one inch long.
When a host plant becomes defoliated, the larvae will crawl off it with their bags and search for a new plant to feed upon. In mid-August, the mature larvae stop feeding and attach their bags to a twig. They close up the bag and pupate. By mid-September, the bagworm has completed its development, and adult males begin emerging from their bags. The male moth has a black, furry body and feathery antennae. The wings are almost transparent and have a span of about one inch.
Integrated Pest Management Strategies
1. Handpick the bags. The most economical method of controlling bagworms is to handpick the bags and destroy them. Some birds and insect predators feed on larvae, so light infestations on large, healthy plants are usually controlled by natural means. On large plants, monitor infestations before resorting to chemical sprays. If the problem doesn't get worse, spraying is not required.
2. Use biological controls. In spring, as soon as eggs hatch and the young emerge, spray with Bacillus thuringiensis (Bt). Bt is a bacterium that causes the larvae to become sick, stop feeding, and later die. In St. Louis, the eggs hatch in late May to mid-June, or about the time the cigar tree, Catalpa speciosa, is in full bloom.
3. Use chemical controls. Because bagworms form protective bags very early, contact insecticides, while useful, are less effective than stomach poisons. For best control, spray when insects are young. Chemical controls become less effective as the bagworm matures. Chemical controls include acephate (Orthene), cyfluthrin and spinosad.
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文章
Dummer. ゛☀
2017年09月18日
The pinewood nematode, Bursaphelenchus xylophilus, kills conifers, especially pines, of many species. This pest is endemic throughout the eastern half of the United States. Scotch pine (Scots pine) is the most commonly affected host. The nematode is transmitted by sawyer beetles, a wood-boring bark beetle, through their feeding wounds into the resin canals. Here, the nematode will reproduce and hinder the movement of water through water-conducting tissues, eventually causing the plant to wilt. Locally destructive outbreaks have occurred in forest and landscape plantings of non-native pine species in Missouri and Illinois.
Symptoms and Diagnosis
Early symptoms of pine wilt are often inconspicuous or slight, giving way to a rapid decline. The first visible symptoms usually include fading green color and/or slight yellowing of limbs. This may be evident on one or a few branches or may develop on all simultaneously. In addition, within 48 hours after infection, there will be a visible loss of resin flow as observed on a cut twig. Trees often die so rapidly that brown needles continue to cling to the twigs. Diseased pines commonly die in early summer or early fall; some species require 2 seasons. Confirmation of the disease is done by microscopic detection of the pathogenic nematode in an examination of infested wood samples from the main trunk or affected branches. For diagnostic purposes, branch samples should be not be less that one inch in diameter and collected from freshly killed areas where needles are brown, but still attached.
Life Cycle
Once a susceptible host plant has been inoculated with the pinewood nematode via bark beetle feeding, the nematode will feed and multiply in the resin canals. Populations of 1,000 nematodes per gram of wood may occur when foliar symptoms appear. When plant stress factors, such as high temperatures, drought, or attack by other pathogens, increase, nematode populations will rise. After the host plant dies, the nematode will transform into a non-feeding form and this stage can be picked up by wood-feeding bark beetle larvae. This dispersive stage of the nematode will migrate to the pupal chambers of the bark beetle, then enter the bodies of newly formed bark beetle adults that will seek other tree hosts, and repeat the nematodes’ life cycle.
Integrated Pest Management Strategies
1. Removal. Quick removal of an infected tree is important in order to break the nematodes’ life cycle. Infested wood should be burned or buried (not chipped and used as mulch) to prevent reproduction and overwintering of the bark beetles in infested wood. Periods of high temperatures in summer favor epidemics, as do periods of severe drought, but little else is known of factors that favor or prevent epidemics of pine wilt.
2. Select resistant varieties. Consistent with geography and climate, select evergreen trees that are more resistant to the pinewood nematode. These would include eastern hemlock; blue, Norway and Serbian spruce; and Jeffrey, pitch, Virginia, shortleaf, loblolly, and Eastern white pine. Avoid the more susceptible species such as Scotch pine (Scots pine), Austrian pine, Japanese black pine, Japanese red pine, jack pine, mugo pine, and long-leaf pine.
3. Maintain healthy trees. While even a healthy tree may become infested with the pinewood nematode, stressed trees are more attractive to bark beetle feeding. Watering during extended drought periods, periodic light fertilization, and avoiding damage to the root system through construction or traffic will all reduce the chances of borer infestation and nematode transmission.
Symptoms and Diagnosis
Early symptoms of pine wilt are often inconspicuous or slight, giving way to a rapid decline. The first visible symptoms usually include fading green color and/or slight yellowing of limbs. This may be evident on one or a few branches or may develop on all simultaneously. In addition, within 48 hours after infection, there will be a visible loss of resin flow as observed on a cut twig. Trees often die so rapidly that brown needles continue to cling to the twigs. Diseased pines commonly die in early summer or early fall; some species require 2 seasons. Confirmation of the disease is done by microscopic detection of the pathogenic nematode in an examination of infested wood samples from the main trunk or affected branches. For diagnostic purposes, branch samples should be not be less that one inch in diameter and collected from freshly killed areas where needles are brown, but still attached.
Life Cycle
Once a susceptible host plant has been inoculated with the pinewood nematode via bark beetle feeding, the nematode will feed and multiply in the resin canals. Populations of 1,000 nematodes per gram of wood may occur when foliar symptoms appear. When plant stress factors, such as high temperatures, drought, or attack by other pathogens, increase, nematode populations will rise. After the host plant dies, the nematode will transform into a non-feeding form and this stage can be picked up by wood-feeding bark beetle larvae. This dispersive stage of the nematode will migrate to the pupal chambers of the bark beetle, then enter the bodies of newly formed bark beetle adults that will seek other tree hosts, and repeat the nematodes’ life cycle.
Integrated Pest Management Strategies
1. Removal. Quick removal of an infected tree is important in order to break the nematodes’ life cycle. Infested wood should be burned or buried (not chipped and used as mulch) to prevent reproduction and overwintering of the bark beetles in infested wood. Periods of high temperatures in summer favor epidemics, as do periods of severe drought, but little else is known of factors that favor or prevent epidemics of pine wilt.
2. Select resistant varieties. Consistent with geography and climate, select evergreen trees that are more resistant to the pinewood nematode. These would include eastern hemlock; blue, Norway and Serbian spruce; and Jeffrey, pitch, Virginia, shortleaf, loblolly, and Eastern white pine. Avoid the more susceptible species such as Scotch pine (Scots pine), Austrian pine, Japanese black pine, Japanese red pine, jack pine, mugo pine, and long-leaf pine.
3. Maintain healthy trees. While even a healthy tree may become infested with the pinewood nematode, stressed trees are more attractive to bark beetle feeding. Watering during extended drought periods, periodic light fertilization, and avoiding damage to the root system through construction or traffic will all reduce the chances of borer infestation and nematode transmission.
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Dummer. ゛☀
2017年09月18日
Pine needle rusts are caused by over 20 species of Coleosporium the most common being C. asterum. It results in browning needles and the loss of lower branches. It is rare in the St. Louis area but may affect Austrian, jack, red, Scots, mugo, and ponderosa pines.
Symptoms and Diagnosis
The first sign of the disease is small yellow spots on the needles in fall and throughout the winter. In spring the spots develop spore-producing structures and the needles brown and die resulting in needle drop and the loss of lower limbs. Young pines are most affected.
Life Cycle
Pine needle rust requires an alternate host to complete its life cycle. Goldenrod and asters are most common. Infection on pine needles begins in late summer or early fall when spores released from the fungus growing on goldenrod or asters infects the needles causing small yellow spots. The fungus grows inside the needle where it overwinters. The following spring the fungus resumes growth and the yellow spots develop into white swelling, which grow well above the needle surface. At this time the disease may be confused with pine needle scale. The spore-producing structures split open and release orange colored spores, which then infect goldenrod and asters nearby. The fungus continues to produce spores that re-infect the alternate host until late in the season when spores that infect pine needles are formed, thus completing the rust’s life cycle. The life cycle is completed in one year.
Integrated Pest Management Strategies
1. Live with the disease. Pine needle rusts do very little damage to mature established trees. Young trees or trees grown in a nursery may require more aggressive action.
2. Remove the alternate host. Pine needle rust needs both pine needles and an alternate host of goldenrod or asters to complete its life cycle. Removing these alternate hosts near pines that suffer from the rust disease can break the cycle.
3. Plant resistant species. Replace susceptible pines with Colorado or Norway spruce. White pine is resistant but is not an ideal choice for the St. Louis area.
Symptoms and Diagnosis
The first sign of the disease is small yellow spots on the needles in fall and throughout the winter. In spring the spots develop spore-producing structures and the needles brown and die resulting in needle drop and the loss of lower limbs. Young pines are most affected.
Life Cycle
Pine needle rust requires an alternate host to complete its life cycle. Goldenrod and asters are most common. Infection on pine needles begins in late summer or early fall when spores released from the fungus growing on goldenrod or asters infects the needles causing small yellow spots. The fungus grows inside the needle where it overwinters. The following spring the fungus resumes growth and the yellow spots develop into white swelling, which grow well above the needle surface. At this time the disease may be confused with pine needle scale. The spore-producing structures split open and release orange colored spores, which then infect goldenrod and asters nearby. The fungus continues to produce spores that re-infect the alternate host until late in the season when spores that infect pine needles are formed, thus completing the rust’s life cycle. The life cycle is completed in one year.
Integrated Pest Management Strategies
1. Live with the disease. Pine needle rusts do very little damage to mature established trees. Young trees or trees grown in a nursery may require more aggressive action.
2. Remove the alternate host. Pine needle rust needs both pine needles and an alternate host of goldenrod or asters to complete its life cycle. Removing these alternate hosts near pines that suffer from the rust disease can break the cycle.
3. Plant resistant species. Replace susceptible pines with Colorado or Norway spruce. White pine is resistant but is not an ideal choice for the St. Louis area.
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文章
Dummer. ゛☀
2017年09月18日
Dothistroma blight is a foliar disease of a number of pine species throughout the Midwest. Austrian pine is the primary host plant in Missouri. This blight is caused by the fungus Dothistroma pini, which infects and kills needles. The disease makes pines in landscapes unsightly and successive years of infection can result in decline and death of the tree.
Symptoms and Diagnosis
The earliest observable symptoms are dark-green bands and tan spots or bands on the mature needles. The spots and bands later turn reddish-brown. The needles will begin to die back from the tip, but needle bases usually remain green. From the time symptoms are first noticed to the time of needle browning may take 2–3 weeks. Infected needles will drop prematurely. Infection typically is most severe in the lower crown of the tree, closer to the inoculum that spreads from infected needles that have fallen from the tree.
Life Cycle
Dothistroma overwinters in infected needles. The infective spores are released during wet weather and dispersed by rain splash throughout the growing season. Because of the continual release of spores, infections can occur anytime from late April to late October. The fungus attacks the mature foliage; current season's needles are resistant until they are fully mature. Symptoms on newly infected tissue are especially obvious in early fall.
Integrated Pest Management Strategies
1. Live with the disease but monitor yearly. This disease is slow to spread. Annual spraying is not necessary in residential plantings. Wait and see how serious the problem becomes in one season. Serious infections can be prevented in the next growing season with the use of fungicides.
2. Plant resistant pines.Research on Austrian pine has determined that some populations are highly resistant to Dothistroma. Ask for these at your local garden center or nursery. Choose other nonsusceptible evergreens.
3. Apply fungicides. Adequate control of Dothistroma blight can be achieved with one or two sprays in late spring using a copper-based fungicides such as Bordeaux mixture. The first spray in early to mid-May protects mature foliage. A second spray in mid- June will protect the current season's needles which are resistant until they are fully grown. Other protectant fungicides include chlorothalonil (Daconil), Mancozeb and pentachloronitrobenzene.
Symptoms and Diagnosis
The earliest observable symptoms are dark-green bands and tan spots or bands on the mature needles. The spots and bands later turn reddish-brown. The needles will begin to die back from the tip, but needle bases usually remain green. From the time symptoms are first noticed to the time of needle browning may take 2–3 weeks. Infected needles will drop prematurely. Infection typically is most severe in the lower crown of the tree, closer to the inoculum that spreads from infected needles that have fallen from the tree.
Life Cycle
Dothistroma overwinters in infected needles. The infective spores are released during wet weather and dispersed by rain splash throughout the growing season. Because of the continual release of spores, infections can occur anytime from late April to late October. The fungus attacks the mature foliage; current season's needles are resistant until they are fully mature. Symptoms on newly infected tissue are especially obvious in early fall.
Integrated Pest Management Strategies
1. Live with the disease but monitor yearly. This disease is slow to spread. Annual spraying is not necessary in residential plantings. Wait and see how serious the problem becomes in one season. Serious infections can be prevented in the next growing season with the use of fungicides.
2. Plant resistant pines.Research on Austrian pine has determined that some populations are highly resistant to Dothistroma. Ask for these at your local garden center or nursery. Choose other nonsusceptible evergreens.
3. Apply fungicides. Adequate control of Dothistroma blight can be achieved with one or two sprays in late spring using a copper-based fungicides such as Bordeaux mixture. The first spray in early to mid-May protects mature foliage. A second spray in mid- June will protect the current season's needles which are resistant until they are fully grown. Other protectant fungicides include chlorothalonil (Daconil), Mancozeb and pentachloronitrobenzene.
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Dummer. ゛☀
2017年09月17日
Anacampseros is a genus consisting of a several species of small perennial succulent plants native to South Africa. The botanical name is an ancient one for herbs supposed to restore lost love. All form basal rosettes of smooth or hairy leaves in dense mats and develop a small caudex with age. White filamentous hairs are present along the stems. The wheel-shaped flowers vary from white to purple. The plants are self-fertile and produce seeds in a cup of upright filaments. They are dormant in winter.
Growing Conditions and General Care
Anacampseros grow well in partial sun with bright light enhancing the leaf colors and keeping them compact. They require a gritty free-draining soil with added organic material and low to moderate watering. The beautiful caudiciform species are prone to rot and should be watered very sparingly. Feed with a high potassium fertilizer in summer during the growing season diluted to one-fourth potency and mix into the watering can for application. Anacampseros is an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame. It do well outdoors in raised beds and terraces as well.
Anacampseros crinita
Anacampseros may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, watch carefully for any significant decline in health. This may signal a pest problem that should be dealt with quickly in order to prevent scarring, stunting and even death.
Repotting
Repot Anacampseros once a year in order to evaluate the health of the plant and provide a larger growing space being careful not to damage the sensitive roots.
Propagation
Anacampseros are easy to propagate either through stem cuttings or seed.
Growing Conditions and General Care
Anacampseros grow well in partial sun with bright light enhancing the leaf colors and keeping them compact. They require a gritty free-draining soil with added organic material and low to moderate watering. The beautiful caudiciform species are prone to rot and should be watered very sparingly. Feed with a high potassium fertilizer in summer during the growing season diluted to one-fourth potency and mix into the watering can for application. Anacampseros is an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame. It do well outdoors in raised beds and terraces as well.
Anacampseros crinita
Anacampseros may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, watch carefully for any significant decline in health. This may signal a pest problem that should be dealt with quickly in order to prevent scarring, stunting and even death.
Repotting
Repot Anacampseros once a year in order to evaluate the health of the plant and provide a larger growing space being careful not to damage the sensitive roots.
Propagation
Anacampseros are easy to propagate either through stem cuttings or seed.
3
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文章
Dummer. ゛☀
2017年09月17日
Maihuenia is a genus largely accepted as containing two species which are quite distinct from other cactus. The plants in this genus are so different that they have been classified as the sole genus in the subfamily Maihuenioideae.
These plants grow as mats which hug the ground and are made up of segmented short-rounded stems. The stems feature typically 3 spines per areole and also have small rounded leaves which do not fall off as they do in Opuntias. The flowers come from the ends of the stems and are shades of yellow from near-white to orange. Club-shaped fruits are fleshy and contain bracts.
The natural habitat of this species is in the region known as Patagonia in the southern parts of Argentina and Chile at elevations of 8,000 feet (2450 m) elevation. In this harsh environment, these cacti commonly endure frost and are starting to become sought by cold-hardy cactus growers in North America.
Growing Condition and General Care
Maihuenia is an easy-to-grow plant. It can survive outside in the garden in the sunny rockery on a sheltered place, but only if it’s protected with a sheet of glass during the wintertime. It is also very good for a large pot which can be stored inside an unheated greenhouse or on a balcony, somewhat protected from moisture during the winter, but is probably safest to grow it in the Alpine House or in a raised bed inside an unheated greenhouse all year around, with lots of ventilation. They should not be kept hot in summer as they are from high elevations.
During the growing season it’s good to enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen.
For a balanced development, it is best to place it in a position where it is exposed at least a few hours of direct sunlight.
Water these plants only from time to time if grown outdoors, but it should be watered abundantly if grown in a pot or in the greenhouse, during the summer.
The spring weather, with a high temperature swing between the day and night hours, and pretty frequent rains, can favor the development of fungus diseases, which should be treated with a systemic fungicide. Repot it every 2 to 3 years.
These plants grow as mats which hug the ground and are made up of segmented short-rounded stems. The stems feature typically 3 spines per areole and also have small rounded leaves which do not fall off as they do in Opuntias. The flowers come from the ends of the stems and are shades of yellow from near-white to orange. Club-shaped fruits are fleshy and contain bracts.
The natural habitat of this species is in the region known as Patagonia in the southern parts of Argentina and Chile at elevations of 8,000 feet (2450 m) elevation. In this harsh environment, these cacti commonly endure frost and are starting to become sought by cold-hardy cactus growers in North America.
Growing Condition and General Care
Maihuenia is an easy-to-grow plant. It can survive outside in the garden in the sunny rockery on a sheltered place, but only if it’s protected with a sheet of glass during the wintertime. It is also very good for a large pot which can be stored inside an unheated greenhouse or on a balcony, somewhat protected from moisture during the winter, but is probably safest to grow it in the Alpine House or in a raised bed inside an unheated greenhouse all year around, with lots of ventilation. They should not be kept hot in summer as they are from high elevations.
During the growing season it’s good to enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen.
For a balanced development, it is best to place it in a position where it is exposed at least a few hours of direct sunlight.
Water these plants only from time to time if grown outdoors, but it should be watered abundantly if grown in a pot or in the greenhouse, during the summer.
The spring weather, with a high temperature swing between the day and night hours, and pretty frequent rains, can favor the development of fungus diseases, which should be treated with a systemic fungicide. Repot it every 2 to 3 years.
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文章
Dummer. ゛☀
2017年09月17日
There are nearly 5,000 different species of rust of which about 10 may be important pathogens on turfgrass. They attack only live grass plants, and two or more rusts may attack the same grass plant at the same time. Different races of the pathogens occur and they differ in their ability to attack cultivars (varieties) within a grass genus or species. This is one of the reasons that some grass cultivars lose their rust resistance after being grown for a period of years.
Rusts in the genus Pucciniaoccur on all commonly grown warm- and cool-season turfgrasses, and a few are responsible for significant stand losses. Among warm-season turfgrasses, zoysiagrass lawns are often the target of severe rust damage, while bermudagrass, St. Augustine grass, and centipede grass lawns are far less likely to suffer serious injury. Perennial ryegrass is the most susceptible of commonly grown cool-season turfgrasses, but the disease is rare on tall fescue and bentgrass. With few exceptions, the host range of rust fungi is limited to a few turfgrasses.
Symptoms and Diagnosis
Diseased plants initially develop light yellow flecks on the leaves. As the spots enlarge, the surfaces of the leaves rupture, exposing masses of powdery, brick red spores. Continuous heavy infection causes many grass blades to turn yellow, wither, and die. A severely rusted lawn may winterkill. From a distance, rust-infected turf appears dull yellow or light brown. Individual plants may die and the turf becomes noticeably thin. The disease tends to be more severe in partially shaded areas, such as under trees or along fences.
Life Cycle
The cycle of development for the rust fungus is very complex because of the many species involved and the numerous alternate hosts, mostly woody shrubs and herbaceous ornamentals. Alternate hosts are not believed to play an important role in the disease development of the fungi that attack turf grasses.
The rust fungi may overwinter in infected plants or be reintroduced into lawns each summer by windblown spores. Each spore must come in contact with a water droplet on the leaf or stem surface to germinate and infect the plant. Infection of leaf blades is favored by moderate temperatures (68 degrees to 85 degrees F) and extended wet periods. This cycle is repeated about every two weeks under conditions favorable for rust development.
Integrated Pest Management Strategies
1. Fertilizer. Use a balanced fertilizer at recommended levels, according to a soil test. Low nitrogen levels and nutrient imbalance can encourage rust.
2. Mowing. Mow regularly to remove infected leaf blades before the spores are produced. Avoid mowing lower that the recommended height, as this can lead to stunted root systems and decrease the ability of the turf to withstand drought.
3. Watering. Water early in the day to allow the leaves to dry before night. Avoid water stress by irrigating during dry periods.
4. Cultivars. Select resistant cultivars. Before seeding, consider recommended cultivars that are resistant to rusts.
Organic Strategies
Strategies 2, 3 and 4 are strictly organic approaches. Using an appropriate organic fertilizer would be a viable organic approach to Strategy 1.
Rusts in the genus Pucciniaoccur on all commonly grown warm- and cool-season turfgrasses, and a few are responsible for significant stand losses. Among warm-season turfgrasses, zoysiagrass lawns are often the target of severe rust damage, while bermudagrass, St. Augustine grass, and centipede grass lawns are far less likely to suffer serious injury. Perennial ryegrass is the most susceptible of commonly grown cool-season turfgrasses, but the disease is rare on tall fescue and bentgrass. With few exceptions, the host range of rust fungi is limited to a few turfgrasses.
Symptoms and Diagnosis
Diseased plants initially develop light yellow flecks on the leaves. As the spots enlarge, the surfaces of the leaves rupture, exposing masses of powdery, brick red spores. Continuous heavy infection causes many grass blades to turn yellow, wither, and die. A severely rusted lawn may winterkill. From a distance, rust-infected turf appears dull yellow or light brown. Individual plants may die and the turf becomes noticeably thin. The disease tends to be more severe in partially shaded areas, such as under trees or along fences.
Life Cycle
The cycle of development for the rust fungus is very complex because of the many species involved and the numerous alternate hosts, mostly woody shrubs and herbaceous ornamentals. Alternate hosts are not believed to play an important role in the disease development of the fungi that attack turf grasses.
The rust fungi may overwinter in infected plants or be reintroduced into lawns each summer by windblown spores. Each spore must come in contact with a water droplet on the leaf or stem surface to germinate and infect the plant. Infection of leaf blades is favored by moderate temperatures (68 degrees to 85 degrees F) and extended wet periods. This cycle is repeated about every two weeks under conditions favorable for rust development.
Integrated Pest Management Strategies
1. Fertilizer. Use a balanced fertilizer at recommended levels, according to a soil test. Low nitrogen levels and nutrient imbalance can encourage rust.
2. Mowing. Mow regularly to remove infected leaf blades before the spores are produced. Avoid mowing lower that the recommended height, as this can lead to stunted root systems and decrease the ability of the turf to withstand drought.
3. Watering. Water early in the day to allow the leaves to dry before night. Avoid water stress by irrigating during dry periods.
4. Cultivars. Select resistant cultivars. Before seeding, consider recommended cultivars that are resistant to rusts.
Organic Strategies
Strategies 2, 3 and 4 are strictly organic approaches. Using an appropriate organic fertilizer would be a viable organic approach to Strategy 1.
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文章
Dummer. ゛☀
2017年09月17日
Brown patch (Rhizoctonia solani) is a fungus which attacks most commonly cultivated grasses. Differences in susceptibility exists within cultivars of the various grass species. Bent grass, perennial ryegrass, tall fescue and annual bluegrass are the primary hosts. There are various species of Rhizoctonia which can attack grass plants from seedling stage too mature plants and are pathogenic over a wide range of environmental conditions.
Brown patch may also be referred to as Rhizoctonia blight. Large brown patch is used to describe the disease in zoysiagrass.
Symptoms and Diagnosis
Symptoms vary depending on the turfgrass species and mowing height. Susceptibility of the cultivar, management practices and weather conditions determine the degree of injury. More than one fungi may also be present in the lawn.
As the name suggests, symptoms include small circular patches of brown, lifeless grass. These patches often enlarge and join together, reaching diameters of six feet or more. Newly established lawns may be more severely damaged than established lawns.
In warm-season grasses such as zoysia the most common symptom is a circular pattern of brown grass with a yellowish colored ring (smoke ring) of wilted grass at the perimeter of the diseased area. The leaves can easily be pulled from the stolons within the smoke ring because the fungus destroys the tissue at the base of the leaf sheath. First appearing symptoms are small circular patches of water-soaked dark grass that soon wilt and turn light brown. Stolons often remain green. As the disease develops, the circular patches enlarge, become more apparent and new green leaves may emerge in the center of the circular areas.
Life Cycle
Mid to late summer is the time when the best conditions are present for disease development. This requires the presence of an active fungi, vigorous growth of a susceptible grass, daytime temperatures ranges between 75 degrees and 85 degrees F, the presence of free moisture on the foliage and night temperatures below 68 degrees F. This fungus feeds on dead organic matter in the soil, but will attack grass when the right environmental conditions arise. Hot, humid conditions promote spread of the fungi.
Integrated Pest Management Strategies
1. Fertilizer. Don't fertilize warm-season grasses in early spring and summer, particularly with soluble nitrogen. Use slow-release nitrogen fertilizers. Fertilize to maintain adequate but not lush growth during the growing season. Properly fertilized turf will recover quicker from disease injury than will under-fertilized turf.
2. Collect waste. Remove and dispose of clippings from infected areas or when conditions are conducive to disease development. Mulching mowers that chop clippings to 1/4 inch or less do not contribute to brown patch development. Mow only when the grass is dry, being sure to remove no more than one third of the top growth.
3. Prune. Prune trees and shrubs to allow air movement and light penetration to reach the turfgrass.
4. Watering. Water to a depth of about 6 inches no more than once a week. More frequent watering provides an ideal environment for disease development.
5. Drainage. Provide good surface and subsurface water drainage to reduce humidity in the turf canopy.
6. Fungicide. Use a preventive fungicide program with recommended fungicides. Read labels for proper fungicides and their use.
7. Replant dead areas. The disease can occur quickly, spread rapidly and then stop abruptly as environmental conditions change. Frequently, the best and only recourse is to replant dead areas in warmseason lawns in early summer.
Organic Strategies
Strategies 2, 3, 4, 5 and 7 are strictly organic approaches. Using an appropriate organic fertilizer would be a viable organic approach to Strategy 1.
Brown patch may also be referred to as Rhizoctonia blight. Large brown patch is used to describe the disease in zoysiagrass.
Symptoms and Diagnosis
Symptoms vary depending on the turfgrass species and mowing height. Susceptibility of the cultivar, management practices and weather conditions determine the degree of injury. More than one fungi may also be present in the lawn.
As the name suggests, symptoms include small circular patches of brown, lifeless grass. These patches often enlarge and join together, reaching diameters of six feet or more. Newly established lawns may be more severely damaged than established lawns.
In warm-season grasses such as zoysia the most common symptom is a circular pattern of brown grass with a yellowish colored ring (smoke ring) of wilted grass at the perimeter of the diseased area. The leaves can easily be pulled from the stolons within the smoke ring because the fungus destroys the tissue at the base of the leaf sheath. First appearing symptoms are small circular patches of water-soaked dark grass that soon wilt and turn light brown. Stolons often remain green. As the disease develops, the circular patches enlarge, become more apparent and new green leaves may emerge in the center of the circular areas.
Life Cycle
Mid to late summer is the time when the best conditions are present for disease development. This requires the presence of an active fungi, vigorous growth of a susceptible grass, daytime temperatures ranges between 75 degrees and 85 degrees F, the presence of free moisture on the foliage and night temperatures below 68 degrees F. This fungus feeds on dead organic matter in the soil, but will attack grass when the right environmental conditions arise. Hot, humid conditions promote spread of the fungi.
Integrated Pest Management Strategies
1. Fertilizer. Don't fertilize warm-season grasses in early spring and summer, particularly with soluble nitrogen. Use slow-release nitrogen fertilizers. Fertilize to maintain adequate but not lush growth during the growing season. Properly fertilized turf will recover quicker from disease injury than will under-fertilized turf.
2. Collect waste. Remove and dispose of clippings from infected areas or when conditions are conducive to disease development. Mulching mowers that chop clippings to 1/4 inch or less do not contribute to brown patch development. Mow only when the grass is dry, being sure to remove no more than one third of the top growth.
3. Prune. Prune trees and shrubs to allow air movement and light penetration to reach the turfgrass.
4. Watering. Water to a depth of about 6 inches no more than once a week. More frequent watering provides an ideal environment for disease development.
5. Drainage. Provide good surface and subsurface water drainage to reduce humidity in the turf canopy.
6. Fungicide. Use a preventive fungicide program with recommended fungicides. Read labels for proper fungicides and their use.
7. Replant dead areas. The disease can occur quickly, spread rapidly and then stop abruptly as environmental conditions change. Frequently, the best and only recourse is to replant dead areas in warmseason lawns in early summer.
Organic Strategies
Strategies 2, 3, 4, 5 and 7 are strictly organic approaches. Using an appropriate organic fertilizer would be a viable organic approach to Strategy 1.
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文章
Dummer. ゛☀
2017年09月17日
Brown patch (Rhizoctonia solani) is a fungus which attacks most commonly cultivated grasses: bent grass, perennial ryegrass, tall fescue and annual bluegrass, but especially tall fescue. There are various species of Rhizoctonia which can attack grass plants from seedling stage too mature plants and are pathogenic over a wide range of environmental conditions. It is common in dense, highly fertilized turf.
Brown patch may also be referred to as Rhizoctonia blight. Large brown patch is used to describe the disease in zoysiagrass. Large Patch in Zoysia Lawns
Symptoms and Diagnosis
Symptoms vary depending on the turfgrass species and mowing height. Susceptibility of the cultivar, management practices and weather conditions determine the degree of injury. More than one fungi may also be present in the lawn.
As the name suggests, symptoms include small circular patches of brown, lifeless grass. These patches often enlarge and join together, reaching diameters of six feet or more. Newly established lawns may be more severely damaged than established lawns.
In cool-season grasses water soaked circular patches that range from a few inches to several feet in diameter appear. The affected leaves wilt and turn light brown, but remain upright. A dark, grayish-black ring (smoke ring) of wilted grass often is present around the perimeter of the diseased areas in the early morning.
Life Cycle
Disease development requires the presence of an active fungus, vigorous growth of a susceptible grass, daytime temperatures ranges between 75 degrees and 85 degrees F, the presence of free moisture on the foliage and night temperatures below 68 degrees F. This fungus feeds on dead organic matter in the soil, but will attack grass when the right environmental conditions arise. Hot, humid conditions promote spread of the fungi.
Integrated Pest Management Strategies
1. Fertilizer. Avoid heavy, early spring and summer fertilization, particularly with soluble nitrogen. Avoid over fertilization of turfgrasses growing in shaded areas. Use slow-release nitrogen fertilizers. Fertilize to maintain adequate but not lush growth during the growing season. Properly fertilized turf will recover quicker from disease injury than will under-fertilized turf.
2. Collect waste. Remove and dispose of clippings from infected areas or when conditions are conducive to disease development. Mulching mowers that chop clippings to 1/4 inch or less do not contribute to brown patch development. Mow only when the grass is dry, being sure to remove no more than one third of the top growth.
3. Prune. Prune trees and shrubs to allow air movement and light penetration to reach the turfgrass.
4. Watering. Water to a depth of about 6 inches no more than once a week. More frequent watering provides an ideal environment for disease development.
5. Drainage. Provide good surface and subsurface water drainage to reduce humidity in the turf canopy.
6. Fungicide. Use a preventive fungicide program with recommended fungicides. Read labels for proper fungicides and their use.
7. Replant dead areas. The disease can occur quickly, spread rapidly and then stop abruptly as environmental conditions change. Frequently, the best and only recourse is to replant dead areas at the proper time of year—early fall or spring.
Brown patch may also be referred to as Rhizoctonia blight. Large brown patch is used to describe the disease in zoysiagrass. Large Patch in Zoysia Lawns
Symptoms and Diagnosis
Symptoms vary depending on the turfgrass species and mowing height. Susceptibility of the cultivar, management practices and weather conditions determine the degree of injury. More than one fungi may also be present in the lawn.
As the name suggests, symptoms include small circular patches of brown, lifeless grass. These patches often enlarge and join together, reaching diameters of six feet or more. Newly established lawns may be more severely damaged than established lawns.
In cool-season grasses water soaked circular patches that range from a few inches to several feet in diameter appear. The affected leaves wilt and turn light brown, but remain upright. A dark, grayish-black ring (smoke ring) of wilted grass often is present around the perimeter of the diseased areas in the early morning.
Life Cycle
Disease development requires the presence of an active fungus, vigorous growth of a susceptible grass, daytime temperatures ranges between 75 degrees and 85 degrees F, the presence of free moisture on the foliage and night temperatures below 68 degrees F. This fungus feeds on dead organic matter in the soil, but will attack grass when the right environmental conditions arise. Hot, humid conditions promote spread of the fungi.
Integrated Pest Management Strategies
1. Fertilizer. Avoid heavy, early spring and summer fertilization, particularly with soluble nitrogen. Avoid over fertilization of turfgrasses growing in shaded areas. Use slow-release nitrogen fertilizers. Fertilize to maintain adequate but not lush growth during the growing season. Properly fertilized turf will recover quicker from disease injury than will under-fertilized turf.
2. Collect waste. Remove and dispose of clippings from infected areas or when conditions are conducive to disease development. Mulching mowers that chop clippings to 1/4 inch or less do not contribute to brown patch development. Mow only when the grass is dry, being sure to remove no more than one third of the top growth.
3. Prune. Prune trees and shrubs to allow air movement and light penetration to reach the turfgrass.
4. Watering. Water to a depth of about 6 inches no more than once a week. More frequent watering provides an ideal environment for disease development.
5. Drainage. Provide good surface and subsurface water drainage to reduce humidity in the turf canopy.
6. Fungicide. Use a preventive fungicide program with recommended fungicides. Read labels for proper fungicides and their use.
7. Replant dead areas. The disease can occur quickly, spread rapidly and then stop abruptly as environmental conditions change. Frequently, the best and only recourse is to replant dead areas at the proper time of year—early fall or spring.
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文章
Dummer. ゛☀
2017年09月17日
The fall webworm, Hyphantria cunea, is a general feeder on nearly all trees except conifers. While this native North American insect attacks over 100 different tree species, it tends to prefer mulberry, walnut, hickory, elm, sweetgum, poplar, willow, oak, linden, ash, apple, and other fruit trees. The insect makes webs at branch tips and is harmful mainly to the beauty of the host. It is considered to be more of a nuisance than a threat to the health of the tree.
Symptoms and Diagnosis
A distinctive web of silk, containing many caterpillars, is constructed around leaves at branch ends. Each "nest" may contain hundreds of larvae that feed together for a while. By late summer, the unsightly nest may measure three feet across and, in addition to the growing larvae, contains excrement, dried leaf fragments, and cast skins. An unusual characteristic of fall webworm caterpillars is that if alarmed, all the caterpillars in a nest make jerking movements in unison. It is thought that this is a potential defensive mechanism to startle and deter predators.
Another tent-forming caterpillar is the eastern tent caterpillar, Malacosoma americanum. However, eastern tent caterpillars make webbed silk nests in a fork of a branch or tree trunk and leave the nest to feed. Fall webworm caterpillars have nests at branch tips and feed inside the webbing.
Life Cycle
In late spring or early summer, adults emerge from overwintering pupal cases and lay hair-covered masses of several hundred eggs on the underside of leaves. The larvae that emerge can be either yellowish green with a black head or tan with a red head. Both color forms have many long, gray hairs and pairs of wart-like black spots running down their backs. Once feeding begins, the larvae congregate in masses and produce the silky web that surrounds the entire colony. Larvae feed inside the web and expand it as they grow. Larvae stay in the colony until their last molt after which they may be found crawling anywhere on the host plant. The larvae crawl to a protected place to spin a flimsy cocoon and pupate. The adults emerging from pupation have two color forms: either all white or white with black spots. There are two generations a year.
Integrated Pest Management Strategies
1. Live with the problem and let nature take its course. Hosts are seldom seriously harmed because defoliation usually occurs later in summer rather than during a period of active growth and not enough terminal growth is consumed to affect tree growth. In addition, more than 75 natural enemies parasitize and prey on the fall webworm.
2. Prune out webs. Branches that have active webs ("nests") may be cut out and destroyed. Webs are always on branch ends and are easier to remove when they are small. Pole pruners are helpful for reaching into trees.
3. Apply insecticidal sprays. If chemical control is truly necessary, treatment is recommended when webs first appear. This is because the smaller caterpillars are more susceptible to insecticides and, secondly, the webbed nests are somewhat waterproof and can be difficult to penetrate with sprays. The microbial insecticide Bt (Bacillus thuringiensis) is available as Dipel or Thuricide and can be used on the small caterpillars. Other pesticides registered for use include acephate (Orthene), carbaryl (Sevin), pyrethrins and spinosad.
Symptoms and Diagnosis
A distinctive web of silk, containing many caterpillars, is constructed around leaves at branch ends. Each "nest" may contain hundreds of larvae that feed together for a while. By late summer, the unsightly nest may measure three feet across and, in addition to the growing larvae, contains excrement, dried leaf fragments, and cast skins. An unusual characteristic of fall webworm caterpillars is that if alarmed, all the caterpillars in a nest make jerking movements in unison. It is thought that this is a potential defensive mechanism to startle and deter predators.
Another tent-forming caterpillar is the eastern tent caterpillar, Malacosoma americanum. However, eastern tent caterpillars make webbed silk nests in a fork of a branch or tree trunk and leave the nest to feed. Fall webworm caterpillars have nests at branch tips and feed inside the webbing.
Life Cycle
In late spring or early summer, adults emerge from overwintering pupal cases and lay hair-covered masses of several hundred eggs on the underside of leaves. The larvae that emerge can be either yellowish green with a black head or tan with a red head. Both color forms have many long, gray hairs and pairs of wart-like black spots running down their backs. Once feeding begins, the larvae congregate in masses and produce the silky web that surrounds the entire colony. Larvae feed inside the web and expand it as they grow. Larvae stay in the colony until their last molt after which they may be found crawling anywhere on the host plant. The larvae crawl to a protected place to spin a flimsy cocoon and pupate. The adults emerging from pupation have two color forms: either all white or white with black spots. There are two generations a year.
Integrated Pest Management Strategies
1. Live with the problem and let nature take its course. Hosts are seldom seriously harmed because defoliation usually occurs later in summer rather than during a period of active growth and not enough terminal growth is consumed to affect tree growth. In addition, more than 75 natural enemies parasitize and prey on the fall webworm.
2. Prune out webs. Branches that have active webs ("nests") may be cut out and destroyed. Webs are always on branch ends and are easier to remove when they are small. Pole pruners are helpful for reaching into trees.
3. Apply insecticidal sprays. If chemical control is truly necessary, treatment is recommended when webs first appear. This is because the smaller caterpillars are more susceptible to insecticides and, secondly, the webbed nests are somewhat waterproof and can be difficult to penetrate with sprays. The microbial insecticide Bt (Bacillus thuringiensis) is available as Dipel or Thuricide and can be used on the small caterpillars. Other pesticides registered for use include acephate (Orthene), carbaryl (Sevin), pyrethrins and spinosad.
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文章
Dummer. ゛☀
2017年09月17日
The eastern tent caterpillar, Malacosoma americanum, is a native species that occurs throughout the eastern United States and westward to the Rocky Mountains. Before the outbreak of the gypsy moth, the eastern tent caterpillar was considered by many authorities to be the most widespread and destructive defoliating pest of deciduous trees in the eastern United States. Its favorite host trees include apple, wild cherry, and crabapple. However, the caterpillars will also attack ash, birch, maple, oak, poplar, cherry, and plum. Populations fluctuate greatly because of factors such as unfavorable weather and natural enemies.
Symptoms and Diagnosis
Eggs are laid in distinctive masses encircling the twigs of the host plant. The egg masses are about 3/4 of an inch long and are covered with a dark substance that makes them appear varnished. The egg mass has the consistency of styrofoam. Eggs hatch and the caterpillars gather at a nearby branch fork where they begin to build a silk webbed tent. As the caterpillars grow, they build new tents in the larger forks of trees. Webbed tents are the most obvious sign of the caterpillars.
Another tent-forming caterpillar is the fall webworm, Hyphantria cunea. However, fall webworm caterpillars make webbed silk nests at the ends of branches and feed inside the nest. Eastern tent caterpillars have tents in a fork of a branch or tree trunk and they leave the nest to feed.
Life Cycle
Tent caterpillars overwinter as eggs in an egg mass. The eggs hatch in the spring, about the time wild cherry leaves begin to unfold. The young caterpillars quickly gather at a branch fork or crotch and begin to build a silk web. The larvae leave their tent to feed on foliage. Young caterpillars feed during the day and remain in the tent at night; older (and larger) caterpillars feed at night and remain in the tent during the day.
Mature larvae can reach a length of about 2 inches. They are generally black with a white stripe down the back and have a series of blue spots between yellow lines that run lengthwise down the back. They also have long, fine hairs all over their body. This is the only common caterpillar with a white stripe down the back. At maturity, a caterpillar will leave the host tree and search for a place to spin a cocoon (fence post, tree trunks, debris on the ground, sides of buildings, etc.). Adult moths emerge in two weeks, mate, and lay eggs that overwinter. Moths have reddish-brown wings with two white diagonal stripes on each front wing. There is one generation per year with about 9 months spent in the egg stage.
Integrated Pest Management Strategies
1. Live with the problem. It is not necessary to spray insecticides to control the eastern tent caterpillar. Healthy defoliated trees will grow new leaves. Infested trees can be unsightly and are less vigorous than attacked trees, but they are seldom killed. Typical natural controls include birds, predaceous and parasitic insects (especially wasps), and disease organisms. Caterpillars with white eggs or cocoons attached to their back should not be destroyed because they are being hosts for native parasites.
2. Handpick egg masses. Future damage on small trees can be reduced by locating and removing egg masses during winter because they are most obvious at that time. They can be scraped off with a thumbnail or pruned out.
3. Manual removal of tents or caterpillars. Start looking for tents when service berries (Amelanchier laevis) or sugar maples (Acer saccharum) are blooming or when silver maples (Acer saccharinum) have leaves about 1 to 2 inches long. Tents can be pruned off if small, because they are usually located in small branch forks. They can also be removed by winding them around the end of a broomstick or pole that has a small brush or nails mounted on the end. It is most effective to do this at night or on cloudy, rainy days because the young caterpillars are gathered in the tent for protection and aren't venturing out to feed. Caterpillars can also be handpicked and dropped into soapy water.
4. Apply insecticides. If insecticide sprays are necessary, they should be applied when the tents are first noticed. Caterpillars leave the tents to feed so thorough coverage of the foliage with the insecticidal spray will provide control. Tents are water repellent so spraying them with water based insecticides is not very effective. Insecticides that can be used include Bacillus thuringiensis (Bt, Dipel or Thuricide), carbaryl (Sevin), pyrethrins, acephate (Orthene) or spinosad.
Symptoms and Diagnosis
Eggs are laid in distinctive masses encircling the twigs of the host plant. The egg masses are about 3/4 of an inch long and are covered with a dark substance that makes them appear varnished. The egg mass has the consistency of styrofoam. Eggs hatch and the caterpillars gather at a nearby branch fork where they begin to build a silk webbed tent. As the caterpillars grow, they build new tents in the larger forks of trees. Webbed tents are the most obvious sign of the caterpillars.
Another tent-forming caterpillar is the fall webworm, Hyphantria cunea. However, fall webworm caterpillars make webbed silk nests at the ends of branches and feed inside the nest. Eastern tent caterpillars have tents in a fork of a branch or tree trunk and they leave the nest to feed.
Life Cycle
Tent caterpillars overwinter as eggs in an egg mass. The eggs hatch in the spring, about the time wild cherry leaves begin to unfold. The young caterpillars quickly gather at a branch fork or crotch and begin to build a silk web. The larvae leave their tent to feed on foliage. Young caterpillars feed during the day and remain in the tent at night; older (and larger) caterpillars feed at night and remain in the tent during the day.
Mature larvae can reach a length of about 2 inches. They are generally black with a white stripe down the back and have a series of blue spots between yellow lines that run lengthwise down the back. They also have long, fine hairs all over their body. This is the only common caterpillar with a white stripe down the back. At maturity, a caterpillar will leave the host tree and search for a place to spin a cocoon (fence post, tree trunks, debris on the ground, sides of buildings, etc.). Adult moths emerge in two weeks, mate, and lay eggs that overwinter. Moths have reddish-brown wings with two white diagonal stripes on each front wing. There is one generation per year with about 9 months spent in the egg stage.
Integrated Pest Management Strategies
1. Live with the problem. It is not necessary to spray insecticides to control the eastern tent caterpillar. Healthy defoliated trees will grow new leaves. Infested trees can be unsightly and are less vigorous than attacked trees, but they are seldom killed. Typical natural controls include birds, predaceous and parasitic insects (especially wasps), and disease organisms. Caterpillars with white eggs or cocoons attached to their back should not be destroyed because they are being hosts for native parasites.
2. Handpick egg masses. Future damage on small trees can be reduced by locating and removing egg masses during winter because they are most obvious at that time. They can be scraped off with a thumbnail or pruned out.
3. Manual removal of tents or caterpillars. Start looking for tents when service berries (Amelanchier laevis) or sugar maples (Acer saccharum) are blooming or when silver maples (Acer saccharinum) have leaves about 1 to 2 inches long. Tents can be pruned off if small, because they are usually located in small branch forks. They can also be removed by winding them around the end of a broomstick or pole that has a small brush or nails mounted on the end. It is most effective to do this at night or on cloudy, rainy days because the young caterpillars are gathered in the tent for protection and aren't venturing out to feed. Caterpillars can also be handpicked and dropped into soapy water.
4. Apply insecticides. If insecticide sprays are necessary, they should be applied when the tents are first noticed. Caterpillars leave the tents to feed so thorough coverage of the foliage with the insecticidal spray will provide control. Tents are water repellent so spraying them with water based insecticides is not very effective. Insecticides that can be used include Bacillus thuringiensis (Bt, Dipel or Thuricide), carbaryl (Sevin), pyrethrins, acephate (Orthene) or spinosad.
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