文章
Dummer. ゛☀
2017年09月18日
Procera root rot also known as white pine root decline is caused by the fungus Leptographium procerum (syn. Verticicladiella procera). It infects the inner bark and sapwood of the roots and lower trunk of white pine. Although the disease is most serious on white pine, it can also kill Scots and Austrian pines.
Symptoms and Diagnosis
In the Spring, trees, aged 3 to 15 years, which have been infected for several years, show delayed bud break and reduced candle elongation. Mature foliage then fades, droops, and turns brown, in stark contrast to healthy trees nearby. Mortality appears to be at random with a few trees dying each year. Resin flow is visible at the tree base and is associated with a girdling chocolate brown to dark olive-brown canker under the bark. The trunk may be flattened on the affected side. Galleries of insects such as the pine root collar weevil may be found in the canker and provide a place for the fungus to sporulate. Weevils and other bark-infesting insects may serve as vectors for this disease. Although the fungus does not survive well in the soil, it may be spread by contaminated insects as they emerge from diseased trees and feed on healthy trees nearby.
Integrated Pest Management Strategies
1. Planting. Avoid planting eastern white pine on wet sites. Trees planted on wet sites seem to be more susceptible to the fungus. Excessively dry sites also seem to predispose trees to attack.
2. Sanitation. Remove and destroy infected trees including stumps, if possible. Do not replant eastern white pine among the stumps of recently killed trees.
3. Replant. If trees need to be replaced, do not plant a pine. Use arborvitae or spruce.
Symptoms and Diagnosis
In the Spring, trees, aged 3 to 15 years, which have been infected for several years, show delayed bud break and reduced candle elongation. Mature foliage then fades, droops, and turns brown, in stark contrast to healthy trees nearby. Mortality appears to be at random with a few trees dying each year. Resin flow is visible at the tree base and is associated with a girdling chocolate brown to dark olive-brown canker under the bark. The trunk may be flattened on the affected side. Galleries of insects such as the pine root collar weevil may be found in the canker and provide a place for the fungus to sporulate. Weevils and other bark-infesting insects may serve as vectors for this disease. Although the fungus does not survive well in the soil, it may be spread by contaminated insects as they emerge from diseased trees and feed on healthy trees nearby.
Integrated Pest Management Strategies
1. Planting. Avoid planting eastern white pine on wet sites. Trees planted on wet sites seem to be more susceptible to the fungus. Excessively dry sites also seem to predispose trees to attack.
2. Sanitation. Remove and destroy infected trees including stumps, if possible. Do not replant eastern white pine among the stumps of recently killed trees.
3. Replant. If trees need to be replaced, do not plant a pine. Use arborvitae or spruce.
0
0
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.
0
0
文章
Dummer. ゛☀
2017年09月18日
Cytospora canker is caused by a fungus, Leucostoma kunzei (formerly known as Cytospora kunzei). In its perfect stage, it is known as Valsa kunzei. It is a destructive disease of many of the spruces, especially Colorado blue and Norway spruces, from the Midwest to New England. The disease is more common on trees over 15 years old and trees under stress and of low vigor. Trees with shallow roots, weakened by mechanical injury, insect, or weather stresses, and trees growing on unfavorable sites are most susceptible. The disease destroys the symmetry of spruce trees and in time may kill them. Infections on Colorado blue spruces are usually confined to branches. Branches and trunks are damaged on black, Engelmann, Norway, red, and white spruces. Cytospora cankers have also been found on Douglas fir, hemlock, larch, and balsam fir.
Symptoms and Diagnosis
Dying of lower branches is usually the first symptom. The needles turn brown and after a few months drop off, and white or light blue patches of resin become obvious on the dead bark of larger branches. As the disease progresses over several years, higher branches also die. Dead areas called cankers are formed. The infected inner bark tissue and cambium are brown in contrast to the normal light color of healthy tissue, but the wood beneath the infected bark is not discolored. As cankers enlarge and girdle the stem, parts above the diseased area lose color, make little growth, wilt or wither, and die back from the tips. Infected branches often start growth later in the spring. The resin exuded from cankered branches is visible on dead bark after infected needles are cast. This is the most obvious symptom on infected branches.
Life Cycle
The fungus overwinters in cankered bark. Spores from fruiting bodies formed in cankers are spread by rain, wind, insects, birds, and man. Infection occurs through wounds. The fungus grows and kills the bark, then expands until the entire branch is killed from the branch being girdled.
Integrated Pest Management Strategies
1. Prune out diseased branches. Prune out all infected branches and burn or remove them from the site. Prune in late winter when it is sunny and the trees are dry. Dip pruning tools into a solution of 1–part bleach and 9–parts water between cuts to reduce spreading the disease. After pruning, oil blades to prevent rust.
2. Avoid injuries to bark and stems. Wounds can provide entry points for the pathogen, especially during wet periods.
3.Improve plant health. Water during dry periods and aerate the soil around the tree to relieve soil compaction and facilitate water and nutrient penetration. Fertilize to maintain vigor.
4. Maintain good air circulation. Chances of infection are greater on plants that are crowded together. Space plants out when planting to accommodate mature growth.
5. Fungicidal sprays are seldom effective and are not recommended. Once the tree is infected, the disease is difficult to control. Bordeaux mixture or other copper-containing fungicides may help slow the spread of the disease. The best time to apply fungicides has not been established. Consider using fungicidal sprays only if the tree is very valuable and you are willing to pay for regular sprayings.
6. Remove the infected tree and plant a different species or variety. Blue and Norway spruce are most susceptible to Cytospora canker.
Symptoms and Diagnosis
Dying of lower branches is usually the first symptom. The needles turn brown and after a few months drop off, and white or light blue patches of resin become obvious on the dead bark of larger branches. As the disease progresses over several years, higher branches also die. Dead areas called cankers are formed. The infected inner bark tissue and cambium are brown in contrast to the normal light color of healthy tissue, but the wood beneath the infected bark is not discolored. As cankers enlarge and girdle the stem, parts above the diseased area lose color, make little growth, wilt or wither, and die back from the tips. Infected branches often start growth later in the spring. The resin exuded from cankered branches is visible on dead bark after infected needles are cast. This is the most obvious symptom on infected branches.
Life Cycle
The fungus overwinters in cankered bark. Spores from fruiting bodies formed in cankers are spread by rain, wind, insects, birds, and man. Infection occurs through wounds. The fungus grows and kills the bark, then expands until the entire branch is killed from the branch being girdled.
Integrated Pest Management Strategies
1. Prune out diseased branches. Prune out all infected branches and burn or remove them from the site. Prune in late winter when it is sunny and the trees are dry. Dip pruning tools into a solution of 1–part bleach and 9–parts water between cuts to reduce spreading the disease. After pruning, oil blades to prevent rust.
2. Avoid injuries to bark and stems. Wounds can provide entry points for the pathogen, especially during wet periods.
3.Improve plant health. Water during dry periods and aerate the soil around the tree to relieve soil compaction and facilitate water and nutrient penetration. Fertilize to maintain vigor.
4. Maintain good air circulation. Chances of infection are greater on plants that are crowded together. Space plants out when planting to accommodate mature growth.
5. Fungicidal sprays are seldom effective and are not recommended. Once the tree is infected, the disease is difficult to control. Bordeaux mixture or other copper-containing fungicides may help slow the spread of the disease. The best time to apply fungicides has not been established. Consider using fungicidal sprays only if the tree is very valuable and you are willing to pay for regular sprayings.
6. Remove the infected tree and plant a different species or variety. Blue and Norway spruce are most susceptible to Cytospora canker.
0
0
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.
0
0
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.
0
0
文章
Dummer. ゛☀
2017年09月17日
Peach leaf curl is a springtime disease caused by the fungus, Taphrina deformans. It infects the leaves and shoots of peaches and nectarines. Apricots are immune. It is one of the most common diseases of these fruits. It causes the leaves to curl and turn reddish in color. A severe infection can cause reduced yields. 
Symptoms and Diagnosis
Symptoms first appear in spring. New leaves become curled and develop reddish areas. The reddish areas become thickened and puckered resulting in severely distorted leaves. As the disease progresses, the thickened areas turn yellowish gray and become covered with velvety spores. Affected leaves turn yellow or brown and fall prematurely. Affected shoots usually send out new leaves which often are unaffected by the disease unless rainy weather ensues. In more severe infections, shoots may become thickened and die.
Aphids can also cause leaves to curl. If present, the insects or cast skins will be evident to the naked eye.
Life Cycle
The fungus overwinters on bud scales, on twigs, and on fallen infected leaves. In spring the fungal spores are splashed onto newly developing leaves. During cool, wet weather the spores germinate on the young leaves and initiate infection. Development of the disease slows as temperatures increase. Older leaves are resistant to infection. Consequently, the disease is most prevalent in the spring.
Integrated Pest Management Strategies
1. Keep plant healthy — avoid excess fertilization. A healthy plant can better withstand the loss of leaves, but excess fertilization can cause succulent tissue that is very susceptible to infection.
2. Clean up diseased leaves. Raking up and disposing of diseased leaves can't hurt, but its value in controlling the disease is slight.
3. Don't panic.Once infection has occurred fungicidal sprays are not effective. A healthy plant should refoliate. Because refoliation normally occurs during warmer, dryer weather, re-infection is usually not a problem. Thinning the fruit crop in years of severe infection can also help maintain plant vigor. To limit damage the year after a moderate to severe infection, follow the protective spray program below.
4. Use properly timed protective fungicidal sprays. If leaf curl was a problem in the spring, apply a protective fungicidal spray after leaf fall in October or November or before bud break in late winter, January through February. After buds have begun to swell fungicidal sprays are not satisfactory. Do not apply to foliage. Chemicals effective in controlling leaf curl include copper-based fungicides like Bordeaux mixture, Bravo, lime-sulfur spray, or other brands that list the control of peach leaf curl on their label.
5. Replace the tree with a more disease tolerant variety. If you want to avoid using fungicidal sprays, consider replacing the tree with a more tolerant variety. ‘Redhaven’ and cultivars derived from ‘Redhaven’ have greater tolerance to peach leaf curl disease.
Symptoms and Diagnosis
Symptoms first appear in spring. New leaves become curled and develop reddish areas. The reddish areas become thickened and puckered resulting in severely distorted leaves. As the disease progresses, the thickened areas turn yellowish gray and become covered with velvety spores. Affected leaves turn yellow or brown and fall prematurely. Affected shoots usually send out new leaves which often are unaffected by the disease unless rainy weather ensues. In more severe infections, shoots may become thickened and die.
Aphids can also cause leaves to curl. If present, the insects or cast skins will be evident to the naked eye.
Life Cycle
The fungus overwinters on bud scales, on twigs, and on fallen infected leaves. In spring the fungal spores are splashed onto newly developing leaves. During cool, wet weather the spores germinate on the young leaves and initiate infection. Development of the disease slows as temperatures increase. Older leaves are resistant to infection. Consequently, the disease is most prevalent in the spring.
Integrated Pest Management Strategies
1. Keep plant healthy — avoid excess fertilization. A healthy plant can better withstand the loss of leaves, but excess fertilization can cause succulent tissue that is very susceptible to infection.
2. Clean up diseased leaves. Raking up and disposing of diseased leaves can't hurt, but its value in controlling the disease is slight.
3. Don't panic.Once infection has occurred fungicidal sprays are not effective. A healthy plant should refoliate. Because refoliation normally occurs during warmer, dryer weather, re-infection is usually not a problem. Thinning the fruit crop in years of severe infection can also help maintain plant vigor. To limit damage the year after a moderate to severe infection, follow the protective spray program below.
4. Use properly timed protective fungicidal sprays. If leaf curl was a problem in the spring, apply a protective fungicidal spray after leaf fall in October or November or before bud break in late winter, January through February. After buds have begun to swell fungicidal sprays are not satisfactory. Do not apply to foliage. Chemicals effective in controlling leaf curl include copper-based fungicides like Bordeaux mixture, Bravo, lime-sulfur spray, or other brands that list the control of peach leaf curl on their label.
5. Replace the tree with a more disease tolerant variety. If you want to avoid using fungicidal sprays, consider replacing the tree with a more tolerant variety. ‘Redhaven’ and cultivars derived from ‘Redhaven’ have greater tolerance to peach leaf curl disease.
0
0
文章
Dummer. ゛☀
2017年09月17日
Gray mold of strawberries is caused by a fungus, Botrytis cinerea, which infects both the flowers and fruits. Because of this, Botrytis can greatly reduce fruit yields and is considered one of the most damaging diseases of strawberry. Botrytis is most prevalent during prolonged cool, wet weather during bloom and near harvest.
Symptoms and Diagnosis
Blossoms commonly turn brown and die. A soft, light brown rot may appear on any part of the berry, but generally occurs first in the area of the cap, destroying the berry within 48 hours. The infected fruit spot is at first a light brown color and somewhat soft in texture. As the entire berry becomes infected, the rotted area becomes firm and turns a darker brown color. Fruits soon "mummify" and, like the blossoms, become covered with a gray, dusty powder which are the spores of the Botrytis fungus. Berries resting on damp soil or touching infected plant parts are most commonly infected.
Life Cycle
Botrytis fungi overwinter as dark-colored, resting bodies (sclerotia) on dead tissue. In the spring during cool humid weather, spores form and spread by wind or water to wounded or extremely soft plant tissues. Infection can also occur from growth of fungal mycelium from previously infected plant parts. The fungus can survive on decaying vegetation so it can infect healthy plants throughout the growing season.
Integrated Pest Management Strategies
1. Remove infected plant parts. Collecting and removing infected plant parts can slow the spread of the disease. This should be done frequently especially during fruit bearing time.
2. Improve air circulation around the plants. Space plants widely and prune leaves so that adequate air flow may speed drying of the vegetation. Work with plants when they are dry.
3. Avoid spring applications of nitrogen fertilizer. High nitrogen levels promote excessive leaf growth and available surfaces for infection.
4. Harvest regularly. Remove and dispose of rotten or severely damaged fruit throughout the season.
5. Move plants to a better location.Select sites for planting that have good air circulation, are not shaded, and not subject to frost injury.
6. Use fungicide sprays, if necessary. Apply a fungicide at 5–10% bloom and at full bloom. Fungicides may be reapplied every 7–10 days during wet seasons. Pesticides registered for use include captan, chlorothalonil (Daconil), copper, iprodione (Chipco), mancozeb, sulfur, thiram, and ziram.
Symptoms and Diagnosis
Blossoms commonly turn brown and die. A soft, light brown rot may appear on any part of the berry, but generally occurs first in the area of the cap, destroying the berry within 48 hours. The infected fruit spot is at first a light brown color and somewhat soft in texture. As the entire berry becomes infected, the rotted area becomes firm and turns a darker brown color. Fruits soon "mummify" and, like the blossoms, become covered with a gray, dusty powder which are the spores of the Botrytis fungus. Berries resting on damp soil or touching infected plant parts are most commonly infected.
Life Cycle
Botrytis fungi overwinter as dark-colored, resting bodies (sclerotia) on dead tissue. In the spring during cool humid weather, spores form and spread by wind or water to wounded or extremely soft plant tissues. Infection can also occur from growth of fungal mycelium from previously infected plant parts. The fungus can survive on decaying vegetation so it can infect healthy plants throughout the growing season.
Integrated Pest Management Strategies
1. Remove infected plant parts. Collecting and removing infected plant parts can slow the spread of the disease. This should be done frequently especially during fruit bearing time.
2. Improve air circulation around the plants. Space plants widely and prune leaves so that adequate air flow may speed drying of the vegetation. Work with plants when they are dry.
3. Avoid spring applications of nitrogen fertilizer. High nitrogen levels promote excessive leaf growth and available surfaces for infection.
4. Harvest regularly. Remove and dispose of rotten or severely damaged fruit throughout the season.
5. Move plants to a better location.Select sites for planting that have good air circulation, are not shaded, and not subject to frost injury.
6. Use fungicide sprays, if necessary. Apply a fungicide at 5–10% bloom and at full bloom. Fungicides may be reapplied every 7–10 days during wet seasons. Pesticides registered for use include captan, chlorothalonil (Daconil), copper, iprodione (Chipco), mancozeb, sulfur, thiram, and ziram.
0
0
文章
Dummer. ゛☀
2017年09月17日
Downy mildew is an extremely serious fungal disease of grapes that can result in severe crop loss. It is caused by the fungus Plasmopara viticola.
Symptoms and Diagnosis
The pathogen attacks all green parts of the vine, especially the leaves. Lesions on leaves are angular, yellowish, sometimes oily, and located between the veins. As the disease progresses, a white cottony growth can be observed on the lower leaf surface.
Severely infected leaves will drop. If enough defoliation occurs, the overwintering buds will be more susceptible to winter injury. Infected shoot tips become thick, curl, and eventually turn brown and die. Young berries are highly susceptible, appearing grayish when infected. Berries become less susceptible when mature. Eventually, infected berries will drop.
Life Cycle
The fungus overwinters in diseased leaves on the ground. Spores are released in the spring and spread to the leaves and berries by splashing rain and wind. The fungus has two types of spores, both germinating into swimming spores. These spores swim to the stomates (breathing pores) of plants and initiate infection. Water is necessary for the spores to swim and infect, so outbreaks of the disease coincide with periods of wet weather. Downy mildew is favored by all factors that increase the moisture content of soil, air, and the plant, with rainfall being the principal factor for infection during the growing season. Downy mildew infection can become a severe problem when a wet winter is followed by a wet spring and a warm summer with frequent rainfall.
Integrated Pest Management Strategies
1. Maintain plant vigor. Make sure soils are welldrained. Fertilize according to soil test information obtained at least every other year.
2. Sanitation. Remove fallen leaves which are the source of overwintering inoculum.
3. Pruning. Prune out the ends of infected shoots.
4. Fungicides. Fungicides are an important control measure, especially on susceptible cultivars. They should be applied just before bloom, 7 to 10 days later (usually at the end of bloom), 10 to 14 days after that, and finally, 3 weeks after the third application. For cultivars very susceptible to downy mildew or where the disease was severe the previous season, an additional application is suggested about 2 weeks before the first blossom opens. Pesticides registered for use include captan, copper, fosetyl-Al, mancozeb, maneb, and ziram.
5. Cultivars. Select and plant resistant cultivars.
Symptoms and Diagnosis
The pathogen attacks all green parts of the vine, especially the leaves. Lesions on leaves are angular, yellowish, sometimes oily, and located between the veins. As the disease progresses, a white cottony growth can be observed on the lower leaf surface.
Severely infected leaves will drop. If enough defoliation occurs, the overwintering buds will be more susceptible to winter injury. Infected shoot tips become thick, curl, and eventually turn brown and die. Young berries are highly susceptible, appearing grayish when infected. Berries become less susceptible when mature. Eventually, infected berries will drop.
Life Cycle
The fungus overwinters in diseased leaves on the ground. Spores are released in the spring and spread to the leaves and berries by splashing rain and wind. The fungus has two types of spores, both germinating into swimming spores. These spores swim to the stomates (breathing pores) of plants and initiate infection. Water is necessary for the spores to swim and infect, so outbreaks of the disease coincide with periods of wet weather. Downy mildew is favored by all factors that increase the moisture content of soil, air, and the plant, with rainfall being the principal factor for infection during the growing season. Downy mildew infection can become a severe problem when a wet winter is followed by a wet spring and a warm summer with frequent rainfall.
Integrated Pest Management Strategies
1. Maintain plant vigor. Make sure soils are welldrained. Fertilize according to soil test information obtained at least every other year.
2. Sanitation. Remove fallen leaves which are the source of overwintering inoculum.
3. Pruning. Prune out the ends of infected shoots.
4. Fungicides. Fungicides are an important control measure, especially on susceptible cultivars. They should be applied just before bloom, 7 to 10 days later (usually at the end of bloom), 10 to 14 days after that, and finally, 3 weeks after the third application. For cultivars very susceptible to downy mildew or where the disease was severe the previous season, an additional application is suggested about 2 weeks before the first blossom opens. Pesticides registered for use include captan, copper, fosetyl-Al, mancozeb, maneb, and ziram.
5. Cultivars. Select and plant resistant cultivars.
0
0
文章
Dummer. ゛☀
2017年09月17日
Cane blight of raspberries is a late season disease caused by the fungus, Leptosphaeria conithyrium. Infected canes may blossom normally, but they usually wilt and die before they can set fruit or while they are heavy with fruit. Black raspberries are more susceptible than red or purple raspberries. Cankers on apples and roses are also caused by this fungus.
Symptoms and Diagnosis
Brown-purple areas develop around cuts or wounds in infected canes. The discoloration will slowly spread down the cane, encircling the stem. Small, smutty patches of olive-green fungal conidia (spores or conidiospores) develop on the bark. The spread of the disease through the canes blocks water movement through the plant, causing wilting and, eventually, death. Cane blight reduces yields because symptoms appear later in the growing season, when branches may be laden with fruit.
Life Cycle
Spores of the fungus overwinter on dead infected canes. In the late spring, fungal spores are spread from plant to plant by the wind and splashing water. Infection takes place when there is sufficient moisture allowing the spores to enter the plant through wounds. Spores may continue to live on dead, infected canes for 2 or more years.
Integrated Pest Management Strategies
1. Prune and destroy all infected stalks. Blighted canes cannot be cured.
2. Do any pruning work during dry weather to allow wounds to dry out and prevent infection by the fungal spores.
3. Prevent damage and wounds to canes by controlling cane borers. Vigorous, adequately fertilized and watered plants are more resistant to injury and less likely to attract harmful insects. If borers have infected canes, the tips will begin to wilt; prune these tips well below any insect punctures.
4. Plant resistant varieties. Red-fruited or purple varieties of raspberry are less susceptible to cane blight.
5. Use fungicides. Pesticides registered for use include copper and mancozeb.
Symptoms and Diagnosis
Brown-purple areas develop around cuts or wounds in infected canes. The discoloration will slowly spread down the cane, encircling the stem. Small, smutty patches of olive-green fungal conidia (spores or conidiospores) develop on the bark. The spread of the disease through the canes blocks water movement through the plant, causing wilting and, eventually, death. Cane blight reduces yields because symptoms appear later in the growing season, when branches may be laden with fruit.
Life Cycle
Spores of the fungus overwinter on dead infected canes. In the late spring, fungal spores are spread from plant to plant by the wind and splashing water. Infection takes place when there is sufficient moisture allowing the spores to enter the plant through wounds. Spores may continue to live on dead, infected canes for 2 or more years.
Integrated Pest Management Strategies
1. Prune and destroy all infected stalks. Blighted canes cannot be cured.
2. Do any pruning work during dry weather to allow wounds to dry out and prevent infection by the fungal spores.
3. Prevent damage and wounds to canes by controlling cane borers. Vigorous, adequately fertilized and watered plants are more resistant to injury and less likely to attract harmful insects. If borers have infected canes, the tips will begin to wilt; prune these tips well below any insect punctures.
4. Plant resistant varieties. Red-fruited or purple varieties of raspberry are less susceptible to cane blight.
5. Use fungicides. Pesticides registered for use include copper and mancozeb.
0
0
文章
Dummer. ゛☀
2017年09月17日
Black rot, caused by the fungus Guignardia bidwellii, is a serious disease of cultivated and wild grapes. The disease is most destructive in warm, wet seasons. It attacks all green parts of the vine – leaves, shoots, leaf and fruit stems, tendrils, and fruit. The most damaging effect is to the fruit. Note: Guignardia bidwellii forma parthenocissi causes a leaf spot on Boston ivy and Virginia creeper. Control is as for black rot of grapes.
Warm, muggy weather in the spring and summer, along with unsprayed fruit of susceptible varieties, may cause fruit to become almost completely rotted by harvest time. Black rot is not difficult to control if good cultural practices are followed along with the use of protective fungicide sprays.
Symptoms and Diagnosis
Leaves: Reddish brown and circular to angular spots appear on the upper surface of the leaves starting in late spring. As spots merge, they form irregular, reddish brown blotches. The number of spots or lesions per leaf varies from 2 to more than 100 depending on the severity of the disease. The center of the leaf spot turns tannish brown and is surrounded by a black margin. Black, speck-sized fruiting bodies (pycnidia) are arranged in a definite ring just inside the margin of the lesion. Only young, rapidly growing leaves are affected.
Fruit: Shortly after the flower petals fall, fruit infection can occur. Most infections start when the fruit is half to almost full size. A small spot will appear that becomes circular and whitish tan, often surrounded by a brown ring. This happens while the berry is still green. The spots grow rapidly and may cover half of the berry within 48 hours. Within a few days the entire berry becomes coal black, hard, and mummified. The surface of the withered fruit is soon covered with minute, black, pimple-like, sporeproducing pycnidia that are arranged in circular zones.
Life Cycle
The black rot fungus overwinters in canes, tendrils, and leaves on the grape vine and on the ground. Mummified berries on the ground or those that are still clinging to the vines become the major infection source the following spring. During rain, microscopic spores (ascospores) are shot out of numerous, black fruiting bodies (perithecia) and are carried by air currents to young, expanding leaves. In the presence of moisture, these spores germinate in 36 to 48 hours and eventually penetrate the leaves and fruit stems. The infection becomes visible after 8 to 25 days. When the weather is wet, spores can be released the entire spring and summer providing continuous infection. Cool weather slows growth of the fungus. It requires warm weather for optimal growth and a period of 2 to 3 days of rain, drizzle, or fog.
New black rot infections continue into late spring and summer during prolonged periods of warm, rainy weather. During August, the pycnidia are transformed into the overwintering stage (pycnosclerotia) that gives rise to perithecia within which the spring ascospores are produced, completing the disease cycle.
Integrated Pest Management Strategies
1. Planting. Space vines properly and choose a planting site where the vines will be exposed to full sun and good air circulation. Keep the vines off the ground and insure they are properly tied, limiting the amount of time the vines remain wet thus reducing infection.
2. Sanitation. Keep the fruit planting and surrounding areas free of weeds and tall grass. This practice will promote lower relative humidity and rapid drying of vines and thereby limit fungal infection.
3. Pruning. Prune the vines in early winter during dormancy. Select only a few strong, healthy canes from the previous year’s growth to produce the following season’s crop. Remove these prunings from the vineyard and burn or destroy.
4. Cultivation. Cultivate the vineyard before budbreak to bury the mummified berries. Diseased berries covered with soil do not produce spores that will reach the developing vines. For homegrown grapes, use 2–3 inches of leaf mulch or fine bark to cover infected debris.
5. Fungicides. Use protective fungicide sprays. Pesticides registered to protect the developing new growth include copper, captan, ferbam, mancozeb, maneb, triadimefon, and ziram. Important spraying times are as new shoots are 2 to 4 inches long, and again when they are 10 to 15 inches long, just before bloom, just after bloom, and when the fruit has set.
6. Cultivars. Cultivars with large, juicy berries are the most susceptible. In general, grapes that ripen late in the season are affected the least. Most commercial cultivars are sufficiently resistant if adequately protected with a fungicide spray program.
Warm, muggy weather in the spring and summer, along with unsprayed fruit of susceptible varieties, may cause fruit to become almost completely rotted by harvest time. Black rot is not difficult to control if good cultural practices are followed along with the use of protective fungicide sprays.
Symptoms and Diagnosis
Leaves: Reddish brown and circular to angular spots appear on the upper surface of the leaves starting in late spring. As spots merge, they form irregular, reddish brown blotches. The number of spots or lesions per leaf varies from 2 to more than 100 depending on the severity of the disease. The center of the leaf spot turns tannish brown and is surrounded by a black margin. Black, speck-sized fruiting bodies (pycnidia) are arranged in a definite ring just inside the margin of the lesion. Only young, rapidly growing leaves are affected.
Fruit: Shortly after the flower petals fall, fruit infection can occur. Most infections start when the fruit is half to almost full size. A small spot will appear that becomes circular and whitish tan, often surrounded by a brown ring. This happens while the berry is still green. The spots grow rapidly and may cover half of the berry within 48 hours. Within a few days the entire berry becomes coal black, hard, and mummified. The surface of the withered fruit is soon covered with minute, black, pimple-like, sporeproducing pycnidia that are arranged in circular zones.
Life Cycle
The black rot fungus overwinters in canes, tendrils, and leaves on the grape vine and on the ground. Mummified berries on the ground or those that are still clinging to the vines become the major infection source the following spring. During rain, microscopic spores (ascospores) are shot out of numerous, black fruiting bodies (perithecia) and are carried by air currents to young, expanding leaves. In the presence of moisture, these spores germinate in 36 to 48 hours and eventually penetrate the leaves and fruit stems. The infection becomes visible after 8 to 25 days. When the weather is wet, spores can be released the entire spring and summer providing continuous infection. Cool weather slows growth of the fungus. It requires warm weather for optimal growth and a period of 2 to 3 days of rain, drizzle, or fog.
New black rot infections continue into late spring and summer during prolonged periods of warm, rainy weather. During August, the pycnidia are transformed into the overwintering stage (pycnosclerotia) that gives rise to perithecia within which the spring ascospores are produced, completing the disease cycle.
Integrated Pest Management Strategies
1. Planting. Space vines properly and choose a planting site where the vines will be exposed to full sun and good air circulation. Keep the vines off the ground and insure they are properly tied, limiting the amount of time the vines remain wet thus reducing infection.
2. Sanitation. Keep the fruit planting and surrounding areas free of weeds and tall grass. This practice will promote lower relative humidity and rapid drying of vines and thereby limit fungal infection.
3. Pruning. Prune the vines in early winter during dormancy. Select only a few strong, healthy canes from the previous year’s growth to produce the following season’s crop. Remove these prunings from the vineyard and burn or destroy.
4. Cultivation. Cultivate the vineyard before budbreak to bury the mummified berries. Diseased berries covered with soil do not produce spores that will reach the developing vines. For homegrown grapes, use 2–3 inches of leaf mulch or fine bark to cover infected debris.
5. Fungicides. Use protective fungicide sprays. Pesticides registered to protect the developing new growth include copper, captan, ferbam, mancozeb, maneb, triadimefon, and ziram. Important spraying times are as new shoots are 2 to 4 inches long, and again when they are 10 to 15 inches long, just before bloom, just after bloom, and when the fruit has set.
6. Cultivars. Cultivars with large, juicy berries are the most susceptible. In general, grapes that ripen late in the season are affected the least. Most commercial cultivars are sufficiently resistant if adequately protected with a fungicide spray program.
0
0
文章
Dummer. ゛☀
2017年09月17日
The fungus, Armillaria mellea, occurs sporadically in this region and has been reported to infect over 25 species of ornamental trees and shrubs. The most distinctive sign of Armillaria infection is the honeycolored mushroom that grows from the roots and base of plants. The fungus is especially prevalent on oak but also affects many different kinds of fruit and nut trees, ornamentals, and herbaceous plantings. It is often referred to as oak root rot fungus because it is commonly found on oaks or in areas where oaks trees once were grown, such as cleared forest land.
Symptoms and Diagnosis
The symptoms of Armillaria are similar to those of other root disorders; height growth is reduced, foliage is sparse, and leaves that remain on plants are stunted and yellow. An abnormal flow of sap may be visible on the root collar. When soil is removed from the base of the trunk, black, root-like strands are visible and attached to larger roots. White to dark, fan-shaped mats of fungal strands develop between the bark and wood in infected root and trunk tissues. The most positive sign of infection is the production of clusters of honey-colored mushrooms at the base of the tree near the soil line. The mushrooms may have stalks 4 to 6 inches high with caps 1 inch high and 2 to 4 inches wide.
Life Cycle
Armillaria is found in the soil sporadically throughout the Midwest. The fungus spreads primarily by root-to-root contact or by root-like fungal strands. Root-like fungal strands grow through the soil and adhere to the host roots or root collar that it encounters. Successfully attacked trees do not die until infections girdle the base of the tree. On healthy, vigorous trees, Armillaria is not lethal but if present, it may begin to grow when the tree dies of other causes. Young trees are more likely to be killed by Armillaria. Trees that are 15–20 years old are more tolerant to attack.
Integrated Pest Management Strategies
1. Remove and destroy infected material. Remove as much of the stump as possible. Sterilize tools with a solution of 1–part bleach with 9–parts water after use.
2. Provide adequate moisture in a well-drained soil to maintain vigor and resistance to infection. Plants suffering from drought are extremely susceptible to infection. Fertilize trees appropriately in late winter or early spring.
3. No effective chemical controls are known. Plants reported by Auburn University to be resistant to Armillaria root rot include ginkgo, tulip tree, ash, bald cypress, cherry, Chinese elm, Chinese pistache, crabapple, cryptomeria, dawn redwood, eucalyptus, hackberry, holly, incense cedar, Leyland cypress, maidenhair tree, maple, privet, smoke tree, sweetgum, tree-ofheaven, white fir, and wisteria. These should be considered for replacement of diseased trees. New soil should be used to amend the planting site. All diseased material and associated roots, as much as possible, should be excavated before replanting.
Symptoms and Diagnosis
The symptoms of Armillaria are similar to those of other root disorders; height growth is reduced, foliage is sparse, and leaves that remain on plants are stunted and yellow. An abnormal flow of sap may be visible on the root collar. When soil is removed from the base of the trunk, black, root-like strands are visible and attached to larger roots. White to dark, fan-shaped mats of fungal strands develop between the bark and wood in infected root and trunk tissues. The most positive sign of infection is the production of clusters of honey-colored mushrooms at the base of the tree near the soil line. The mushrooms may have stalks 4 to 6 inches high with caps 1 inch high and 2 to 4 inches wide.
Life Cycle
Armillaria is found in the soil sporadically throughout the Midwest. The fungus spreads primarily by root-to-root contact or by root-like fungal strands. Root-like fungal strands grow through the soil and adhere to the host roots or root collar that it encounters. Successfully attacked trees do not die until infections girdle the base of the tree. On healthy, vigorous trees, Armillaria is not lethal but if present, it may begin to grow when the tree dies of other causes. Young trees are more likely to be killed by Armillaria. Trees that are 15–20 years old are more tolerant to attack.
Integrated Pest Management Strategies
1. Remove and destroy infected material. Remove as much of the stump as possible. Sterilize tools with a solution of 1–part bleach with 9–parts water after use.
2. Provide adequate moisture in a well-drained soil to maintain vigor and resistance to infection. Plants suffering from drought are extremely susceptible to infection. Fertilize trees appropriately in late winter or early spring.
3. No effective chemical controls are known. Plants reported by Auburn University to be resistant to Armillaria root rot include ginkgo, tulip tree, ash, bald cypress, cherry, Chinese elm, Chinese pistache, crabapple, cryptomeria, dawn redwood, eucalyptus, hackberry, holly, incense cedar, Leyland cypress, maidenhair tree, maple, privet, smoke tree, sweetgum, tree-ofheaven, white fir, and wisteria. These should be considered for replacement of diseased trees. New soil should be used to amend the planting site. All diseased material and associated roots, as much as possible, should be excavated before replanting.
0
0
文章
Dummer. ゛☀
2017年09月16日
Powdery mildew is caused by a fungus and is seen as a light gray or whitish powder on the surface of leaves. It occurs following warm days and cool nights often being seen in the fall and spring. The disease is considered more unsightly than harmful. Death of the plant is rare.
Symptoms and Diagnosis
Even though each species of powdery mildew attacks only a narrow range of hosts, there are 11,000 species of the powdery mildew fungi, and many ornamentals are hosts. Superficial powdery patches appear on leaf surfaces, young stems, flowers, and even fruit. The powder is composed of mycelium and colorless chains of spores on upright stalks. Later there may be dark "pepper-like" spots among the powder (the spots are spore-producing bodies). As the disease progresses, leaves may be dwarfed, curl, turn yellow, and drop off. Flowers may be deformed. Fruit crops may be reduced, with the fruit misshapen and covered with powdery patches.
Life Cycle
Powdery mildew commonly winters over as mycelial mats in dormant buds or on plant stems and fallen leaves. During humid and warm spring weather (with cool nights), infected buds open and spread conidia (spores) to new host tissue. These conidia do not require free moisture in order to germinate as many fungi do. A new generation may be produced every 72 hours, if conditions are right.
Integrated Pest Management Strategies
1. Purchase resistant varieties. This is the best strategy for avoiding powdery mildew.
2. Pruning. Prune out diseased tissue and destroy it. Gather and destroy dead leaves and stems in the fall. This is the source of next season’s inoculum.
3. Keep plants in good vigor. Space the plants for good air circulation. Give the plants plenty of sun, as too much shade seems to make the problem worse. Try to avoid overhead watering and do not handle the plant when the foliage is wet as this will spread the disease. Water early in the day.
4. Fungicides. Use fungicides as a preventive treatment before a rain for maximum protection. Spray both sides of leaves and flowers well with sulfur, mancozeb, maneb, chlorothalonil (Daconil), cinnamaldehyde (Cinnamite), or copper-containing fungicides.
Symptoms and Diagnosis
Even though each species of powdery mildew attacks only a narrow range of hosts, there are 11,000 species of the powdery mildew fungi, and many ornamentals are hosts. Superficial powdery patches appear on leaf surfaces, young stems, flowers, and even fruit. The powder is composed of mycelium and colorless chains of spores on upright stalks. Later there may be dark "pepper-like" spots among the powder (the spots are spore-producing bodies). As the disease progresses, leaves may be dwarfed, curl, turn yellow, and drop off. Flowers may be deformed. Fruit crops may be reduced, with the fruit misshapen and covered with powdery patches.
Life Cycle
Powdery mildew commonly winters over as mycelial mats in dormant buds or on plant stems and fallen leaves. During humid and warm spring weather (with cool nights), infected buds open and spread conidia (spores) to new host tissue. These conidia do not require free moisture in order to germinate as many fungi do. A new generation may be produced every 72 hours, if conditions are right.
Integrated Pest Management Strategies
1. Purchase resistant varieties. This is the best strategy for avoiding powdery mildew.
2. Pruning. Prune out diseased tissue and destroy it. Gather and destroy dead leaves and stems in the fall. This is the source of next season’s inoculum.
3. Keep plants in good vigor. Space the plants for good air circulation. Give the plants plenty of sun, as too much shade seems to make the problem worse. Try to avoid overhead watering and do not handle the plant when the foliage is wet as this will spread the disease. Water early in the day.
4. Fungicides. Use fungicides as a preventive treatment before a rain for maximum protection. Spray both sides of leaves and flowers well with sulfur, mancozeb, maneb, chlorothalonil (Daconil), cinnamaldehyde (Cinnamite), or copper-containing fungicides.
0
0
文章
Dummer. ゛☀
2017年09月16日
Leaf spots on English ivy are caused by either a bacterium, Xanthomonas campestris, or a fungus, Colletotrichum trichellum. Both can cause defoliation, but the fungal leaf spot is more active in causing stem infection.
Symptoms and Diagnosis
Bacterial leaf spot first begins as light green, watersoaked spots that enlarge and become brown or brownish black in the center. On mature leaves the margin of the spot may be red. An infection in the leaf petiole causes the petiole to become black. Infection can move into the stem causing tips to turn black and die.
The fungal leaf spot produces large tan to brown spots on the leaves. They do not have a red margin. Black specks, fungal fruiting bodies, may be visible in the dead tissue, giving the spots a speckled appearance. The fungus can also infect stems, resulting in tip dieback.
Integrated Pest Management Strategies
1. Remove and destroy infected leaves and stems. Regardless of whether the spots were caused by a bacterial or fungal pathogen, removing diseased leaves will slow the spread of the disease.
2. Avoid wetting the foliage. Wetting the foliage, especially in late afternoon or evening, facilitates the development and spread of leaf spot organisms. Water early in the morning so the foliage dries before night.
3. Prune out and destroy all diseased plant parts in the fall. Thin the planting to allow better air movement and promote drying.
4. Live with the disease. The above cultural practices are generally sufficient to keep the disease from becoming a major problem.
5. Use fungicides. Sprays can be effective against both bacterial and fungal leaf spot diseases. They must be applied on a regular schedule and reapplied if rainfall is prevalent. copper fungicides are generally effective in controlling both leaf spots.
Symptoms and Diagnosis
Bacterial leaf spot first begins as light green, watersoaked spots that enlarge and become brown or brownish black in the center. On mature leaves the margin of the spot may be red. An infection in the leaf petiole causes the petiole to become black. Infection can move into the stem causing tips to turn black and die.
The fungal leaf spot produces large tan to brown spots on the leaves. They do not have a red margin. Black specks, fungal fruiting bodies, may be visible in the dead tissue, giving the spots a speckled appearance. The fungus can also infect stems, resulting in tip dieback.
Integrated Pest Management Strategies
1. Remove and destroy infected leaves and stems. Regardless of whether the spots were caused by a bacterial or fungal pathogen, removing diseased leaves will slow the spread of the disease.
2. Avoid wetting the foliage. Wetting the foliage, especially in late afternoon or evening, facilitates the development and spread of leaf spot organisms. Water early in the morning so the foliage dries before night.
3. Prune out and destroy all diseased plant parts in the fall. Thin the planting to allow better air movement and promote drying.
4. Live with the disease. The above cultural practices are generally sufficient to keep the disease from becoming a major problem.
5. Use fungicides. Sprays can be effective against both bacterial and fungal leaf spot diseases. They must be applied on a regular schedule and reapplied if rainfall is prevalent. copper fungicides are generally effective in controlling both leaf spots.
1
0
文章
Dummer. ゛☀
2017年09月16日
Botrytis blight on peony foliage (Paeonia)
Gray mold or botrytis blight is caused by the fungus, Botrytis paeoniae. It is the most common disease of garden peonies. This destructive disease is very prevalent during damp, rainy seasons.
Symptoms and Diagnosis
On peonies afflicted with botrytis, the young shoots rot off at ground level when they are 5 to 8 inches tall. The stems often have a water-soaked, cankerous appearance. The leafy shoots wilt suddenly and fall over. The rotted portion of the plant will become covered with a soft brown or blackish mass of spores. Just above the ground level, the stalk will be covered with a gray mold which sheds large numbers of spores. The spores are carried by wind and insects to young leaves and flower buds and cause a leaf blight and bud rot. Small buds that are affected turn black and wither. Larger buds turn brown and fail to open. During a severe outbreak of the disease, 90% of the buds fail to develop. Open flowers are affected occasionally, and they also turn brown and later develop a covering of gray mold.
Life Cycle
Botrytis fungi are both saprophytic and parasitic. The spore-producing structures of the fungus develop along the base of the rotting stalks and survive in debris left in the garden over the winter. In the spring, spores form and spread to dying, wounded, or extremely soft plant tissues. As the disease progresses, a gray mold develops. The gray mold is made up of spores that are either wind-blown or splashed onto new tissues and infect.
Integrated Pest Management Strategies
1. Prevent infection. In early fall, cut down all old leaves and stalks to ground level. This debris should be destroyed and not composted. Apply 1 to 2 inches of mulch to bury debris.
2. Improve soil drainage. Plant peonies in welldrained soil; heavy clay soils should be lightened with organic material such as compost or peat moss. They should not be planted so that water is apt to cover their bases, nor should soil be heaped about the leaf bases.
3. Move plants to a better location. Good air circulation can reduce disease problems. Plant in full sun or at least in part sun. Space plants widely, at least 3 feet apart. Remove aging leaves from plants.
4.Use disease-free roots. When planting new plants, buy only from reputable dealers, or take divisions only from healthy, disease-free plants.
5. Use a fungicide. Spray the plants with a fungicide when young tips break through the ground. Follow 2 weeks later with another application and every 14 days thereafter until mid-June. Pesticides registered for use include copper, captan, chlorothalonil (Daconil), mancozeb, maneb, sulfur, and thiophanate methyl (Cleary 3336). Fungicides must be applied in advance of the disease as a protectant.
6. Look for varieties that show some resistance to the disease.
Gray mold or botrytis blight is caused by the fungus, Botrytis paeoniae. It is the most common disease of garden peonies. This destructive disease is very prevalent during damp, rainy seasons.
Symptoms and Diagnosis
On peonies afflicted with botrytis, the young shoots rot off at ground level when they are 5 to 8 inches tall. The stems often have a water-soaked, cankerous appearance. The leafy shoots wilt suddenly and fall over. The rotted portion of the plant will become covered with a soft brown or blackish mass of spores. Just above the ground level, the stalk will be covered with a gray mold which sheds large numbers of spores. The spores are carried by wind and insects to young leaves and flower buds and cause a leaf blight and bud rot. Small buds that are affected turn black and wither. Larger buds turn brown and fail to open. During a severe outbreak of the disease, 90% of the buds fail to develop. Open flowers are affected occasionally, and they also turn brown and later develop a covering of gray mold.
Life Cycle
Botrytis fungi are both saprophytic and parasitic. The spore-producing structures of the fungus develop along the base of the rotting stalks and survive in debris left in the garden over the winter. In the spring, spores form and spread to dying, wounded, or extremely soft plant tissues. As the disease progresses, a gray mold develops. The gray mold is made up of spores that are either wind-blown or splashed onto new tissues and infect.
Integrated Pest Management Strategies
1. Prevent infection. In early fall, cut down all old leaves and stalks to ground level. This debris should be destroyed and not composted. Apply 1 to 2 inches of mulch to bury debris.
2. Improve soil drainage. Plant peonies in welldrained soil; heavy clay soils should be lightened with organic material such as compost or peat moss. They should not be planted so that water is apt to cover their bases, nor should soil be heaped about the leaf bases.
3. Move plants to a better location. Good air circulation can reduce disease problems. Plant in full sun or at least in part sun. Space plants widely, at least 3 feet apart. Remove aging leaves from plants.
4.Use disease-free roots. When planting new plants, buy only from reputable dealers, or take divisions only from healthy, disease-free plants.
5. Use a fungicide. Spray the plants with a fungicide when young tips break through the ground. Follow 2 weeks later with another application and every 14 days thereafter until mid-June. Pesticides registered for use include copper, captan, chlorothalonil (Daconil), mancozeb, maneb, sulfur, and thiophanate methyl (Cleary 3336). Fungicides must be applied in advance of the disease as a protectant.
6. Look for varieties that show some resistance to the disease.
0
0
文章
Dummer. ゛☀
2017年09月15日
Botrytis infects plant material above ground which is usually dead or dying. Depending on the species of the plant and the fungus there may be different symptoms at different times of year. A common sign of botrytis is a grey mould on leaves, stems, fruits, flowers and buds. Before the mould appears symptoms include dead brown patches on leaves, stems and buds, white or pale brown spots on petals and fruit, and rotting on unplanted bulbs.
Plants affected
Most fruit and vegetables, some houseplants, ornamentals, shrubs and trees.
About Grey mould
There are many species of botrytis with different infection methods. They cause a range of symptoms before the fuzzy grey mould appears including dead brown patches on leaves, stems and buds, white or pale brown spots on petals and fruit, and rotting on unplanted bulbs.
The spores will attack weak or dying plants in preference to healthy ones.
Conditions must be cool and humid for plants to be infected.
The fungal phase can only survive a narrow range of temperatures.
Botrytis overwinters as small, dark, hard structures, called sclerotia, on plant debris and other surfaces.
When spring weather conditions are favourable they produce spores. These are dispersed by wind, air movement, water splash and pesticide sprays.
Once a plant is infected, botrytis may spread to all parts depending on its species and variety.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Grey mould
Myclobutanil
Penconazole
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regular observation is essential to prevent infections establishing.
Remove all dead and injured plant material before it can become infected.
Remove infected leaves, fruits and buds by cutting right back into healthy growth. Bin or burn the infected material to help reduce the spread of infection.
Isolate infected plants to reduce infection spread.
Place fleece between plants to reduce the movement of spores.
Prevention
Regularly check plants for signs of infection and deal with them as soon as they appear.
Ensure greenhouses are always well ventilated.
Space plants out to reduce the humidity around them and prevent infections establishing.
Reduce the humidity in greenhouses and around houseplants to prevent infections establishing.
Plants affected
Most fruit and vegetables, some houseplants, ornamentals, shrubs and trees.
About Grey mould
There are many species of botrytis with different infection methods. They cause a range of symptoms before the fuzzy grey mould appears including dead brown patches on leaves, stems and buds, white or pale brown spots on petals and fruit, and rotting on unplanted bulbs.
The spores will attack weak or dying plants in preference to healthy ones.
Conditions must be cool and humid for plants to be infected.
The fungal phase can only survive a narrow range of temperatures.
Botrytis overwinters as small, dark, hard structures, called sclerotia, on plant debris and other surfaces.
When spring weather conditions are favourable they produce spores. These are dispersed by wind, air movement, water splash and pesticide sprays.
Once a plant is infected, botrytis may spread to all parts depending on its species and variety.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Grey mould
Myclobutanil
Penconazole
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regular observation is essential to prevent infections establishing.
Remove all dead and injured plant material before it can become infected.
Remove infected leaves, fruits and buds by cutting right back into healthy growth. Bin or burn the infected material to help reduce the spread of infection.
Isolate infected plants to reduce infection spread.
Place fleece between plants to reduce the movement of spores.
Prevention
Regularly check plants for signs of infection and deal with them as soon as they appear.
Ensure greenhouses are always well ventilated.
Space plants out to reduce the humidity around them and prevent infections establishing.
Reduce the humidity in greenhouses and around houseplants to prevent infections establishing.
0
0
