文章
Dummer. ゛☀
2017年09月17日
We have touched on specific ways to care for certain types of succulents in Ultimate Guide to Succulents: Types of Succulents. Some care instructions depend on your zone or whether the plant is outdoors or in a container. General guidelines for succulent care are below.
How Often To Water
Most succulents don’t need a lot of water. The general rule is to let the top half of the soil dry out before you water it again. In the summer, outdoor succulents generally need to be watered once a week. Water container plants two or three times a week.
You’ll usually reduce irrigation in lower temperatures even for indoor houseplants. However, different varieties of succulents require different amounts of water. Check with a local nursery or the company from which you bought the plant for specific watering instructions.
Propagating
Succulents are best grown from offsets or propagated leaves. If your plant sends out “pups”, you can remove those smaller “babies” and replant them.
You can also propagate the plants from leaves. Snap off a few of the lower leaves from the plant. To do this, hold the leaf close to the base. Wiggle and twist it until it separates from the stem. Choose healthy leaves, and propagate a few at a time. Not all of them will propagate. Leave the leaves in a cool, dry place for up to a week. The cut end should end up developing a hard callous that resembles a scab. Once that happens, you can begin to sprout new roots. Fill a shallow container with soil designed for potted succulents. Lay the leaves horizontally on top of the soil. The calloused end shouldn’t touch the soil.
Leave the container in indirect sunlight. Spray the top of the soil with water every day. It should be damp, but not wet. Don’t mist the soil if you live in a humid climate. In about a month, you’ll see roots growing from the cut end of the leaf toward the soil. You can lightly cover the roots with soil to prevent them from drying out. A miniature version of the plant will begin to grow upward from the cut end of the leaf. When that small plant develops its own root system and the original leaf begins to noticeably deteriorate, remove the leaf from the new plant in the same manner that you removed it from the mother plant. Be careful not to disturb the new roots. Replant the new succulent in its own pot. Use a small pot at first, and make sure to use cactus or succulent soil.
Soil
Succulents grow best in soil that drains well. Some types prefer nutrient-dense soil, but most do well as long as the soil isn’t too moist. Most garden stores sell soil that’s designed for cacti and succulents. If you’re growing succulents in containers, you can use a mix of equal parts sand, potting soil, and perlite. Outdoor succulents should be fed with a low-balanced fertilizer (10-10-10) in spring and late summer. Use about half the recommended ratio of fertilizer to water. Only fertilize when the soil is dry.
Sunlight
Nearly all succulents flourish with a lot of light. Your plants should get approximately six hours of direct sunlight every day. Depending on your planting zone and the plant type, you may need to shade your succulents during the hottest part of the day.
Indoor succulents should be placed near a window. However, they shouldn’t get burned by direct sunlight. Succulents are relatively resilient when it comes to their sunlight needs. Less light may cause the colors to become dull. The plants may not bloom without sufficient UV light. However, they will survive in many lighting conditions.
Where to Buy Succulents
Once you start looking for succulents, you’ll notice that they’re sold in many different places. A local supplier may be able to provide you with succulents that are better for your area. Succulent plant groups can provide you with cuttings, succulent seeds or mature plants. Local botanical gardens may also sell succulents.
Many garden shops, from large chain stores to smaller local nurseries, carry succulents. However, it may be difficult to find rare or unusual species here. Succulents sold in garden shops are often already potted.
Some of the most beautiful, unique and vibrant succulents are difficult to find locally. Thank goodness for the internet. Many online vendors will ship these plants directly to you. You can choose the specific variety that you purchase. You can also often get a discount if you buy large sets of mixed varieties. Buying succulents in bulk online may be preferable if you’re trying to fill up a vertical garden or a large space. The plants are often sold in plugs that you can replant in the final destination.
Succulents are not expensive. You can get plants for anywhere from $2 to $10 on average. The price is often determined by the size and rareness of the plant. You can get them even more affordably by trading with other growers, propagating the leaves or replanting offsets.
Succulents have become increasingly more popular due to their ease of maintenance and unique style. There is a wide range of succulents to choose from so you should not have any trouble finding one to match your garden or style. This succulent guide was put together to make sure you have all the information possible that you could need before you get started.
How Often To Water
Most succulents don’t need a lot of water. The general rule is to let the top half of the soil dry out before you water it again. In the summer, outdoor succulents generally need to be watered once a week. Water container plants two or three times a week.
You’ll usually reduce irrigation in lower temperatures even for indoor houseplants. However, different varieties of succulents require different amounts of water. Check with a local nursery or the company from which you bought the plant for specific watering instructions.
Propagating
Succulents are best grown from offsets or propagated leaves. If your plant sends out “pups”, you can remove those smaller “babies” and replant them.
You can also propagate the plants from leaves. Snap off a few of the lower leaves from the plant. To do this, hold the leaf close to the base. Wiggle and twist it until it separates from the stem. Choose healthy leaves, and propagate a few at a time. Not all of them will propagate. Leave the leaves in a cool, dry place for up to a week. The cut end should end up developing a hard callous that resembles a scab. Once that happens, you can begin to sprout new roots. Fill a shallow container with soil designed for potted succulents. Lay the leaves horizontally on top of the soil. The calloused end shouldn’t touch the soil.
Leave the container in indirect sunlight. Spray the top of the soil with water every day. It should be damp, but not wet. Don’t mist the soil if you live in a humid climate. In about a month, you’ll see roots growing from the cut end of the leaf toward the soil. You can lightly cover the roots with soil to prevent them from drying out. A miniature version of the plant will begin to grow upward from the cut end of the leaf. When that small plant develops its own root system and the original leaf begins to noticeably deteriorate, remove the leaf from the new plant in the same manner that you removed it from the mother plant. Be careful not to disturb the new roots. Replant the new succulent in its own pot. Use a small pot at first, and make sure to use cactus or succulent soil.
Soil
Succulents grow best in soil that drains well. Some types prefer nutrient-dense soil, but most do well as long as the soil isn’t too moist. Most garden stores sell soil that’s designed for cacti and succulents. If you’re growing succulents in containers, you can use a mix of equal parts sand, potting soil, and perlite. Outdoor succulents should be fed with a low-balanced fertilizer (10-10-10) in spring and late summer. Use about half the recommended ratio of fertilizer to water. Only fertilize when the soil is dry.
Sunlight
Nearly all succulents flourish with a lot of light. Your plants should get approximately six hours of direct sunlight every day. Depending on your planting zone and the plant type, you may need to shade your succulents during the hottest part of the day.
Indoor succulents should be placed near a window. However, they shouldn’t get burned by direct sunlight. Succulents are relatively resilient when it comes to their sunlight needs. Less light may cause the colors to become dull. The plants may not bloom without sufficient UV light. However, they will survive in many lighting conditions.
Where to Buy Succulents
Once you start looking for succulents, you’ll notice that they’re sold in many different places. A local supplier may be able to provide you with succulents that are better for your area. Succulent plant groups can provide you with cuttings, succulent seeds or mature plants. Local botanical gardens may also sell succulents.
Many garden shops, from large chain stores to smaller local nurseries, carry succulents. However, it may be difficult to find rare or unusual species here. Succulents sold in garden shops are often already potted.
Some of the most beautiful, unique and vibrant succulents are difficult to find locally. Thank goodness for the internet. Many online vendors will ship these plants directly to you. You can choose the specific variety that you purchase. You can also often get a discount if you buy large sets of mixed varieties. Buying succulents in bulk online may be preferable if you’re trying to fill up a vertical garden or a large space. The plants are often sold in plugs that you can replant in the final destination.
Succulents are not expensive. You can get plants for anywhere from $2 to $10 on average. The price is often determined by the size and rareness of the plant. You can get them even more affordably by trading with other growers, propagating the leaves or replanting offsets.
Succulents have become increasingly more popular due to their ease of maintenance and unique style. There is a wide range of succulents to choose from so you should not have any trouble finding one to match your garden or style. This succulent guide was put together to make sure you have all the information possible that you could need before you get started.
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ZENizJEN：2085158243
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
Whiteflies are common on houseplants and in greenhouses. They are piercing-sucking insects found on the underside of leaves. When disturbed on a heavily infested plant, a white cloud of adults will fly into the air. A large infestation can cause plant damage and loss of leaves. In most cases, it is more of a nuisance than a threat to the plant. Since homes and greenhouses are always warm, they can reproduce throughout the year.
When purchasing new plants, always check under the leaves making sure pests are not present. Also, check branching areas for pests. In the home make a habit of checking the underside of leaves when you water. They are easiest to remove at an early stage. In most cases, the pest will not be spotted until there are adults flying around the plant when they are disturbed.
Symptoms and Diagnosis
Identification of the whitefly is easy as an apparent white cloud of small snowflakes rises from foliage when disturbed. The adults are about 1/10 to 1/16 inch in length, wedge shaped, and moth-like with white, powdery wings.
Symptoms vary—infested leaves may show little, if any, symptoms or may be mottled and yellow. Leaves will also become coated with a sticky substance called honeydew that is secreted by feeding whitefly nymphs and adults. A black, sooty mold may sometimes grow on the honeydew. Sooty mold does not damage the leaf. The feeding, however, removes nutrients from the plant, resulting in stunting, poor growth, defoliation, reduced yields, and sometimes death.
Life Cycle
Whiteflies are closely related to scales, mealybugs, and aphids. They undergo complete metamorphosis with all life stages present at any time. Eggs are laid on the underside of the leaves. One female can lay about 200 to 400 eggs. They are usually laid in cigar- or circle-shaped clusters of 30 to 40 eggs. The eggs hatch in about a week into nymphs or crawlers. The crawlers wander about the plant and insert their mouth parts to feed on plant sap. When they molt, they lose their antennae and attach themselves to the underside of the leaves where they continue to feed until they pupate. Adults emerge and are about 1/10 to 1/16 inch long and look like a small white moth. The adult has four wings that are covered with a white, powdery, waxy substance. Within a population, all life stages are present, and generations often overlap. The life cycle takes only 18 days.
Integrated Pest Management Strategies
1. Inspection. Inspect all new plants brought indoors for whitefly. Inspect regularly, and remove by hand older leaves that are heavily infested with whiteflies in a non-mobile nymphal stage. Isolate new plants for a few days before placing them among other plants.
2. Mechanical control. The use of traps can be very helpful in controlling light infestations. Make yellow sticky traps about 12 x 6 inches and coat them with a sticky substance such as Tanglefoot, petroleum jelly, or heavy grade motor oil. Hang the traps vertically near the affected plants. The adults are attracted to yellow. Traps are also commercially available. One trap for every couple plants is recommended.
3. Chemical control. Whiteflies have developed resistance to some chemicals. Because of this resistance, a certain product may work well in one area but not in another. Resistance may be delayed by alternating the types of chemicals used. In addition, the egg and non-feeding pupa stages are generally not as susceptible to insecticides as are the adults and nymphs. Consequently, eradication of a whitefly population usually requires four to five applications of a registered insecticide at five to seven day intervals. Be sure the applications are made to the lower leaf surface, and apply as soon as whiteflies are detected. Do not wait until populations become severe.
Some of the over-the-counter chemicals that could be used contain permethrin or pyrethrins. Insecticidal soap, petroleum oil, and insect growth regulators can also be effective.
Before using any insecticide for whitefly control, make sure that the target plant is listed on the label and that the chemical is approved for use indoors. Follow label directions carefully.
When purchasing new plants, always check under the leaves making sure pests are not present. Also, check branching areas for pests. In the home make a habit of checking the underside of leaves when you water. They are easiest to remove at an early stage. In most cases, the pest will not be spotted until there are adults flying around the plant when they are disturbed.
Symptoms and Diagnosis
Identification of the whitefly is easy as an apparent white cloud of small snowflakes rises from foliage when disturbed. The adults are about 1/10 to 1/16 inch in length, wedge shaped, and moth-like with white, powdery wings.
Symptoms vary—infested leaves may show little, if any, symptoms or may be mottled and yellow. Leaves will also become coated with a sticky substance called honeydew that is secreted by feeding whitefly nymphs and adults. A black, sooty mold may sometimes grow on the honeydew. Sooty mold does not damage the leaf. The feeding, however, removes nutrients from the plant, resulting in stunting, poor growth, defoliation, reduced yields, and sometimes death.
Life Cycle
Whiteflies are closely related to scales, mealybugs, and aphids. They undergo complete metamorphosis with all life stages present at any time. Eggs are laid on the underside of the leaves. One female can lay about 200 to 400 eggs. They are usually laid in cigar- or circle-shaped clusters of 30 to 40 eggs. The eggs hatch in about a week into nymphs or crawlers. The crawlers wander about the plant and insert their mouth parts to feed on plant sap. When they molt, they lose their antennae and attach themselves to the underside of the leaves where they continue to feed until they pupate. Adults emerge and are about 1/10 to 1/16 inch long and look like a small white moth. The adult has four wings that are covered with a white, powdery, waxy substance. Within a population, all life stages are present, and generations often overlap. The life cycle takes only 18 days.
Integrated Pest Management Strategies
1. Inspection. Inspect all new plants brought indoors for whitefly. Inspect regularly, and remove by hand older leaves that are heavily infested with whiteflies in a non-mobile nymphal stage. Isolate new plants for a few days before placing them among other plants.
2. Mechanical control. The use of traps can be very helpful in controlling light infestations. Make yellow sticky traps about 12 x 6 inches and coat them with a sticky substance such as Tanglefoot, petroleum jelly, or heavy grade motor oil. Hang the traps vertically near the affected plants. The adults are attracted to yellow. Traps are also commercially available. One trap for every couple plants is recommended.
3. Chemical control. Whiteflies have developed resistance to some chemicals. Because of this resistance, a certain product may work well in one area but not in another. Resistance may be delayed by alternating the types of chemicals used. In addition, the egg and non-feeding pupa stages are generally not as susceptible to insecticides as are the adults and nymphs. Consequently, eradication of a whitefly population usually requires four to five applications of a registered insecticide at five to seven day intervals. Be sure the applications are made to the lower leaf surface, and apply as soon as whiteflies are detected. Do not wait until populations become severe.
Some of the over-the-counter chemicals that could be used contain permethrin or pyrethrins. Insecticidal soap, petroleum oil, and insect growth regulators can also be effective.
Before using any insecticide for whitefly control, make sure that the target plant is listed on the label and that the chemical is approved for use indoors. Follow label directions carefully.
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文章
Dummer. ゛☀
2017年09月17日
Scale insects are small, piercing-sucking insects that often go unnoticed on indoor plants. The adult forms can be attached to leaves, petioles, and stems. They suck plant juices and can cause plants to lose vigor.
Symptoms and Diagnosis
Since the insects are often overlooked, the first signs may be yellowing or wilting leaves that may eventually drop. Leaves may also be covered with a clear sticky substance called honeydew. Honeydew is the insects’ excrement consisting of partially digested sap and may coat the floor and other objects beneath the plant as it spatters down from above. A sticky floor beneath a susceptible plant is a telltale sign that infestation is underway. Under humid conditions, a black mold, called sooty mold, may grow on the honeydew making the leaves look dirty. Closer inspection will reveal small cottony or dome-shaped shells attached to stems and leaves. When pried off with a knifepoint, they may be hollow underneath or house adults and/or eggs. Scale can be differentiated from parts of the plant by scraping. If the structure is green when scraped or cannot be pried off, it is more than likely part of the plant.
Life Cycle
Scale insects have a simple life cycle of egg, nymph (crawler), and adult. Indoors, eggs can be laid any time under the protective shell. The eggs hatch and the crawlers seek out new feeding sites. This crawler stage is when scale is easiest to control. When the crawlers settle, they insert their mouth parts into the plant and begin feeding on the plant's sap. The protective shell develops soon after feeding begins and the insect loses use of its legs. Indoor scales can go through many generations a year.
Integrated Pest Management Strategies
1. Remove insects by hand. If caught early, scale insects can be rubbed off by hand, with a discarded toothbrush, or with a cotton swab soaked in isopropyl alcohol. Prune out heavily infested portions of the plant.
2. Use insecticidal soap. Monitor plants frequently. When crawlers are noticed, use insecticidal soaps that are formulated to kill insects and not damage plants. Frequent sprays may be needed until the problem is under control.
3. Use superior horticultural oil sprays. Highly refined oils sold as superior or ultra-refined horticultural oils are effective in controlling both adults and scale crawlers. The oil suffocates the insects. Unlike dormant oils, these oils are highly refined and under proper conditions, can be applied to plants in foliage without damage. Follow label directions to avoid damage to certain plants that may be sensitive. Superior oils are also considered nontoxic and are less likely to harm beneficial insects. When spraying indoors, protect surfaces that may be damaged by an oil residue.
4. Use chemical insecticides. Many insecticides registered for use indoors are available. Sprays containing pyrethrins, a plant-derived insecticide, are effective and more benign than other chemical pesticides. Follow label directions and, if possible, spray out-of-doors or in a garage, weather permitting.
5. To limit future problems, inspect plants regularly. With regular inspection, pest problems can be caught when just beginning and control is easier. It is also recommended to isolate newly acquired plants for 2–3 weeks to limit introducing pests indoors. Bringing plants indoors in the fall is another way of introducing insects indoors. Infested houseplants summered outdoors frequently benefit from the many natural enemies of scale. Be sure to check plants thoroughly before bringing them indoors in fall to be sure they are pest-free.
Symptoms and Diagnosis
Since the insects are often overlooked, the first signs may be yellowing or wilting leaves that may eventually drop. Leaves may also be covered with a clear sticky substance called honeydew. Honeydew is the insects’ excrement consisting of partially digested sap and may coat the floor and other objects beneath the plant as it spatters down from above. A sticky floor beneath a susceptible plant is a telltale sign that infestation is underway. Under humid conditions, a black mold, called sooty mold, may grow on the honeydew making the leaves look dirty. Closer inspection will reveal small cottony or dome-shaped shells attached to stems and leaves. When pried off with a knifepoint, they may be hollow underneath or house adults and/or eggs. Scale can be differentiated from parts of the plant by scraping. If the structure is green when scraped or cannot be pried off, it is more than likely part of the plant.
Life Cycle
Scale insects have a simple life cycle of egg, nymph (crawler), and adult. Indoors, eggs can be laid any time under the protective shell. The eggs hatch and the crawlers seek out new feeding sites. This crawler stage is when scale is easiest to control. When the crawlers settle, they insert their mouth parts into the plant and begin feeding on the plant's sap. The protective shell develops soon after feeding begins and the insect loses use of its legs. Indoor scales can go through many generations a year.
Integrated Pest Management Strategies
1. Remove insects by hand. If caught early, scale insects can be rubbed off by hand, with a discarded toothbrush, or with a cotton swab soaked in isopropyl alcohol. Prune out heavily infested portions of the plant.
2. Use insecticidal soap. Monitor plants frequently. When crawlers are noticed, use insecticidal soaps that are formulated to kill insects and not damage plants. Frequent sprays may be needed until the problem is under control.
3. Use superior horticultural oil sprays. Highly refined oils sold as superior or ultra-refined horticultural oils are effective in controlling both adults and scale crawlers. The oil suffocates the insects. Unlike dormant oils, these oils are highly refined and under proper conditions, can be applied to plants in foliage without damage. Follow label directions to avoid damage to certain plants that may be sensitive. Superior oils are also considered nontoxic and are less likely to harm beneficial insects. When spraying indoors, protect surfaces that may be damaged by an oil residue.
4. Use chemical insecticides. Many insecticides registered for use indoors are available. Sprays containing pyrethrins, a plant-derived insecticide, are effective and more benign than other chemical pesticides. Follow label directions and, if possible, spray out-of-doors or in a garage, weather permitting.
5. To limit future problems, inspect plants regularly. With regular inspection, pest problems can be caught when just beginning and control is easier. It is also recommended to isolate newly acquired plants for 2–3 weeks to limit introducing pests indoors. Bringing plants indoors in the fall is another way of introducing insects indoors. Infested houseplants summered outdoors frequently benefit from the many natural enemies of scale. Be sure to check plants thoroughly before bringing them indoors in fall to be sure they are pest-free.
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文章
Dummer. ゛☀
2017年09月17日
Oedema is a physiological disorder that develops when roots take up water faster than it can be used by the plant or transpired through the leaves. Water pressure builds up in the internal cells of the leaves causing them to burst, leaving dead cells that are visible as a blister, primarily on the undersides of leaves. Oedema may also be spelled edema.
Geraniums, rhododendrons, begonias, peperomias, jade plants, ficus, schefflera, and camellias are particularily sensitive to conditions that lead to the development of oedema, although almost any broadleaf plant may be affected.
Symptoms and Diagnosis
These blisters eventually erupt and form white, tan, or brown wart-like corky growths. As the condition worsens, leaves may turn yellow, droop, and fall off. In severely affected plants, blisters also form on the petioles and stems, although this is more rare. The upper surfaces of these leaves will often have indentations above the engorged cells on the undersides. If the problem is not corrected, the plants will become spindly.
On indoor plants, oedema is most prevalent in the late winter, especially during extended periods of cloudy weather. It is likely to develop when the soil is warm and the air is cool and moist. This environment results in rapid water absorption from the soil and slow water loss from the leaves. These conditions are most frequently encountered in greenhouses or indoor situations rather than outdoors but oedema can also be common on container-grown plants.
Integrated Pest Management Strategies
1. Culture. Oedema is a cultural problem so cut back on watering, but avoid letting plants dry out completely. If necessary, move the plant to a larger pot if it dries out too quickly.
2. Greenhouse conditions. When symptoms occur in a greenhouse, promote conditions that allow water loss to balance with water uptake by the roots. Decreasing humidity forces higher transpiration; ventilation is important as well as air temperature.
Geraniums, rhododendrons, begonias, peperomias, jade plants, ficus, schefflera, and camellias are particularily sensitive to conditions that lead to the development of oedema, although almost any broadleaf plant may be affected.
Symptoms and Diagnosis
These blisters eventually erupt and form white, tan, or brown wart-like corky growths. As the condition worsens, leaves may turn yellow, droop, and fall off. In severely affected plants, blisters also form on the petioles and stems, although this is more rare. The upper surfaces of these leaves will often have indentations above the engorged cells on the undersides. If the problem is not corrected, the plants will become spindly.
On indoor plants, oedema is most prevalent in the late winter, especially during extended periods of cloudy weather. It is likely to develop when the soil is warm and the air is cool and moist. This environment results in rapid water absorption from the soil and slow water loss from the leaves. These conditions are most frequently encountered in greenhouses or indoor situations rather than outdoors but oedema can also be common on container-grown plants.
Integrated Pest Management Strategies
1. Culture. Oedema is a cultural problem so cut back on watering, but avoid letting plants dry out completely. If necessary, move the plant to a larger pot if it dries out too quickly.
2. Greenhouse conditions. When symptoms occur in a greenhouse, promote conditions that allow water loss to balance with water uptake by the roots. Decreasing humidity forces higher transpiration; ventilation is important as well as air temperature.
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文章
Dummer. ゛☀
2017年09月17日
Many ornamental trees and shrubs are susceptible to Phytophthora root rot and can develop root and crown rot, particularly if the soil around the base of the plant remains wet for long periods of time. Typical symptoms of a root disease are apparent on infected plants. The leaves will appear droughtstressed and may die quickly as the weather warms in late spring or early summer. Trees that are especially susceptible include oak and dogwood.
Symptoms and Diagnosis
Leaves will appear drought stressed, sometimes turning dull green, yellow, red, or purple as they wilt. Infected trees may survive a few years before the disease kills the whole plant. The bark around the soil-line may appear darkened. Cutting away some bark should reveal red-brown discoloration in the wood underneath it. Disease symptoms are distinguishable from Armillaria root rot because mycelial mats do not develop in tissues infected with Phytophthora root rot.
Life Cycle
Root rot-causing Phytophthora species can survive in the soil for years, as long as moist conditions persist. It can spread through splashing rain, irrigation water, and runoff water. Disease fungi can spread through contaminated soil and garden equipment as well. Rot is more likely to spread in early spring and late fall during cool, rainy weather. But symptoms are more likely during stress periods of low rainfall. Flooded and saturated soil conditions for 6–8 hours are especially conducive to the spread of root rots. Wounds are not required for infection.
Integrated Pest Management Strategies
1. Improve water drainage. Prior to planting, make amendments to the soil composition to help manage drainage away from tree roots. Don’t allow water to pool around the collar or root system. Core aerate to improve drainage and lessen compaction.
2. Raise the planting site to avoid poor drainage and prevent pools of standing water from forming around valuable ornamentals. Plant on mounds of soil. Never plant trees deeper than they were planted at the nursery.
3. Separate plants, shrubs, and trees according to their irrigation needs, and avoid overwatering.
4. Remove soil. If soil has been piled up over the crown, remove it carefully to expose root flare. This is where fungal infection is likely to occur.
5. Plant resistant or less susceptible varieties. Consider replanting with tolerant plants after Phytophthora root rot has been diagnosed. Trees that are tolerant to Phytophthora root rot include white cedar and American arborvitae.
Symptoms and Diagnosis
Leaves will appear drought stressed, sometimes turning dull green, yellow, red, or purple as they wilt. Infected trees may survive a few years before the disease kills the whole plant. The bark around the soil-line may appear darkened. Cutting away some bark should reveal red-brown discoloration in the wood underneath it. Disease symptoms are distinguishable from Armillaria root rot because mycelial mats do not develop in tissues infected with Phytophthora root rot.
Life Cycle
Root rot-causing Phytophthora species can survive in the soil for years, as long as moist conditions persist. It can spread through splashing rain, irrigation water, and runoff water. Disease fungi can spread through contaminated soil and garden equipment as well. Rot is more likely to spread in early spring and late fall during cool, rainy weather. But symptoms are more likely during stress periods of low rainfall. Flooded and saturated soil conditions for 6–8 hours are especially conducive to the spread of root rots. Wounds are not required for infection.
Integrated Pest Management Strategies
1. Improve water drainage. Prior to planting, make amendments to the soil composition to help manage drainage away from tree roots. Don’t allow water to pool around the collar or root system. Core aerate to improve drainage and lessen compaction.
2. Raise the planting site to avoid poor drainage and prevent pools of standing water from forming around valuable ornamentals. Plant on mounds of soil. Never plant trees deeper than they were planted at the nursery.
3. Separate plants, shrubs, and trees according to their irrigation needs, and avoid overwatering.
4. Remove soil. If soil has been piled up over the crown, remove it carefully to expose root flare. This is where fungal infection is likely to occur.
5. Plant resistant or less susceptible varieties. Consider replanting with tolerant plants after Phytophthora root rot has been diagnosed. Trees that are tolerant to Phytophthora root rot include white cedar and American arborvitae.
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文章
Dummer. ゛☀
2017年09月17日
A weed is a plant that is not valued where it is growing and is usually of vigorous growth, especially one that tends to overgrow or choke out more desirable plants. Summer annual weeds emerge in the spring or early summer, grow during the summer, produce seed in mid to late summer, and are killed by frost in the fall. Following are some of the more common summer annual weeds for the St. Louis area. General control measures are listed at the end of this article.
GRASSES
Barnyardgrass
Barnyardgrass (Echinochloa crus-galli) is a summer annual grass that germinates from seeds from late winter or early spring throughout the summer. The stems are usually erect, thick, without hairs, often branched at the lower nodes, and may be tinted red to maroon at the base. The stems may reach 5 feet in height. The smooth, hairless leaves are rolled in the bud and contain neither ligules nor auricles. The dark green leaves, which range from 4 to 20 inches in length, have a distinct white midvein range. The seed head is green to reddish purple, with conspicuous, short stiff bristles or barbed spikelets. The roots are fibrous. Under close mowing, the broad, compressed purple sheaths of barnyardgrass lie flat on the ground and spread in a semicircular pattern. Barnyardgrass is found in moist soils, especially soils high in nutrients.
Crabgrass
Crabgrass, large and smooth (Digitaria sanguinalis, Digitaria ischaemum) are pale green summer annuals that has a prostrate or ascending growth habit. The two main species of crabgrass that occur in Missouri are smooth and large. Smooth crabgrass may be distinguished from large crabgrass by the absence of hairs on the leaves and sheath. Also smooth crabgrass does not root at the nodes like large crabgrass. Both species have a long, jagged membranous ligule and have no auricles. Crabgrass forms dense, unsightly patches that smother desirable turf grasses. Germination occurs when soil temperatures consistently reach 55 degrees F and is generally killed at the first frost. A crabgrass plant which needs warm soils and sunlight can produce 150,000 seeds. The seed head is composed of 2-6 branches (spikes) at the top of the stems forming 2 rows along the spike.
To control early in the season, use a pre-emergent herbicide as soon as soil temperatures reach 55 degrees F for a period of four days about the time forsythia blooms. A pre-emergent herbicide is recommended even if some crabgrass plants have germinated. There will still be crabgrass seed in the soil and the herbicide can prevent further infestation. Do not aerate after a pre-emergent herbicide application. For crabgrass control after germination, use a post-emergent selective grass herbicide.
Fall Panicum
Fall panicum (Panicum dichotomiflorum) is known as smooth witchgrass. It has a zigzag appearance as the buds turn out at the nodes. It has a very rounded stem, grows to 7’ and there is a purple tinge to its inflorescence. Sometimes it is confused with Johnson grass or barnyard grass, but fall panicum has a hairy ligule. Also its first true leaf has hairs on the underside of the blade, Johnson grass and barnyard grass do not.
Witchgrass
Panicum capillare is known as witchgrass or tickle grass. Culms are erect or spreading at the base. They are hollow, and pubescent at the nodes. They grow from 8 to 28” inches tall. The inflorescence is often ½ the length of the entire plant. It is purplish at maturity. It is softly hairy and the seeds are 1/16 of an inch. The head breaks off easily and rolls away in the wind, like a tumbleweed.
Goosegrass
Goosegrass (Elusine indica) is a prostrate-growing summer annual weed that grows in a clump. The leaves are distinctly folded in the bud and may be smooth or have a few sparse hairs at the base of the leaf. Goosegrass can be identified by the whitish stems at the base that are extremely compressed and flattened. The ligule is toothed and membranous with a cut in the center. There are no auricles. Goosegrass seed heads contain 3-7 spikes that form at the tip of the stalk. The seeds are attached in a zipper appearance on the spike. Goosegrass germinates about two weeks later than smooth crabgrass. Goosegrass can tolerate heavy traffic, dry compacted soils and low mowing heights.
Sandbur
Sandbur (Cenchrus longispinus) is a low-growing summer annual weed which is found in dense spreading patches most commonly in sandy soils. It roots at the nodes on the stems if they touch the ground. The leaves are folded in the bud, ¼ inch wide, and tapering to a point. The ligule is a short fringe of hairs and the auricles are absent. The seed head is a single spike with 6 to 20 rounded burs which contain 2 seeds in each bur. Sandbur seeds catch on clothing and animal fur and the barbed burs can easily pierce the skin and cause injury to livestock and people. Plants growing low to the ground can still produce burs. After a frost, entire plants become straw-colored, but stems with burs can persist through the winter. Seed dispersal occurs by animals, farm equipment, tires and in contaminated hay. Water is also important for seed dispersal, as burs float and may be carried for miles in irrigations ditches and other waterways.
Yellow Foxtail
Yellow foxtail (Setaria glauca) is a summer annual found especially in the Midwest and Eastern parts of the United States. It germinates when soil temperatures reach 65 degrees. Leaves are rolled in the bud. The ligule is a fringe of hairs. Auricles are absent. The collar is narrow and continuous. The blade contains hairs near the ligule. It has an upright growth pattern. The seed head is a bushy spike which resembles the tail of a fox.
BROADLEAFS
Black Medic
Black medic (Medicago lupulina) is a summer annual that can act as a perennial. The leaf is similar to other legumes, but the center leaflet is on a separate petiole. The flower is a compressed cluster of bright yellow flowers in the shape of a globular spike on short branches. The seed pod turns black at maturity. It will produce seeds at normal mowing heights. It can be confused with lespedeza (Kummerowia striata) unless it is blooming. Lespedeza has a bright blue flower.
Carpetweed
Carpetweed (Mollugo verticillata) is a summer annual with smooth prostrate branching stems forming circular mats. It is light green in color, the leaves are lanceolate in shape, widest in the middle and narrow at tip and base. Leaves form whorls containing 3-8 leaves. The flowers are white, have 5 petals, and form clusters of 2-5 flowers. Flowers are formed in the leaf axils. It spreads by seed, and is found throughout North America. Carpetweed germinates much later than other summer weeds. It grows quickly, especially in thin turf. Mowing misses it. It prefers rich moist soils, but it can establish itself in dry, sandy soil.
Lambsquarter
Lambsquarter (Chenopodium album) is an erect growing summer annual that may appear highly branched in a mowed setting. The immature leaves appear to be covered with a white mealy substance, especially on the underside of the leaf. The first pair of leaves are opposite, and subsequent leaves are alternate along the stems. Leaf margins vary, but usually are irregularly lobed. The root of lambsquarter is a short, branched taproot. The flowers are found in small green clusters and lack petals. The clusters of flowers form in terminal spikes. Lambsquarter spreads by black seeds that germinate in the late spring to early summer. Each plant produces thousands of tiny seeds that may remain viable for years. When lambsquarter is abundant, it is reported to cause hay fever symptoms.
Mallow
Mallow (Hibiscus trionum) is a summer annual-- it is also called “flower of an hour”. There is a winter annual mallow, it is usually called the common mallow. H. trionum is grown in Europe as an ornamental. It is upright 10-18”. It is covered with hairs. The leaves are deeply cleft with 3-5 coarsely toothed lobes on long petioles. The lower stems and petioles are red to purple in color. It has a fibrous root system with a weak taproot. It has a showy flower. It is light sulfur-yellow in color with a deep red to purple center. It does last 2-3 hours then the petals drop. It spreads by seed. The seed can be dormant for 50 years. It is found throughout the U.S. Mallow can infest nurseries, orchards, roadsides, cultivated fields and open areas. It tolerates drought, alkaline soil, and gravelly soils.
Pigweed
Pigweed is actually toxic to pigs and cows. This summer annual has alternate leaves. There are 10 pigweeds (Amaranthus) identified through the corn belt area: redroot, smooth, rough pigweed, Powell, tumble, prostrate, spiny, tall, sandhill and another one. The difference is in the flower. The leaves are alternate, the seeds (1/25”) are shiny, round and flat. The plant can reach 2-4’ for the smaller ones and up to 61/2’ for the larger ones.
Prostrate knotweed
Prostrate knotweed (Polygonum aviculare) is a summer annual which resembles a grass with long, dark leaves as the seedling emerges. Later, it forms a flat mat up to 2 to 3 feet in diameter on slender wiry stems that emerge from a tap root. There are papery sheath or ocrea at each node that give the stems a knotted or swollen appearance. The alternate leaves are small and narrowly oval, dull and bluish green, and 1 ¼ inches long by 1/3 inch wide. The flowers are small pink to white and form in clusters in the leaf axis. Knotweed is found in compacted, infertile soil or thin turf in the sun. Smartweed is a close relative of knotweed, but it has a purple ocrea encircling the stem. Spotted spurge may be confused with knotweed, but the spurges do not have an ocrea and emit a milky sap when cut, unlike prostrate knotweed.
Puncturevine
Puncturevine (Tribulus terrestris) is a summer annual weed with multiple stems prostrate along the ground. Stems may be up to five feet long originating from a taproot. Leaves are compound pinnate with four to eight pairs of hairy leaflets. Each leaflet is less than ½ inch long. The small yellow flowers have five petals and are about 1/3 inch wide. The flowers, which consist of 5 petals, produce hard, spiny, five-lobed fruit. Bloom is in late spring and early summer. At maturity the fruit breaks into tack-like structures each containing 2 to 4 seeds. Seed nutlets disperse by adhering to tires, shoes and clothing of people, fur, feathers, and feet of animals. These burs can injure people and animals and can damage bike and car tires. Foliage is toxic to livestock, especially sheep, when consumed in quantity. The fruit is used medicinally in India.
Purslane
Purslane (Portulaca oleracea) is a prostrate mat-forming summer annual that can reach up to 24 inches long. It has multi-branched red stems that root at the nodes wherever they contact the soil surface. The smooth, thick, fleshy leaves are usually alternate and are often clustered near the ends of the branches. The entire plant is very succulent and resembles a jade plant. Purslane is common to disturbed soil, new seedlings, sidewalk crevices and mulched planting beds. It prefers high light and warm conditions. This plant reproduces by seeds that are formed in a capsule with a lid that flips open in the spring. Solitary yellow flowers with 5 petals will only open with sunny conditions from May to September. Purslane’s use as a medicinal herb to treat dysentery, headache, and stomach ache dates back 2000 years. It was also used as a salad green by the Australian aborigines, by the Chinese, French, Italians, and the English.
Ragweed
Ragweed (Ambrosia artemisifolia) is a summer annual that produces pollen. One weed equals 1 billion grains of pollen, 100 million tons of pollen are produced per year. It grows up to 5’ tall. Opposite leaves are egg-shaped in outline and once or twice compound (pinnatified), they are hairy on their upper surface and margin. Leaves can be up to 6” long, The erect stems have long rough hairs. The fruit is an achene, which resembles a queen’s crown. It has a shallow taproot. There is a giant ragweed (Ambrosia tridida) which grows up to 14’ high. No animal eats ragweed.
Spurge
Prostrate spurge (Euphorbia supine) and spotted spurge (Euphorbia maculate) are summer annual weeds. Spotted spurge has a more erect growth habit than prostrate spurge. Prostrate spurge forms dense mats with its stems radiating out from a shallow taproot. Both species have similar leaves, which are small and oblong with an irregular maroon to purple spot in their center. However, the leaves of spotted spurge are slightly larger than those of prostrate spurge. Both spurges have leaves that grow opposite on the stem, but spotted spurge has fewer leaves per stem. When the leaves of both spurges are broken or injured they emit a milky white sap (similar to dandelion). Prostrate spurge roots at the nodes, but spotted spurge does not. Both spurges reproduce from seed. The flower of spotted spurge is small and green in color. Prostrate spurge has inconspicuous small, pinkish white flowers in the leaf axils.
Vervain
Vervain (Verbena officinalis) is known as the herb of enchantment. It is used medically in 30 complaints. Supposedly vervain staunched the wounds of Christ on the Mount of Calvary. It has a slightly bitter taste and it has no scent. Vervain is rarely perennial, the leaves are numerous, opposite, lanceolate to ovate ½ to 3” long. It is pinnately toothed, it can have 3 lobes, with the center lobe larger than the others. The leaves are hairy on both surfaces. The flower is a dense terminal spike 1-8” long, usually ascending. The flower is blue or purple with 5 lobes, the tiny flowers are almost hidden by conspicuous hairy bracts.
Integrated Pest Management Strategies for Summer Annual Weeds
1. Use good cultural practices to prevent the spread of summer annual weeds. Maintain a dense actively growing turf through proper mowing, fertilizing and watering practices. Most lawns should be cut at least 2 inches or higher. Watering deeply (4-6 inches) just before the turf begins to wilt is a sound approach. Frequent light watering promotes weak turf with shallow roots which are more susceptible to insect and disease attacks as well as weed invasion. Complete soil testing is the key to proper liming and fertilization. Cultural practices for the control of summer annual weeds are aimed at shading and crowding the young weed seedlings by producing a dense sod.
2. Dig up the weeds.
3. Coring and traffic control reduce compaction and encourage desirable turfgrass growth. Mulch flower beds to control weeds.
4. Use chemical herbicides. Use a post-emergent herbicide when the weed is young, usually three to four leaf stage. It is best to control summer annual weeds in late spring or early summer when they are young. They are easier to control at that time and both warm season and cool season turfgrasses have a greater chance to recover the areas previously occupied by weeds. There are also some pre-emergent herbicides available which form a chemical barrier in the soil and prevent the weeds from emerging. Check herbicide labels to verify that the herbicide you have chosen is effective in controlling your problem weed and when and how to apply.
GRASSES
Barnyardgrass
Barnyardgrass (Echinochloa crus-galli) is a summer annual grass that germinates from seeds from late winter or early spring throughout the summer. The stems are usually erect, thick, without hairs, often branched at the lower nodes, and may be tinted red to maroon at the base. The stems may reach 5 feet in height. The smooth, hairless leaves are rolled in the bud and contain neither ligules nor auricles. The dark green leaves, which range from 4 to 20 inches in length, have a distinct white midvein range. The seed head is green to reddish purple, with conspicuous, short stiff bristles or barbed spikelets. The roots are fibrous. Under close mowing, the broad, compressed purple sheaths of barnyardgrass lie flat on the ground and spread in a semicircular pattern. Barnyardgrass is found in moist soils, especially soils high in nutrients.
Crabgrass
Crabgrass, large and smooth (Digitaria sanguinalis, Digitaria ischaemum) are pale green summer annuals that has a prostrate or ascending growth habit. The two main species of crabgrass that occur in Missouri are smooth and large. Smooth crabgrass may be distinguished from large crabgrass by the absence of hairs on the leaves and sheath. Also smooth crabgrass does not root at the nodes like large crabgrass. Both species have a long, jagged membranous ligule and have no auricles. Crabgrass forms dense, unsightly patches that smother desirable turf grasses. Germination occurs when soil temperatures consistently reach 55 degrees F and is generally killed at the first frost. A crabgrass plant which needs warm soils and sunlight can produce 150,000 seeds. The seed head is composed of 2-6 branches (spikes) at the top of the stems forming 2 rows along the spike.
To control early in the season, use a pre-emergent herbicide as soon as soil temperatures reach 55 degrees F for a period of four days about the time forsythia blooms. A pre-emergent herbicide is recommended even if some crabgrass plants have germinated. There will still be crabgrass seed in the soil and the herbicide can prevent further infestation. Do not aerate after a pre-emergent herbicide application. For crabgrass control after germination, use a post-emergent selective grass herbicide.
Fall Panicum
Fall panicum (Panicum dichotomiflorum) is known as smooth witchgrass. It has a zigzag appearance as the buds turn out at the nodes. It has a very rounded stem, grows to 7’ and there is a purple tinge to its inflorescence. Sometimes it is confused with Johnson grass or barnyard grass, but fall panicum has a hairy ligule. Also its first true leaf has hairs on the underside of the blade, Johnson grass and barnyard grass do not.
Witchgrass
Panicum capillare is known as witchgrass or tickle grass. Culms are erect or spreading at the base. They are hollow, and pubescent at the nodes. They grow from 8 to 28” inches tall. The inflorescence is often ½ the length of the entire plant. It is purplish at maturity. It is softly hairy and the seeds are 1/16 of an inch. The head breaks off easily and rolls away in the wind, like a tumbleweed.
Goosegrass
Goosegrass (Elusine indica) is a prostrate-growing summer annual weed that grows in a clump. The leaves are distinctly folded in the bud and may be smooth or have a few sparse hairs at the base of the leaf. Goosegrass can be identified by the whitish stems at the base that are extremely compressed and flattened. The ligule is toothed and membranous with a cut in the center. There are no auricles. Goosegrass seed heads contain 3-7 spikes that form at the tip of the stalk. The seeds are attached in a zipper appearance on the spike. Goosegrass germinates about two weeks later than smooth crabgrass. Goosegrass can tolerate heavy traffic, dry compacted soils and low mowing heights.
Sandbur
Sandbur (Cenchrus longispinus) is a low-growing summer annual weed which is found in dense spreading patches most commonly in sandy soils. It roots at the nodes on the stems if they touch the ground. The leaves are folded in the bud, ¼ inch wide, and tapering to a point. The ligule is a short fringe of hairs and the auricles are absent. The seed head is a single spike with 6 to 20 rounded burs which contain 2 seeds in each bur. Sandbur seeds catch on clothing and animal fur and the barbed burs can easily pierce the skin and cause injury to livestock and people. Plants growing low to the ground can still produce burs. After a frost, entire plants become straw-colored, but stems with burs can persist through the winter. Seed dispersal occurs by animals, farm equipment, tires and in contaminated hay. Water is also important for seed dispersal, as burs float and may be carried for miles in irrigations ditches and other waterways.
Yellow Foxtail
Yellow foxtail (Setaria glauca) is a summer annual found especially in the Midwest and Eastern parts of the United States. It germinates when soil temperatures reach 65 degrees. Leaves are rolled in the bud. The ligule is a fringe of hairs. Auricles are absent. The collar is narrow and continuous. The blade contains hairs near the ligule. It has an upright growth pattern. The seed head is a bushy spike which resembles the tail of a fox.
BROADLEAFS
Black Medic
Black medic (Medicago lupulina) is a summer annual that can act as a perennial. The leaf is similar to other legumes, but the center leaflet is on a separate petiole. The flower is a compressed cluster of bright yellow flowers in the shape of a globular spike on short branches. The seed pod turns black at maturity. It will produce seeds at normal mowing heights. It can be confused with lespedeza (Kummerowia striata) unless it is blooming. Lespedeza has a bright blue flower.
Carpetweed
Carpetweed (Mollugo verticillata) is a summer annual with smooth prostrate branching stems forming circular mats. It is light green in color, the leaves are lanceolate in shape, widest in the middle and narrow at tip and base. Leaves form whorls containing 3-8 leaves. The flowers are white, have 5 petals, and form clusters of 2-5 flowers. Flowers are formed in the leaf axils. It spreads by seed, and is found throughout North America. Carpetweed germinates much later than other summer weeds. It grows quickly, especially in thin turf. Mowing misses it. It prefers rich moist soils, but it can establish itself in dry, sandy soil.
Lambsquarter
Lambsquarter (Chenopodium album) is an erect growing summer annual that may appear highly branched in a mowed setting. The immature leaves appear to be covered with a white mealy substance, especially on the underside of the leaf. The first pair of leaves are opposite, and subsequent leaves are alternate along the stems. Leaf margins vary, but usually are irregularly lobed. The root of lambsquarter is a short, branched taproot. The flowers are found in small green clusters and lack petals. The clusters of flowers form in terminal spikes. Lambsquarter spreads by black seeds that germinate in the late spring to early summer. Each plant produces thousands of tiny seeds that may remain viable for years. When lambsquarter is abundant, it is reported to cause hay fever symptoms.
Mallow
Mallow (Hibiscus trionum) is a summer annual-- it is also called “flower of an hour”. There is a winter annual mallow, it is usually called the common mallow. H. trionum is grown in Europe as an ornamental. It is upright 10-18”. It is covered with hairs. The leaves are deeply cleft with 3-5 coarsely toothed lobes on long petioles. The lower stems and petioles are red to purple in color. It has a fibrous root system with a weak taproot. It has a showy flower. It is light sulfur-yellow in color with a deep red to purple center. It does last 2-3 hours then the petals drop. It spreads by seed. The seed can be dormant for 50 years. It is found throughout the U.S. Mallow can infest nurseries, orchards, roadsides, cultivated fields and open areas. It tolerates drought, alkaline soil, and gravelly soils.
Pigweed
Pigweed is actually toxic to pigs and cows. This summer annual has alternate leaves. There are 10 pigweeds (Amaranthus) identified through the corn belt area: redroot, smooth, rough pigweed, Powell, tumble, prostrate, spiny, tall, sandhill and another one. The difference is in the flower. The leaves are alternate, the seeds (1/25”) are shiny, round and flat. The plant can reach 2-4’ for the smaller ones and up to 61/2’ for the larger ones.
Prostrate knotweed
Prostrate knotweed (Polygonum aviculare) is a summer annual which resembles a grass with long, dark leaves as the seedling emerges. Later, it forms a flat mat up to 2 to 3 feet in diameter on slender wiry stems that emerge from a tap root. There are papery sheath or ocrea at each node that give the stems a knotted or swollen appearance. The alternate leaves are small and narrowly oval, dull and bluish green, and 1 ¼ inches long by 1/3 inch wide. The flowers are small pink to white and form in clusters in the leaf axis. Knotweed is found in compacted, infertile soil or thin turf in the sun. Smartweed is a close relative of knotweed, but it has a purple ocrea encircling the stem. Spotted spurge may be confused with knotweed, but the spurges do not have an ocrea and emit a milky sap when cut, unlike prostrate knotweed.
Puncturevine
Puncturevine (Tribulus terrestris) is a summer annual weed with multiple stems prostrate along the ground. Stems may be up to five feet long originating from a taproot. Leaves are compound pinnate with four to eight pairs of hairy leaflets. Each leaflet is less than ½ inch long. The small yellow flowers have five petals and are about 1/3 inch wide. The flowers, which consist of 5 petals, produce hard, spiny, five-lobed fruit. Bloom is in late spring and early summer. At maturity the fruit breaks into tack-like structures each containing 2 to 4 seeds. Seed nutlets disperse by adhering to tires, shoes and clothing of people, fur, feathers, and feet of animals. These burs can injure people and animals and can damage bike and car tires. Foliage is toxic to livestock, especially sheep, when consumed in quantity. The fruit is used medicinally in India.
Purslane
Purslane (Portulaca oleracea) is a prostrate mat-forming summer annual that can reach up to 24 inches long. It has multi-branched red stems that root at the nodes wherever they contact the soil surface. The smooth, thick, fleshy leaves are usually alternate and are often clustered near the ends of the branches. The entire plant is very succulent and resembles a jade plant. Purslane is common to disturbed soil, new seedlings, sidewalk crevices and mulched planting beds. It prefers high light and warm conditions. This plant reproduces by seeds that are formed in a capsule with a lid that flips open in the spring. Solitary yellow flowers with 5 petals will only open with sunny conditions from May to September. Purslane’s use as a medicinal herb to treat dysentery, headache, and stomach ache dates back 2000 years. It was also used as a salad green by the Australian aborigines, by the Chinese, French, Italians, and the English.
Ragweed
Ragweed (Ambrosia artemisifolia) is a summer annual that produces pollen. One weed equals 1 billion grains of pollen, 100 million tons of pollen are produced per year. It grows up to 5’ tall. Opposite leaves are egg-shaped in outline and once or twice compound (pinnatified), they are hairy on their upper surface and margin. Leaves can be up to 6” long, The erect stems have long rough hairs. The fruit is an achene, which resembles a queen’s crown. It has a shallow taproot. There is a giant ragweed (Ambrosia tridida) which grows up to 14’ high. No animal eats ragweed.
Spurge
Prostrate spurge (Euphorbia supine) and spotted spurge (Euphorbia maculate) are summer annual weeds. Spotted spurge has a more erect growth habit than prostrate spurge. Prostrate spurge forms dense mats with its stems radiating out from a shallow taproot. Both species have similar leaves, which are small and oblong with an irregular maroon to purple spot in their center. However, the leaves of spotted spurge are slightly larger than those of prostrate spurge. Both spurges have leaves that grow opposite on the stem, but spotted spurge has fewer leaves per stem. When the leaves of both spurges are broken or injured they emit a milky white sap (similar to dandelion). Prostrate spurge roots at the nodes, but spotted spurge does not. Both spurges reproduce from seed. The flower of spotted spurge is small and green in color. Prostrate spurge has inconspicuous small, pinkish white flowers in the leaf axils.
Vervain
Vervain (Verbena officinalis) is known as the herb of enchantment. It is used medically in 30 complaints. Supposedly vervain staunched the wounds of Christ on the Mount of Calvary. It has a slightly bitter taste and it has no scent. Vervain is rarely perennial, the leaves are numerous, opposite, lanceolate to ovate ½ to 3” long. It is pinnately toothed, it can have 3 lobes, with the center lobe larger than the others. The leaves are hairy on both surfaces. The flower is a dense terminal spike 1-8” long, usually ascending. The flower is blue or purple with 5 lobes, the tiny flowers are almost hidden by conspicuous hairy bracts.
Integrated Pest Management Strategies for Summer Annual Weeds
1. Use good cultural practices to prevent the spread of summer annual weeds. Maintain a dense actively growing turf through proper mowing, fertilizing and watering practices. Most lawns should be cut at least 2 inches or higher. Watering deeply (4-6 inches) just before the turf begins to wilt is a sound approach. Frequent light watering promotes weak turf with shallow roots which are more susceptible to insect and disease attacks as well as weed invasion. Complete soil testing is the key to proper liming and fertilization. Cultural practices for the control of summer annual weeds are aimed at shading and crowding the young weed seedlings by producing a dense sod.
2. Dig up the weeds.
3. Coring and traffic control reduce compaction and encourage desirable turfgrass growth. Mulch flower beds to control weeds.
4. Use chemical herbicides. Use a post-emergent herbicide when the weed is young, usually three to four leaf stage. It is best to control summer annual weeds in late spring or early summer when they are young. They are easier to control at that time and both warm season and cool season turfgrasses have a greater chance to recover the areas previously occupied by weeds. There are also some pre-emergent herbicides available which form a chemical barrier in the soil and prevent the weeds from emerging. Check herbicide labels to verify that the herbicide you have chosen is effective in controlling your problem weed and when and how to apply.
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0
文章
Dummer. ゛☀
2017年09月17日
Two of the most damaging insects on perennial plants are the tarnished plant bug, Lygus lineolaris, and the four-lined plant bug, Poecilocapsus lineatus. These two plant bugs can cause serious problems because they have such a wide variety of host plants. The four-lined plant bug feeds on 250 plant species which are mostly herbaceous. The tarnished plant bug is a problem on a wide variety of ornamental flowers.
Symptoms and Diagnosis
Damage varies slightly from the two plant bugs. The four-lined plant bugs cause small (1/16 inch), discolored areas on leaves where they suck out cell juices. Injured areas will turn black or become translucent, and after several weeks, the dead tissue may drop out, leaving small holes. The adults feed on the upper surfaces of leaves and are voracious feeders. The topmost leaves will generally be the first to be injured.
Damage from the tarnished plant bug is in the form of distorted foliage or disbudded plants. This damage is caused by the overwintered adults which attack swollen and opening buds in the early spring. The disbudding will cause the plant to be short and bushy. If the attack takes place after shoot elongation begins, the tip will often turn black and die, or it will be so damaged that shoot stunting or distortion occurs. Stems frequently break at the injured area.
Life Cycle
The four-lined plant bug overwinters as eggs inserted into a slit near the top of tender shoots. Nymphs emerge from the eggs in May. Nymphal coloring varies from bright red to yellow. The species requires about 30 days to complete nymphal development. Forewings of adults are yellow, but may turn bright green. However, the four black stripes that give the insect its name remain distinct. This species normally has one generation a year.
Adults of the tarnished plant bug overwinter as adults in leaf litter. Beginning in the spring, they lay eggs mainly in the stems and flowers of herbaceous plants. After hatching, the young nymphs usually remain to feed on the same plant until they mature. The nymph is green or pale yellow and grows rapidly. Adults are capable flyers and readily move from place to place. There may be two to five generations per year. In midsummer, a life cycle may be completed in about 25 days. By late summer, populations can become very abundant.
Integrated Pest Management Strategies
1. Live with the damage. Since damage is often cosmetic, some damage can be tolerated. Often, natural predators will keep the insects under control.
2. Remove leaf litter. To limit problems in coming years, clean up leaf litter to avoid overwintering sites for tarnished plant bugs.
3. Prune out egg masses. Learn to identify the egg masses of four-lined plant bugs and prune them out in winter.
4. Use insecticidal soaps. If populations are high enough, spraying with an insecticidal soap may be necessary. Because the tarnished plant bug can go through many generations in a single year and cause great damage to a plant, it is best to initiate control when it first appears.
5. If necessary, use chemical insecticides. Plant bugs can be controlled with malathion, and carbaryl (Sevin).
Symptoms and Diagnosis
Damage varies slightly from the two plant bugs. The four-lined plant bugs cause small (1/16 inch), discolored areas on leaves where they suck out cell juices. Injured areas will turn black or become translucent, and after several weeks, the dead tissue may drop out, leaving small holes. The adults feed on the upper surfaces of leaves and are voracious feeders. The topmost leaves will generally be the first to be injured.
Damage from the tarnished plant bug is in the form of distorted foliage or disbudded plants. This damage is caused by the overwintered adults which attack swollen and opening buds in the early spring. The disbudding will cause the plant to be short and bushy. If the attack takes place after shoot elongation begins, the tip will often turn black and die, or it will be so damaged that shoot stunting or distortion occurs. Stems frequently break at the injured area.
Life Cycle
The four-lined plant bug overwinters as eggs inserted into a slit near the top of tender shoots. Nymphs emerge from the eggs in May. Nymphal coloring varies from bright red to yellow. The species requires about 30 days to complete nymphal development. Forewings of adults are yellow, but may turn bright green. However, the four black stripes that give the insect its name remain distinct. This species normally has one generation a year.
Adults of the tarnished plant bug overwinter as adults in leaf litter. Beginning in the spring, they lay eggs mainly in the stems and flowers of herbaceous plants. After hatching, the young nymphs usually remain to feed on the same plant until they mature. The nymph is green or pale yellow and grows rapidly. Adults are capable flyers and readily move from place to place. There may be two to five generations per year. In midsummer, a life cycle may be completed in about 25 days. By late summer, populations can become very abundant.
Integrated Pest Management Strategies
1. Live with the damage. Since damage is often cosmetic, some damage can be tolerated. Often, natural predators will keep the insects under control.
2. Remove leaf litter. To limit problems in coming years, clean up leaf litter to avoid overwintering sites for tarnished plant bugs.
3. Prune out egg masses. Learn to identify the egg masses of four-lined plant bugs and prune them out in winter.
4. Use insecticidal soaps. If populations are high enough, spraying with an insecticidal soap may be necessary. Because the tarnished plant bug can go through many generations in a single year and cause great damage to a plant, it is best to initiate control when it first appears.
5. If necessary, use chemical insecticides. Plant bugs can be controlled with malathion, and carbaryl (Sevin).
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文章
Dummer. ゛☀
2017年09月17日
The phlox plant bug, Lopidea davisi, is an eye catching true bug. It is reddish orange and black. It is a piercing sucking insect with a long proboscis. It feeds mainly on phlox and can cause serious damage to phlox.
Symptoms and Diagnosis
The phlox bug’s feeding causes white or light green spots on the leaves and buds that later show yellow stippling. The leaves then turn brown, curl, dry out and drop. The plant may become stunted and die. The bug feeds on leaves, stem terminals, flowers and seeds. It may be hard to see because it hides on the underside of leaves.
Life Cycle
The phlox bug overwinters in the egg stage in dead phlox stems. It has two generations per year. The first generation appears in late spring, the second in mid to late summer. It undergoes incomplete metamorphosis.
Integrated Pest Management Strategies
1. Practice good sanitation. Cut back and dispose of badly infested stems and leaves. Clean up stem and leaf litter of phlox and neighboring plants in winter before early spring.
2. Scout for nymphs and treat. Apply insecticidal soap to both the upper and underside of the leaves. Use a light horticultural oil.
3. Use chemical controls if warranted. Products listed for use include pyrethrins, permethrin or acephate (orthene), a systemic.
Symptoms and Diagnosis
The phlox bug’s feeding causes white or light green spots on the leaves and buds that later show yellow stippling. The leaves then turn brown, curl, dry out and drop. The plant may become stunted and die. The bug feeds on leaves, stem terminals, flowers and seeds. It may be hard to see because it hides on the underside of leaves.
Life Cycle
The phlox bug overwinters in the egg stage in dead phlox stems. It has two generations per year. The first generation appears in late spring, the second in mid to late summer. It undergoes incomplete metamorphosis.
Integrated Pest Management Strategies
1. Practice good sanitation. Cut back and dispose of badly infested stems and leaves. Clean up stem and leaf litter of phlox and neighboring plants in winter before early spring.
2. Scout for nymphs and treat. Apply insecticidal soap to both the upper and underside of the leaves. Use a light horticultural oil.
3. Use chemical controls if warranted. Products listed for use include pyrethrins, permethrin or acephate (orthene), a systemic.
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文章
Dummer. ゛☀
2017年09月16日
Numerous species of leafhoppers and planthoppers are found in Missouri, and many of them have a broad host list (for example, the potato leafhopper, Empoasca fabae, has over 100 host plants). They feed on foliage and shoots of many different plant species by piercing the plant cells and sucking out the contents. The damage that results from feeding depends on the host plant and the specific hopper. Only a few species of hoppers transmit pathogens such as those that cause curly top virus and aster yellows. Adult hoppers are excellent short-distance jumpers when disturbed, and they can be pests when found in high numbers.
Symptoms and Diagnosis
Hoppers are agile insects that can move with equal ease either forwards, backwards, or sideways like a crab. The crab-like motion distinguishes hoppers from most other insects. In addition, they can hop to escape danger or to move to another host plant.
Feeding damage from some species causes small white spots (stippling) to appear on the upper leaf surface, usually beginning near the leaf midrib.
Stippled areas can unite into larger whitish blotches on mature leaves. With some plants, feeding damage causes a drying and yellowing (or browning) of leaf margins, and possibly the whole leaf. Some leafhopper species cause curling or stunting of terminal leaves with their feeding. Another sign of feeding is the presence of tiny varnish-like spots of excrement on the underside of leaves. Also, check under leaves for white, papery cast skins that remain from the molting process.
The lacebug is another insect that causes stippling from feeding and leaves dark droplets of varnish-like excrement on the underside of leaves. Distinguishing lacebugs from leafhoppers is easy:
Lacebugs have a lacy pattern on their upper side, they don't jump or run sideways, and they are about half as broad as they are long. Yet another pest that can cause stippling is the spider mite. Check under leaves for the webbing left by spider mites (leafhoppers don't leave webbing).
Life Cycle
Adults of most species of leafhopper range between 1/8 to 1/4 inch long. They are slender and frequently have an angular, pointed head. Coloration depends on species, but generally leafhoppers are shades of green, brown, or yellow and are often mottled. Nymphs (immatures) look similar to the adults except that the nymphs are smaller and don't have wings. Nymphs typically feed on the underside of leaves, where the humidity is higher and they are more protected from predators.
Leafhoppers have several generations each year. Some species migrate south in winter and return north with late spring weather.
Integrated Pest Management Strategies
1. Live with the pests. Because of their mobility and abundance, leafhoppers are not easy to control. However, leafhoppers are seldom present in large enough numbers to seriously injure plants. In addition, leafhoppers have many natural enemies, including lady beetles, lacewings, damsel bugs, and spiders. They are also subject to diseases and parasites that help keep their numbers down under most conditions.
2. Use row covers. Floating row covers or netting can be placed over plants early in summer to exclude leafhoppers. Remove row covers when the plants begin to flower.
3. Monitor with sticky traps. Many leafhoppers are attracted to yellow sticky traps which should be placed close to the foliage of the crop. Populations can be monitored with sticky traps and low populations can be managed using these traps.
4. Apply insecticidal soap. Insecticidal soap can control leafhoppers if applied when the insects are small. The immature leafhoppers are usually found on the underside of leaves so be sure to spray there also.
5. Apply insecticides. Other insecticides available for leafhopper control include botanical pyrethrins, carbaryl (Sevin), malathion, bifenthrin, cyfluthrin, bendiocarb (Turcam, Closure), disulfoton (Disyston), and acephate (Orthene). In general, these are most effective on the immature leafhoppers because they can't escape as well as the adults and are typically more susceptible to chemicals.
Symptoms and Diagnosis
Hoppers are agile insects that can move with equal ease either forwards, backwards, or sideways like a crab. The crab-like motion distinguishes hoppers from most other insects. In addition, they can hop to escape danger or to move to another host plant.
Feeding damage from some species causes small white spots (stippling) to appear on the upper leaf surface, usually beginning near the leaf midrib.
Stippled areas can unite into larger whitish blotches on mature leaves. With some plants, feeding damage causes a drying and yellowing (or browning) of leaf margins, and possibly the whole leaf. Some leafhopper species cause curling or stunting of terminal leaves with their feeding. Another sign of feeding is the presence of tiny varnish-like spots of excrement on the underside of leaves. Also, check under leaves for white, papery cast skins that remain from the molting process.
The lacebug is another insect that causes stippling from feeding and leaves dark droplets of varnish-like excrement on the underside of leaves. Distinguishing lacebugs from leafhoppers is easy:
Lacebugs have a lacy pattern on their upper side, they don't jump or run sideways, and they are about half as broad as they are long. Yet another pest that can cause stippling is the spider mite. Check under leaves for the webbing left by spider mites (leafhoppers don't leave webbing).
Life Cycle
Adults of most species of leafhopper range between 1/8 to 1/4 inch long. They are slender and frequently have an angular, pointed head. Coloration depends on species, but generally leafhoppers are shades of green, brown, or yellow and are often mottled. Nymphs (immatures) look similar to the adults except that the nymphs are smaller and don't have wings. Nymphs typically feed on the underside of leaves, where the humidity is higher and they are more protected from predators.
Leafhoppers have several generations each year. Some species migrate south in winter and return north with late spring weather.
Integrated Pest Management Strategies
1. Live with the pests. Because of their mobility and abundance, leafhoppers are not easy to control. However, leafhoppers are seldom present in large enough numbers to seriously injure plants. In addition, leafhoppers have many natural enemies, including lady beetles, lacewings, damsel bugs, and spiders. They are also subject to diseases and parasites that help keep their numbers down under most conditions.
2. Use row covers. Floating row covers or netting can be placed over plants early in summer to exclude leafhoppers. Remove row covers when the plants begin to flower.
3. Monitor with sticky traps. Many leafhoppers are attracted to yellow sticky traps which should be placed close to the foliage of the crop. Populations can be monitored with sticky traps and low populations can be managed using these traps.
4. Apply insecticidal soap. Insecticidal soap can control leafhoppers if applied when the insects are small. The immature leafhoppers are usually found on the underside of leaves so be sure to spray there also.
5. Apply insecticides. Other insecticides available for leafhopper control include botanical pyrethrins, carbaryl (Sevin), malathion, bifenthrin, cyfluthrin, bendiocarb (Turcam, Closure), disulfoton (Disyston), and acephate (Orthene). In general, these are most effective on the immature leafhoppers because they can't escape as well as the adults and are typically more susceptible to chemicals.
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