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.
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文章
Dummer. ゛☀
2017年09月16日
Distorted flowers on purple coneflower (Echinacea purpurea) caused by aster yellows
Aster yellows is a viral-like disease caused by a phytoplasma (formerly called a mycoplasma-like organism). Insects that suck the sap of plants, especially the aster leafhopper, vector the disease. Aster leafhoppers are insects that annually migrate northward from their winter home in areas along the Gulf of Mexico. Aster yellows is a disease that affects over 300 species of plants, including ornamentals such as aster, coneflower, zinnia, marigold, chrysanthemum, petunia, and snapdragon. Edibles affected include lettuce, carrot, tomato, and celery. Grasses and grains also are hosts. Weeds that may harbor the disease include plantain, dandelion, and other broad-leafed weeds.
Aster yellows is primarily transmitted by leafhoppers. When a leafhopper feeds on a plant infected with aster yellows it becomes "infected" with the phytoplasma and remains infected throughout its life. The phytoplasma cells multiply and cause infection of the insect’s salivary glands within one to three weeks. When the infected insects feed on healthy plants, they inject the phytoplasma cells into the plant phloem. Susceptible plants will be symptomatic in 10 to 40 days.
The spread of aster yellows is worse in cool, wet summers. Hot dry weather is not favorable for either the phytoplasma or the leafhopper. As with many disease and pest problems, diagnosis is perhaps the most important factor in controlling aster yellows.
A somewhat similar appearing problem on coneflowers is caused by an eriophyid mite. Experts are still sorting this problem out but the lower pictures on this page may be caused by this yet unnamed eriophyid mite. At present the common name used for this disorder is coneflower rosette mite. It may be a controllable problem through sanitation practices (disposal of all affected flowers as they appear and all foliage in the fall) unlike aster yellows for which there is no cure other than to destroy infected plants.
Symptoms and Diagnosis
Chlorosis, yellowing of the leaves while the veins remain green, is a major symptom of aster yellows. Growth slows down and leaves may be smaller and more narrow than usual. Foliage is sometimes curled. Flowers may be deformed and exhibit bizarre tufts of deformed leaves inside the flower or in place of the flower. Flowers may not produce seeds. The symptoms of the disease will often differ depending upon what species is infected. For instance, carrot roots may be bitter and hairy while lettuce may show pink or tan spots and have twisted inner leaves.
Integrated Pest Management Strategies
1. Remove diseased plants. Once a plant is infected with aster yellows, it is a lost cause since the disease is incurable. Early diagnosis and prompt removal of infected plants may help reduce the spread of the disease. Although the disease itself is not fatal to the plant, its presence makes it impossible for a plant to fulfill its intended role in the garden.
2. Plant less susceptible plant species. Controlling aster yellows is difficult. As long as infected leafhoppers are around, they can infect plants. A practical way to avoid having problems with this disease is to grow plants that are not as susceptible to aster yellows. Verbena, salvia, nicotiana, geranium, cockscomb, and impatiens are among the least susceptible plants.
3. Control insects. Vegetable growers may protect susceptible crops by using the mesh fabrics that keep leafhoppers and other insects away from the plants. Some growers put strips of aluminum foil between rows because bright reflections of sunlight confuse the leafhoppers.
4. Control weeds. Remove weeds in your lawn, garden, and surrounding areas, including plantain and dandelion that may harbor the disease.
Aster yellows is a viral-like disease caused by a phytoplasma (formerly called a mycoplasma-like organism). Insects that suck the sap of plants, especially the aster leafhopper, vector the disease. Aster leafhoppers are insects that annually migrate northward from their winter home in areas along the Gulf of Mexico. Aster yellows is a disease that affects over 300 species of plants, including ornamentals such as aster, coneflower, zinnia, marigold, chrysanthemum, petunia, and snapdragon. Edibles affected include lettuce, carrot, tomato, and celery. Grasses and grains also are hosts. Weeds that may harbor the disease include plantain, dandelion, and other broad-leafed weeds.
Aster yellows is primarily transmitted by leafhoppers. When a leafhopper feeds on a plant infected with aster yellows it becomes "infected" with the phytoplasma and remains infected throughout its life. The phytoplasma cells multiply and cause infection of the insect’s salivary glands within one to three weeks. When the infected insects feed on healthy plants, they inject the phytoplasma cells into the plant phloem. Susceptible plants will be symptomatic in 10 to 40 days.
The spread of aster yellows is worse in cool, wet summers. Hot dry weather is not favorable for either the phytoplasma or the leafhopper. As with many disease and pest problems, diagnosis is perhaps the most important factor in controlling aster yellows.
A somewhat similar appearing problem on coneflowers is caused by an eriophyid mite. Experts are still sorting this problem out but the lower pictures on this page may be caused by this yet unnamed eriophyid mite. At present the common name used for this disorder is coneflower rosette mite. It may be a controllable problem through sanitation practices (disposal of all affected flowers as they appear and all foliage in the fall) unlike aster yellows for which there is no cure other than to destroy infected plants.
Symptoms and Diagnosis
Chlorosis, yellowing of the leaves while the veins remain green, is a major symptom of aster yellows. Growth slows down and leaves may be smaller and more narrow than usual. Foliage is sometimes curled. Flowers may be deformed and exhibit bizarre tufts of deformed leaves inside the flower or in place of the flower. Flowers may not produce seeds. The symptoms of the disease will often differ depending upon what species is infected. For instance, carrot roots may be bitter and hairy while lettuce may show pink or tan spots and have twisted inner leaves.
Integrated Pest Management Strategies
1. Remove diseased plants. Once a plant is infected with aster yellows, it is a lost cause since the disease is incurable. Early diagnosis and prompt removal of infected plants may help reduce the spread of the disease. Although the disease itself is not fatal to the plant, its presence makes it impossible for a plant to fulfill its intended role in the garden.
2. Plant less susceptible plant species. Controlling aster yellows is difficult. As long as infected leafhoppers are around, they can infect plants. A practical way to avoid having problems with this disease is to grow plants that are not as susceptible to aster yellows. Verbena, salvia, nicotiana, geranium, cockscomb, and impatiens are among the least susceptible plants.
3. Control insects. Vegetable growers may protect susceptible crops by using the mesh fabrics that keep leafhoppers and other insects away from the plants. Some growers put strips of aluminum foil between rows because bright reflections of sunlight confuse the leafhoppers.
4. Control weeds. Remove weeds in your lawn, garden, and surrounding areas, including plantain and dandelion that may harbor the disease.
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文章
Dummer. ゛☀
2017年09月16日
Alternaria blight on zinnia (Zinnia) - left leaf; bacterial leaf spot on zinnia - right leaf
Only two diseases are commonly troublesome on zinnias (Zinnia elegans), powdery mildew and Alternaria blight. Alternaria blight is the most common and conspicuous.
Symptoms and Diagnosis
Spotting of the foliage caused by the fungus, Alternaria zinniae, is the most conspicuous symptom of zinnia blight. Individual spots are at first circular in outline but rapidly become irregular. The spots may vary from 2 to 10 millimeters or more in diameter, are reddish brown, and have grayish-white centers on the upper leaf surface. Differentiation of margin and center is lacking on the lower surface. As the spots increase in size and number, they coalesce and the affected leaves become brown and dry.
Blossoms may be severely affected. Brown spots, 1 or 2 millimeters in diameter, with grayish-white centers sometimes appear on the petal tissues of the ray flowers. Affected plants soon darken and wither, causing blossoms to become unsightly.
Numerous, small, reddish spots, sometimes with grayish-white centers, may be seen on stem internodes. Such spots usually are superficial. Spots that develop at nodes, however, usually do not remain superficial. Instead, they grow or coalesce into larger lesions that frequently girdle the stem causing the upper portions of the affected stem to die back to the node. Dark brown to black cankers with sunken centers are also common at the base of the stem of diseased plants. Affected plants often wilt completely, even when the basal cankers do not encircle the stem.
The outer tissues of affected roots may become dark gray, rot completely, and slough off, resulting in wilting and death of the plant. Damping-off of seedlings also may occur.
Life Cycle
The fungus survives on seeds and in the soil associated with host debris. Midsummer and early fall are normal times of outbreak.
Integrated Pest Management Strategies
1. Sanitation. Clean up debris; bury or burn if possible. Fungus may remain associated with plant material for 2 years.
2. Rotation. Use a long crop rotation of three years if growing commercially. A two-year rotation schedule is satisfactory for home garden and small isolated areas where disease spread can be limited.
3. Resistant varieties. Use resistant varieties of Zinnia elegans when possible. But be warned, no cultivars to date have been found to be totally resistant to Alternaria blight.
4. Propagation. Seeds may be infected with the fungus. Before planting, treat the seeds by placing them in hot water at 125 degrees F for 30 minutes. Then cool and dry. Older seeds can be injured by this treatment.
5. Watering. Do not use overhead irrigation. Water at the base of plants.
6. Fungicides. Use protectant fungicides. Spray seedlings and young plants with azoxystrobin (Heritage), chlorothalonil (Daconil), copper, ferbam, mancozeb, or maneb.
Only two diseases are commonly troublesome on zinnias (Zinnia elegans), powdery mildew and Alternaria blight. Alternaria blight is the most common and conspicuous.
Symptoms and Diagnosis
Spotting of the foliage caused by the fungus, Alternaria zinniae, is the most conspicuous symptom of zinnia blight. Individual spots are at first circular in outline but rapidly become irregular. The spots may vary from 2 to 10 millimeters or more in diameter, are reddish brown, and have grayish-white centers on the upper leaf surface. Differentiation of margin and center is lacking on the lower surface. As the spots increase in size and number, they coalesce and the affected leaves become brown and dry.
Blossoms may be severely affected. Brown spots, 1 or 2 millimeters in diameter, with grayish-white centers sometimes appear on the petal tissues of the ray flowers. Affected plants soon darken and wither, causing blossoms to become unsightly.
Numerous, small, reddish spots, sometimes with grayish-white centers, may be seen on stem internodes. Such spots usually are superficial. Spots that develop at nodes, however, usually do not remain superficial. Instead, they grow or coalesce into larger lesions that frequently girdle the stem causing the upper portions of the affected stem to die back to the node. Dark brown to black cankers with sunken centers are also common at the base of the stem of diseased plants. Affected plants often wilt completely, even when the basal cankers do not encircle the stem.
The outer tissues of affected roots may become dark gray, rot completely, and slough off, resulting in wilting and death of the plant. Damping-off of seedlings also may occur.
Life Cycle
The fungus survives on seeds and in the soil associated with host debris. Midsummer and early fall are normal times of outbreak.
Integrated Pest Management Strategies
1. Sanitation. Clean up debris; bury or burn if possible. Fungus may remain associated with plant material for 2 years.
2. Rotation. Use a long crop rotation of three years if growing commercially. A two-year rotation schedule is satisfactory for home garden and small isolated areas where disease spread can be limited.
3. Resistant varieties. Use resistant varieties of Zinnia elegans when possible. But be warned, no cultivars to date have been found to be totally resistant to Alternaria blight.
4. Propagation. Seeds may be infected with the fungus. Before planting, treat the seeds by placing them in hot water at 125 degrees F for 30 minutes. Then cool and dry. Older seeds can be injured by this treatment.
5. Watering. Do not use overhead irrigation. Water at the base of plants.
6. Fungicides. Use protectant fungicides. Spray seedlings and young plants with azoxystrobin (Heritage), chlorothalonil (Daconil), copper, ferbam, mancozeb, or maneb.
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成长记
Ueca
2017年09月16日
It's now been a full year since this plant first appeared as a speck on a fallen leaf from my local department store.
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文章
Dummer. ゛☀
2017年09月15日
Horse chestnut leaf miner (Cameraria ohridella) is an exotic insect pest which lives in horse chestnut trees. It was first reported in the UK in 2002, in the London Borough of Wimbledon, and has since spread north, south and west to most of England and parts of Wales, and there has been one confirmed sighting in Scotland.
Its larvae (caterpillars) mine within the leaves, and at high population densities they can destroy most of the leaf tissues. Although it can cause severe damage to horse chestnut leaves on an annual basis, and discolouration and defoliation before normal autumn leaf-fall, on its own the pest does not significantly impair trees' health, and they will usually flush normally the following spring.
However, it is possible that differences in climate, or interactions with other pests and diseases, might lead to greater impact in the UK. Consequently, the effects of the moth and its interaction with other pests and diseases, especially bleeding canker of horse chestnut, is being studied through the long-term monitoring of more than 300 chestnut trees at several sites in southern England. These trees are assessed twice each year for infestation, disease crown condition, growth and signs of dieback.
Origins
Horse chestnut leaf miner was first observed in Macedonia, in northern Greece, in 1985, and was described as a new species in 1986. In 1989, it appeared unexpectedly in Austria, and since then it has spread throughout central and eastern Europe. It was first found in Great Britain in 2002 in the London Borough of Wimbledon.
Spread
Dispersal of the moth from infested areas occurs on a broad front through adult flight, assisted by the wind, and through the passive transport of adult moths or infested leaves in or on vehicles. Transportation by vehicles appears to be responsible for the sudden appearance of the moth in towns and cities a long way from known areas of infestation.
Distribution
The map shows areas where confirmed sightings of horse chestnut leaf miner had been reported up to 2014.
Forest Research scientists are conducting a long-term study to determine whether there are any interactions of Horse chestnut leaf miner and the bacterum P. syringae pv. aesculi , which causes bleeding canker of horse chestnut, including whether one influences the extent of the other, and how they affect the health of affected trees. A paper reporting the results of the first 10 years of the study was published in the journal Agricultural and Forest Entomology.
Treatment
Damage can be reduced by removing fallen leaves during the autumn and winter and either composting them thoroughly, to destroy the over-wintering pupae, or if the leaves are collected into smaller heaps, by covering them with a layer of soil or other plant material to prevent adult emergence the following spring.
Its larvae (caterpillars) mine within the leaves, and at high population densities they can destroy most of the leaf tissues. Although it can cause severe damage to horse chestnut leaves on an annual basis, and discolouration and defoliation before normal autumn leaf-fall, on its own the pest does not significantly impair trees' health, and they will usually flush normally the following spring.
However, it is possible that differences in climate, or interactions with other pests and diseases, might lead to greater impact in the UK. Consequently, the effects of the moth and its interaction with other pests and diseases, especially bleeding canker of horse chestnut, is being studied through the long-term monitoring of more than 300 chestnut trees at several sites in southern England. These trees are assessed twice each year for infestation, disease crown condition, growth and signs of dieback.
Origins
Horse chestnut leaf miner was first observed in Macedonia, in northern Greece, in 1985, and was described as a new species in 1986. In 1989, it appeared unexpectedly in Austria, and since then it has spread throughout central and eastern Europe. It was first found in Great Britain in 2002 in the London Borough of Wimbledon.
Spread
Dispersal of the moth from infested areas occurs on a broad front through adult flight, assisted by the wind, and through the passive transport of adult moths or infested leaves in or on vehicles. Transportation by vehicles appears to be responsible for the sudden appearance of the moth in towns and cities a long way from known areas of infestation.
Distribution
The map shows areas where confirmed sightings of horse chestnut leaf miner had been reported up to 2014.
Forest Research scientists are conducting a long-term study to determine whether there are any interactions of Horse chestnut leaf miner and the bacterum P. syringae pv. aesculi , which causes bleeding canker of horse chestnut, including whether one influences the extent of the other, and how they affect the health of affected trees. A paper reporting the results of the first 10 years of the study was published in the journal Agricultural and Forest Entomology.
Treatment
Damage can be reduced by removing fallen leaves during the autumn and winter and either composting them thoroughly, to destroy the over-wintering pupae, or if the leaves are collected into smaller heaps, by covering them with a layer of soil or other plant material to prevent adult emergence the following spring.
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文章
Dummer. ゛☀
2017年09月15日
Leaves that become skeletonised or transparent with just their veins remaining tend to be the work of sawflies, which eat through the tissue of the leaf until it has almost completely disappeared. The larvae can often be seen around the edges of the leaves and most curl up into an S-shape when disturbed. Larvae will also bore into developing fruits causing them to become scarred and exude sticky liquid.
Plants affected
Sawflies affect a number of different plants but different types tend to affect different crops. Some of the most common are the apple sawfly (hoplocampa testudinae), the common gooseberry sawfly (Nematus ribesii), the turnip sawfly (Athalia rosae) the pear and cherry 'slugworm' (Caliroa cerasi), the rose slug sawfly (Endelomyia aethiops), also known as the rose 'skeletoniser'.
About Sawflies
Adult sawflies are usually inconspicuous flying insects with two pairs of wings and often dark coloured bodies and legs. They resemble flying ants but have no 'waist' between thorax and abdomen.
They're often seen flying on warm sunny days in spring at blossom time when they usually feed on pollen and nectar.
The adults live for about two weeks, during which time they mate before the females start laying eggs into plant tissue.
Eggs are inserted into cuts on the leaf surfaces that the female makes with her saw-like ovipositor.
Eggs hatch into larvae that resemble moth caterpillars, although they have more pairs of 'pro-legs' on their abdominal segments.
The larvae usually feed in groups on leaves and fruit of plants.
When disturbed, the larvae of most sawfly species adopt an S-shaped pose, often raising their rear ends and waving them about.
At least 400 different species of sawfly have been recorded on plants in Britain.
Larvae usually feed for about four to five weeks before pupating in the soil.
Infestations of sawfly larvae often defoliate plants although infestations are usually localised and rarely devastating.
Two or three adult generations may develop during the growing season with the third generation overwintering as pupae that emerge in the spring
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Sawflies
Pyrethrum
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Inspect bushes every week from April/May onwards for the signs of sawfly infestation then search for the larvae and remove by hand.
Tell-tale signs include transparent patches on leaves where young larvae are feeding; seeping sap, where the insects have damaged plant tissue as they lay eggs; areas of defoliation or skeletonised leaves.
Position susceptible plants in an open position where birds can easily feed on the larvae.
Prevention
Select varieties that are reported as less susceptible to attack, particularly roses and apples.
Plants affected
Sawflies affect a number of different plants but different types tend to affect different crops. Some of the most common are the apple sawfly (hoplocampa testudinae), the common gooseberry sawfly (Nematus ribesii), the turnip sawfly (Athalia rosae) the pear and cherry 'slugworm' (Caliroa cerasi), the rose slug sawfly (Endelomyia aethiops), also known as the rose 'skeletoniser'.
About Sawflies
Adult sawflies are usually inconspicuous flying insects with two pairs of wings and often dark coloured bodies and legs. They resemble flying ants but have no 'waist' between thorax and abdomen.
They're often seen flying on warm sunny days in spring at blossom time when they usually feed on pollen and nectar.
The adults live for about two weeks, during which time they mate before the females start laying eggs into plant tissue.
Eggs are inserted into cuts on the leaf surfaces that the female makes with her saw-like ovipositor.
Eggs hatch into larvae that resemble moth caterpillars, although they have more pairs of 'pro-legs' on their abdominal segments.
The larvae usually feed in groups on leaves and fruit of plants.
When disturbed, the larvae of most sawfly species adopt an S-shaped pose, often raising their rear ends and waving them about.
At least 400 different species of sawfly have been recorded on plants in Britain.
Larvae usually feed for about four to five weeks before pupating in the soil.
Infestations of sawfly larvae often defoliate plants although infestations are usually localised and rarely devastating.
Two or three adult generations may develop during the growing season with the third generation overwintering as pupae that emerge in the spring
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Sawflies
Pyrethrum
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Inspect bushes every week from April/May onwards for the signs of sawfly infestation then search for the larvae and remove by hand.
Tell-tale signs include transparent patches on leaves where young larvae are feeding; seeping sap, where the insects have damaged plant tissue as they lay eggs; areas of defoliation or skeletonised leaves.
Position susceptible plants in an open position where birds can easily feed on the larvae.
Prevention
Select varieties that are reported as less susceptible to attack, particularly roses and apples.
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文章
Dummer. ゛☀
2017年09月15日
If the shoots tips of rosemary and lavender are turning brown and dying back it could be the sign of an infestation of rosemary leaf beetle. These small beetles feed on the new shoot tips causing them to die back. They're easy to spot because they have metallic green and purple stripes across their backs. Their larvae, which are slug-like and pale grey in colour with a dark stripe down the side, also cause damage by feeding on the shoots as they grow.
Plants affected
Rosemary leaf beetles only feed on a small number of plant species which includes rosemary, lavender, sage and thyme.
About Rosemary leaf beetle
These attractive leaf beetles are an invasive species that first appeared in the UK in 1994.
Since their introduction, they've been spreading steadily throughout the southern counties of England.
The adult beetles are around 1cm long with metallic green and purple stripes down their wing cases.
They're usually found in groups on stems, or feeding on the new growth of plants.
The larvae are small slug-like grubs which are usually found on the underside of leaves. They are light grey with horizontal dark stripes along their body.
Adult beetles are usually first seen in late spring, although they remain largely stationary on plants until later in the year.
In late summer they'll begin to mate and lay eggs.
Eggs are usually laid on the underside of leaves and are around 2mm in length.
Larvae will hatch in about ten day's time and feed for a few weeks before dropping down to pupate below the soil surface.
Adults may continue to mate during warmer winter periods, although this is rare.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Rosemary leaf beetle
Pyrethrum
Natural fatty acids
Surfactant-based products
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regular observation in late spring each year is essential to prevent infestations establishing.
Removing adults and larvae by hand will help to reduce numbers. Shaking infested bushes over an old towel or sheet will enable large infestations to be collected and removed.
Netting and fleeces can be used to stop adults moving between plants.
There are currently no natural enemies commercially available to control rosemary leaf beetle.
Prevention
Check plants on a weekly basis for signs of infestation and deal with them as soon as they appear.
Encourage insectivorous birds by hanging feeders in the winter and provide nesting boxes in the spring.
Plants affected
Rosemary leaf beetles only feed on a small number of plant species which includes rosemary, lavender, sage and thyme.
About Rosemary leaf beetle
These attractive leaf beetles are an invasive species that first appeared in the UK in 1994.
Since their introduction, they've been spreading steadily throughout the southern counties of England.
The adult beetles are around 1cm long with metallic green and purple stripes down their wing cases.
They're usually found in groups on stems, or feeding on the new growth of plants.
The larvae are small slug-like grubs which are usually found on the underside of leaves. They are light grey with horizontal dark stripes along their body.
Adult beetles are usually first seen in late spring, although they remain largely stationary on plants until later in the year.
In late summer they'll begin to mate and lay eggs.
Eggs are usually laid on the underside of leaves and are around 2mm in length.
Larvae will hatch in about ten day's time and feed for a few weeks before dropping down to pupate below the soil surface.
Adults may continue to mate during warmer winter periods, although this is rare.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Rosemary leaf beetle
Pyrethrum
Natural fatty acids
Surfactant-based products
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regular observation in late spring each year is essential to prevent infestations establishing.
Removing adults and larvae by hand will help to reduce numbers. Shaking infested bushes over an old towel or sheet will enable large infestations to be collected and removed.
Netting and fleeces can be used to stop adults moving between plants.
There are currently no natural enemies commercially available to control rosemary leaf beetle.
Prevention
Check plants on a weekly basis for signs of infestation and deal with them as soon as they appear.
Encourage insectivorous birds by hanging feeders in the winter and provide nesting boxes in the spring.
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文章
Dummer. ゛☀
2017年09月15日
Mottled, yellowing leaves with brown speckles are signs that these tiny pests have been feeding on plant leaf cells. Sometimes you can also see the fine silk webbing spun by adult spider mites, which they use to travel from one plant to another.
Plants affected
Spider mites feed on at least 200 different plants, including many common flowers, fruits and vegetables.
About Red spider mite
Spider mites are arachnids and are related to all spider species.
These tiny, highly destructive pests are common in greenhouses and on house plants and can also be found on outdoor plants during the warmer summer months.
Spider mites can feed on at least 200 different plants, including many common flowers, fruits and vegetables.
They feed on the content of plant leaf cells by piercing them with their mouthparts. This results in a fine brown speckling effect on leaves where the cells have died.
Adult mites also spin a fine silk webbing over leaf surfaces. With heavy infestations this can cover most of the plant.
When active, the spider mites are light green with two dark spots on their back, but during their inactive periods they become dark orange or red.
Spider mites emerge from hibernation during March and April and begin laying their minute, spherical eggs on suitable host plants.
Adult females can lay up to a hundred eggs during their lifetime.
Juveniles will hatch a few days later and begin feeding. They start life with six legs, but develop eight as they mature.
The webbing provides a protective shield for the spider mite colony against predators and adverse environmental conditions. It also provides a means of spreading the colony to other areas of the plant.
As autumn approaches, females stop laying eggs and begin to seek out places away from the plant to overwinter. They'll usually choose places, such as cracks in walls, fences and old plant material.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Red spider mite
Natural fatty acids
Surfactant-based products
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Inspect plants every week and deal with the first signs of mite infestation immediately.
Where possible, remove infested leaves, buds and stems because this will initially reduce numbers.
Spider mites prefer dry environments, so spraying the infested areas of a plant with water and damping the greenhouse floor areas will raise the humidity and hopefully slow the infestation rate.
The predatory mite Phytosieulus persimilis feeds on Red spider mite, and reproduces much faster than its prey at temperatures above 18C (64F). This can be released on to infected areas and should quickly control infestations.
Prevention
Mites overwinter in cracks and crevices in greenhouses, as well as in any plant material left behind. So it's essential to clear away all debris once the growing season is over and thoroughly disinfect the greenhouse to keep pest numbers to a minimum.
Keep the greenhouse atmosphere quite humid and damp by wetting the floor regularly. Mites hate damp conditions and this will help to discourage them from making a home here.
Plants affected
Spider mites feed on at least 200 different plants, including many common flowers, fruits and vegetables.
About Red spider mite
Spider mites are arachnids and are related to all spider species.
These tiny, highly destructive pests are common in greenhouses and on house plants and can also be found on outdoor plants during the warmer summer months.
Spider mites can feed on at least 200 different plants, including many common flowers, fruits and vegetables.
They feed on the content of plant leaf cells by piercing them with their mouthparts. This results in a fine brown speckling effect on leaves where the cells have died.
Adult mites also spin a fine silk webbing over leaf surfaces. With heavy infestations this can cover most of the plant.
When active, the spider mites are light green with two dark spots on their back, but during their inactive periods they become dark orange or red.
Spider mites emerge from hibernation during March and April and begin laying their minute, spherical eggs on suitable host plants.
Adult females can lay up to a hundred eggs during their lifetime.
Juveniles will hatch a few days later and begin feeding. They start life with six legs, but develop eight as they mature.
The webbing provides a protective shield for the spider mite colony against predators and adverse environmental conditions. It also provides a means of spreading the colony to other areas of the plant.
As autumn approaches, females stop laying eggs and begin to seek out places away from the plant to overwinter. They'll usually choose places, such as cracks in walls, fences and old plant material.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Red spider mite
Natural fatty acids
Surfactant-based products
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Inspect plants every week and deal with the first signs of mite infestation immediately.
Where possible, remove infested leaves, buds and stems because this will initially reduce numbers.
Spider mites prefer dry environments, so spraying the infested areas of a plant with water and damping the greenhouse floor areas will raise the humidity and hopefully slow the infestation rate.
The predatory mite Phytosieulus persimilis feeds on Red spider mite, and reproduces much faster than its prey at temperatures above 18C (64F). This can be released on to infected areas and should quickly control infestations.
Prevention
Mites overwinter in cracks and crevices in greenhouses, as well as in any plant material left behind. So it's essential to clear away all debris once the growing season is over and thoroughly disinfect the greenhouse to keep pest numbers to a minimum.
Keep the greenhouse atmosphere quite humid and damp by wetting the floor regularly. Mites hate damp conditions and this will help to discourage them from making a home here.
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Dummer. ゛☀
2017年09月15日
Holes in the leaves giving a lace-work look as caterpillars feed on the soft tissue between the veins. Once the caterpillars are feeding leaf discolouration and rapid defoliation often results as they decimate the crop. Check for adult moths, caterpillars and their frass, or droppings.
Plants affected
The whole cabbage family, for example cauliflowers, turnips, kale, rape, Brussels sprouts, broccoli, watercress, but the main host plants are cabbages. Sometimes mustard plants and ornamental cultivated plants can be infested, such as sweet alyssum, wallflower, candytuft and stocks.
About Diamondback moth
Adult moths are nocturnal, 8mm in length, grey/brown, long and thin in shape with diamond markings on their backs.
They often migrate to this country in large numbers from mainland Europe.
The green caterpillars grow to 12mm in length and are thicker in the middle of their bodies.
This moth goes through four larval stages before pupating and becoming an adult, over a 15-30 day period.
Plant damage is only caused by the caterpillars, with the last stage causing the worst damage.
Plants are often stripped bare by heavy infestations.
Caterpillars pupate in loosely spun silken cocoons attached to the undersides of leaves.
It is the pupal stages that overwinter, although up to six generations can occur each year.
Adult moths emerge in May to mate and lay shiny, yellow eggs. Eggs are 1mm in width and are laid on leaves singly or in pairs.
If threatened, caterpillars drop off the leaves and hang by a thread.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Diamondback moth
Pyrethroids and Pyrethrin
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Encourage natural predators and parasites.
Regular observation of crops to check for damage or infestation.
Crop containment, for example, grow in polytunnels, greenhouses or under fleece.
Companion planting with marigolds or onions.
Avoid sowing crop at peak breeding times.
Water foliage regularly as larvae can be easily drowned.
Prevention
Thoroughly check, and remove infested plants.
Use sticky traps to monitor the first appearance of adult moths.
Plants affected
The whole cabbage family, for example cauliflowers, turnips, kale, rape, Brussels sprouts, broccoli, watercress, but the main host plants are cabbages. Sometimes mustard plants and ornamental cultivated plants can be infested, such as sweet alyssum, wallflower, candytuft and stocks.
About Diamondback moth
Adult moths are nocturnal, 8mm in length, grey/brown, long and thin in shape with diamond markings on their backs.
They often migrate to this country in large numbers from mainland Europe.
The green caterpillars grow to 12mm in length and are thicker in the middle of their bodies.
This moth goes through four larval stages before pupating and becoming an adult, over a 15-30 day period.
Plant damage is only caused by the caterpillars, with the last stage causing the worst damage.
Plants are often stripped bare by heavy infestations.
Caterpillars pupate in loosely spun silken cocoons attached to the undersides of leaves.
It is the pupal stages that overwinter, although up to six generations can occur each year.
Adult moths emerge in May to mate and lay shiny, yellow eggs. Eggs are 1mm in width and are laid on leaves singly or in pairs.
If threatened, caterpillars drop off the leaves and hang by a thread.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Diamondback moth
Pyrethroids and Pyrethrin
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Encourage natural predators and parasites.
Regular observation of crops to check for damage or infestation.
Crop containment, for example, grow in polytunnels, greenhouses or under fleece.
Companion planting with marigolds or onions.
Avoid sowing crop at peak breeding times.
Water foliage regularly as larvae can be easily drowned.
Prevention
Thoroughly check, and remove infested plants.
Use sticky traps to monitor the first appearance of adult moths.
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文章
Dummer. ゛☀
2017年09月15日
Distorted, yellowing or slowed growth on plants can often be a sign of scale insects. These look like tiny brown or orange blobs and can often be found on the undersides of the leaves near the veins, on the stems or in the leaf joints. They produce sticky honeydew as they feed which can cause the foliage on infested plants to become sticky and covered with dark sooty mould.
Plants affected
Scales are usually pests of ornamental plants and can be especially troublesome in greenhouses. Over 300 species of ornamental plants are known hosts.
About Scale insects
Scale insects are small sap-sucking insects, so called because they produce an umbrella-like waxy coating or 'scale' over their soft bodies.
They're often difficult to detect on plants, although leaf yellowing or sticky honeydew deposits can be the first signs of infestation.
Scale insects may appear as small, flattened white, yellow or brown 'discs' or 'blobs', on stems or on the underside of leaves near the veins.
Scale insects are divided into two families - soft scale (Coccidae) and hard scale (Diaspididae).
Soft scales can breed all year round on protected crops and produce large amounts of sugary honeydew when they feed on the plant's sap. This honeydew attracts sooty moulds that grow on the leaves.
Hard scales lay eggs under their scales which hatch into nymphs or 'crawlers' after the female dies in early summer.
The nymphs can move short distances on a plant, but disperse long distances on the wind or on animals.
Hard scale don't produce large amounts of honeydew.
Female scale insect nymphs become immobile once they find a suitable feeding site and become adults.
Males are rarely seen but are often winged and midge-like in appearance.
The 'scale' produced by these insects can remain on a plant for a long time after they're dead.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Scale insects
Pyrethrum
Natural fatty acids
Rape seed oil
Tar oil wash (for use on deciduous trees and roses in December)
Thiacloprid (for use with outdoor fruit crops)
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Check bought plants thoroughly. If an infestation is in the early stages, the scales can be cleaned off using a brush and water, or just a thumbnail.
Biological control is available in the form of a tiny wasp which parasitises soft scales, Metaphycus helvolus. This can be purchased for release into the greenhouse but requires good light and temperatures of at least 22°C (72°F) to be effective.
The small predatory ladybird Chilocorus nigritus can also be purchased, that feeds on hard scale species. Lacewing larvae also control scale.
Prevention
Check plants regularly for signs of scale infestation and deal with them as soon as they appear.
Keep the environment clear of weeds because these often harbour the pest.
Monitor plants for signs of scale, such as leaf drop, honeydew or sooty mould.
Look out for ants running up and down the plants, 'milking' the honeydew.
Avoid using broad spectrum insecticides which will kill beneficial insects as well as scale.
Destroy any leaves that have been removed from an infested plant because these can harbour many mobile juvenile scales.
Plants affected
Scales are usually pests of ornamental plants and can be especially troublesome in greenhouses. Over 300 species of ornamental plants are known hosts.
About Scale insects
Scale insects are small sap-sucking insects, so called because they produce an umbrella-like waxy coating or 'scale' over their soft bodies.
They're often difficult to detect on plants, although leaf yellowing or sticky honeydew deposits can be the first signs of infestation.
Scale insects may appear as small, flattened white, yellow or brown 'discs' or 'blobs', on stems or on the underside of leaves near the veins.
Scale insects are divided into two families - soft scale (Coccidae) and hard scale (Diaspididae).
Soft scales can breed all year round on protected crops and produce large amounts of sugary honeydew when they feed on the plant's sap. This honeydew attracts sooty moulds that grow on the leaves.
Hard scales lay eggs under their scales which hatch into nymphs or 'crawlers' after the female dies in early summer.
The nymphs can move short distances on a plant, but disperse long distances on the wind or on animals.
Hard scale don't produce large amounts of honeydew.
Female scale insect nymphs become immobile once they find a suitable feeding site and become adults.
Males are rarely seen but are often winged and midge-like in appearance.
The 'scale' produced by these insects can remain on a plant for a long time after they're dead.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Scale insects
Pyrethrum
Natural fatty acids
Rape seed oil
Tar oil wash (for use on deciduous trees and roses in December)
Thiacloprid (for use with outdoor fruit crops)
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Check bought plants thoroughly. If an infestation is in the early stages, the scales can be cleaned off using a brush and water, or just a thumbnail.
Biological control is available in the form of a tiny wasp which parasitises soft scales, Metaphycus helvolus. This can be purchased for release into the greenhouse but requires good light and temperatures of at least 22°C (72°F) to be effective.
The small predatory ladybird Chilocorus nigritus can also be purchased, that feeds on hard scale species. Lacewing larvae also control scale.
Prevention
Check plants regularly for signs of scale infestation and deal with them as soon as they appear.
Keep the environment clear of weeds because these often harbour the pest.
Monitor plants for signs of scale, such as leaf drop, honeydew or sooty mould.
Look out for ants running up and down the plants, 'milking' the honeydew.
Avoid using broad spectrum insecticides which will kill beneficial insects as well as scale.
Destroy any leaves that have been removed from an infested plant because these can harbour many mobile juvenile scales.
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文章
Dummer. ゛☀
2017年09月15日
Carrot flies, also known as carrot root flies, infect their host plant's roots causing widespread damage to crops. The damage is caused as the fly larvae feed. Signs to check for are leaf discolouration, and holes or tunnels in the carrot. The holes often turn a rusty colour due to a fungal disease called carrot or parsnip canker which commonly infects the damaged area.
Plants affected
Carrot flies are a major pest of the whole carrot family. The main host plant is carrots but they also attack celery, celeriac, parsnips and parsley.
About Carrot fly
Adult carrot flies are part of a group known as stilt-legged-flies. They have long orange legs, a black body and a red/brown head. They're about 4-5mm long and poor fliers.
The larvae of the carrot fly are the major cause of plant damage.
They are maggot-like in appearance, growing to about 10mm in length and are creamy yellow in colour.
Carrot fly pupae are brownish yellow in colour and are found in the soil.
Carrot fly larvae often cause widespread damage since they move through the soil feeding on different roots.
Adult carrot flies overwinter below ground and emerge in the spring to mate.
The first generation of eggs are laid into the soil surrounding the host plants.
A second generation emerges in July and August. It's this generation that overwinters in the soil.
Occasionally there can be three generations a year if environmental conditions are favourable.
If carrot or parsnip canker spores are present within the soil, they can often infect the areas where carrot root fly larvae have been feeding. This causes a rust colouration of the affected areas.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Carrot fly
There are no approved insecticides currently available to amateur gardeners.
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regular checks for damage or infestation.
Crop containment, for example, covering plants with a fleece barrier.
Choose growing sites that are fairly open and exposed.
Remove damaged plants to reduce the smell of carrot which attracts the flies.
Companion plant with strong smelling plants to mask the carrot smell, such as onions.
Avoid sowing susceptible plant seed during the early spring and late summer when carrot flies will be laying eggs.
Thin seedlings in the evening when adult flies are less active and then destroy all thinned plants.
Firm the soil around the plants after thinning as this deters the flies from laying eggs.
Prevention
Check the crop regularly for signs of infestation and promptly remove any affected plants.
Grow less susceptible varieties, such as 'Fly Away' and 'Resistafly', which are low in phenolic acid.
During the winter, thoroughly fork through the soil where susceptible plants will be grown. This should expose overwintering carrot flies to frosts and predators.
Plants affected
Carrot flies are a major pest of the whole carrot family. The main host plant is carrots but they also attack celery, celeriac, parsnips and parsley.
About Carrot fly
Adult carrot flies are part of a group known as stilt-legged-flies. They have long orange legs, a black body and a red/brown head. They're about 4-5mm long and poor fliers.
The larvae of the carrot fly are the major cause of plant damage.
They are maggot-like in appearance, growing to about 10mm in length and are creamy yellow in colour.
Carrot fly pupae are brownish yellow in colour and are found in the soil.
Carrot fly larvae often cause widespread damage since they move through the soil feeding on different roots.
Adult carrot flies overwinter below ground and emerge in the spring to mate.
The first generation of eggs are laid into the soil surrounding the host plants.
A second generation emerges in July and August. It's this generation that overwinters in the soil.
Occasionally there can be three generations a year if environmental conditions are favourable.
If carrot or parsnip canker spores are present within the soil, they can often infect the areas where carrot root fly larvae have been feeding. This causes a rust colouration of the affected areas.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Carrot fly
There are no approved insecticides currently available to amateur gardeners.
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regular checks for damage or infestation.
Crop containment, for example, covering plants with a fleece barrier.
Choose growing sites that are fairly open and exposed.
Remove damaged plants to reduce the smell of carrot which attracts the flies.
Companion plant with strong smelling plants to mask the carrot smell, such as onions.
Avoid sowing susceptible plant seed during the early spring and late summer when carrot flies will be laying eggs.
Thin seedlings in the evening when adult flies are less active and then destroy all thinned plants.
Firm the soil around the plants after thinning as this deters the flies from laying eggs.
Prevention
Check the crop regularly for signs of infestation and promptly remove any affected plants.
Grow less susceptible varieties, such as 'Fly Away' and 'Resistafly', which are low in phenolic acid.
During the winter, thoroughly fork through the soil where susceptible plants will be grown. This should expose overwintering carrot flies to frosts and predators.
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文章
Dummer. ゛☀
2017年09月15日
Distorted and misshapen leaves, flowers, buds and fruit growth. The leaf tissue around affected areas may become brown and eventually die.
Plants affected
Many different garden plants are affected including fruits, vegetables, ornamentals, trees and weeds.
About Capsid bugs
Capsid bugs feed on plant sap and in doing so cause deformation of plant material.
There are many different species of capsid bugs in the UK.
Capsids are also known as mirid bugs.
Some species of capsid also feed on other small insects.
Adults vary in colour from green to red/ brown, around 6mm in length, and have a long, slender feeding tube.
Young are similar in shape and colour, but smaller and wingless.
When disturbed they fall down onto the soil as a defence.
When feeding they inject saliva which is toxic to plants.
There can be one or two generations per year depending on the species.
Eggs are laid into cracks in tree bark, woody stems, and at the base of hedges. They hatch in late spring.
Depending on species, over-wintering takes place as eggs or as adults in plant debris.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Capsid bugs
Pyrethrins
Pyrethroids
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regularly inspect plants in spring.
Remove and destroy adults by hand.
Winter wash trees to destroy eggs.
Prevention
Keep areas around plants free from plant debris.
Remove weeds around plants.
Plants affected
Many different garden plants are affected including fruits, vegetables, ornamentals, trees and weeds.
About Capsid bugs
Capsid bugs feed on plant sap and in doing so cause deformation of plant material.
There are many different species of capsid bugs in the UK.
Capsids are also known as mirid bugs.
Some species of capsid also feed on other small insects.
Adults vary in colour from green to red/ brown, around 6mm in length, and have a long, slender feeding tube.
Young are similar in shape and colour, but smaller and wingless.
When disturbed they fall down onto the soil as a defence.
When feeding they inject saliva which is toxic to plants.
There can be one or two generations per year depending on the species.
Eggs are laid into cracks in tree bark, woody stems, and at the base of hedges. They hatch in late spring.
Depending on species, over-wintering takes place as eggs or as adults in plant debris.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Capsid bugs
Pyrethrins
Pyrethroids
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regularly inspect plants in spring.
Remove and destroy adults by hand.
Winter wash trees to destroy eggs.
Prevention
Keep areas around plants free from plant debris.
Remove weeds around plants.
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文章
Dummer. ゛☀
2017年09月15日
Damage from leaf miner larvae — the tunnels or mines that scroll across leaves — is easy to spot. The leafminer parasite (Diglyphus isaea) is a small, black, non-stinging wasp that searches out leaf miners on which to lay its egg. The wasp kills the leaf miner as it lays its egg, and the emerging larvae use the dead miner as food. The adult parasite exits the tunnel sometime later and will then go on to lay 200 – 300 eggs during its nearly month-long life. While destructive leaf miners often survive pesticide treatments because they are protected inside the tunnels, they cannot escape the parasite, which raps its antennae on the mine to locate the miner. Leaves with short or dead-ended mines often indicate the presence of D. isaea.
Shop our large selection of biological controls, including leaf-miner parasites, at Planet Natural. One bottle — 500 adults — treats up to 20,000 square feet and costs $234.95 with UPS Express shipping included!
HOW TO RELEASE:
Make introductions when leaf miner infection increases.
Apply in the morning or evening between the leaves on plants.
Each 100 ml bottle (500 adults) will treat 5,000-20,000 square feet, depending on pest levels.
Shop our large selection of biological controls, including leaf-miner parasites, at Planet Natural. One bottle — 500 adults — treats up to 20,000 square feet and costs $234.95 with UPS Express shipping included!
HOW TO RELEASE:
Make introductions when leaf miner infection increases.
Apply in the morning or evening between the leaves on plants.
Each 100 ml bottle (500 adults) will treat 5,000-20,000 square feet, depending on pest levels.
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文章
Dummer. ゛☀
2017年09月15日
Pathogen-caused leaf spot diseases, particularly those of stone fruit trees and such vegetables as tomatoes, peppers and lettuce are of two types, those caused by bacteria and those caused by fungus. Leaf spotting of either kind is generally similar in appearance and effect. Prevention and treatment of both kinds often involve the same practices.
Symptoms
Infected plants have brown or black water-soaked spots on the foliage, sometimes with a yellow halo, usually uniform in size. The spots enlarge and will run together under wet conditions. Under dry conditions the spots have a speckled appearance. As spots become more numerous, entire leaves may yellow, wither and drop. Members of the Prunus family (stone fruits, including cherry, plum, almond, apricot and peach) are particularly susceptible to bacterial leaf spot. The fruit may appear spotted or have sunken brown areas. Bacterial leaf spot will also attack tomato and pepper crops in vegetable gardens.
Fungal leaf spot attacks lettuce and can also occur on brassicas and other vegetables including such as cabbage, cauliflower, Chinese cabbage, broccoli, Brussels sprouts, kohlrabi, kale, turnip and rutabaga. For more on vegetables susceptible to bacterial and fungal leaf spot, go here.
Bacterial leaf spot will also infect some annual and perennial flowering plants including geraniums, zinnias, purple cone flowers and black-eyed Susan. Fungal leaf spot will infect aspen and poplar trees. Leaf spot will also cause problems for strawberry plants.
Both types of leaf spot are most active when there is plenty of moisture and warm temperatures. During the summer months, especially if plants are watered by overhead sprinklers, sufficient moisture may be present for infection when the bacteria are splashed or blown on to leaves. Wind and rain transmit the bacteria to plants.
This disease overwinters in the soil around infected plants as well as on garden debris and seeds. It will also remain in the twig cankers, leaves, stems and fruit of infected trees.
Control
When selecting fruit trees, choose resistant varieties if possible.
Keep the soil under the tree clean and rake up fallen fruit.
Use a thick layer of mulch to cover the soil after you have raked and cleaned it well. Mulch will reduce weeds and prevent the disease pathogen from splashing back up onto the leaves.
Prune or stake plants to improve air circulation. Make sure to disinfect your pruning equipment (one part bleach to 4 parts water) after each cut.
Leaf spot among vegetables is most often introduced through infected seed or transplants. Make sure your seeds and transplants are from leaf spot-free stock.
There is no cure for plants infected with bacterial leaf spot. Preventive, organic measures include:
Spraying with a baking soda solution (a tablespoon of baking soda, 2 1/2 tablespoons of vegetable oil, a teaspoon of liquid soap, not detergent, to one gallon of water), or neem oil (do not use when pollinating insects including bees or other beneficial insects are present). Baking soda may burn some plant leaves. Spray only a few and then check for a reaction before applying applications every two weeks.
Apply sulfur sprays or copper-based fungicides weekly at first sign of disease to prevent its spread. These organic fungicides will not kill leaf spot, but prevent the spores from germinating.
Safely treat most fungal and bacterial diseases with SERENADE Garden. This broad spectrum bio-fungicide uses a patented strain of Bacillus subtilis that is registered for organic use. Best of all, SERENADE is completely non-toxic to honey bees and beneficial insects.
Containing copper and pyrethrins, Bonide® Garden Dust is a safe, one-step control for many insect attacks and fungal problems. For best results, cover both the tops and undersides of leaves with a thin uniform film or dust. Depending on foliage density, 10 oz will cover 625 sq ft. Repeat applications every 7-10 days, as needed.
Symptoms
Infected plants have brown or black water-soaked spots on the foliage, sometimes with a yellow halo, usually uniform in size. The spots enlarge and will run together under wet conditions. Under dry conditions the spots have a speckled appearance. As spots become more numerous, entire leaves may yellow, wither and drop. Members of the Prunus family (stone fruits, including cherry, plum, almond, apricot and peach) are particularly susceptible to bacterial leaf spot. The fruit may appear spotted or have sunken brown areas. Bacterial leaf spot will also attack tomato and pepper crops in vegetable gardens.
Fungal leaf spot attacks lettuce and can also occur on brassicas and other vegetables including such as cabbage, cauliflower, Chinese cabbage, broccoli, Brussels sprouts, kohlrabi, kale, turnip and rutabaga. For more on vegetables susceptible to bacterial and fungal leaf spot, go here.
Bacterial leaf spot will also infect some annual and perennial flowering plants including geraniums, zinnias, purple cone flowers and black-eyed Susan. Fungal leaf spot will infect aspen and poplar trees. Leaf spot will also cause problems for strawberry plants.
Both types of leaf spot are most active when there is plenty of moisture and warm temperatures. During the summer months, especially if plants are watered by overhead sprinklers, sufficient moisture may be present for infection when the bacteria are splashed or blown on to leaves. Wind and rain transmit the bacteria to plants.
This disease overwinters in the soil around infected plants as well as on garden debris and seeds. It will also remain in the twig cankers, leaves, stems and fruit of infected trees.
Control
When selecting fruit trees, choose resistant varieties if possible.
Keep the soil under the tree clean and rake up fallen fruit.
Use a thick layer of mulch to cover the soil after you have raked and cleaned it well. Mulch will reduce weeds and prevent the disease pathogen from splashing back up onto the leaves.
Prune or stake plants to improve air circulation. Make sure to disinfect your pruning equipment (one part bleach to 4 parts water) after each cut.
Leaf spot among vegetables is most often introduced through infected seed or transplants. Make sure your seeds and transplants are from leaf spot-free stock.
There is no cure for plants infected with bacterial leaf spot. Preventive, organic measures include:
Spraying with a baking soda solution (a tablespoon of baking soda, 2 1/2 tablespoons of vegetable oil, a teaspoon of liquid soap, not detergent, to one gallon of water), or neem oil (do not use when pollinating insects including bees or other beneficial insects are present). Baking soda may burn some plant leaves. Spray only a few and then check for a reaction before applying applications every two weeks.
Apply sulfur sprays or copper-based fungicides weekly at first sign of disease to prevent its spread. These organic fungicides will not kill leaf spot, but prevent the spores from germinating.
Safely treat most fungal and bacterial diseases with SERENADE Garden. This broad spectrum bio-fungicide uses a patented strain of Bacillus subtilis that is registered for organic use. Best of all, SERENADE is completely non-toxic to honey bees and beneficial insects.
Containing copper and pyrethrins, Bonide® Garden Dust is a safe, one-step control for many insect attacks and fungal problems. For best results, cover both the tops and undersides of leaves with a thin uniform film or dust. Depending on foliage density, 10 oz will cover 625 sq ft. Repeat applications every 7-10 days, as needed.
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文章
Dummer. ゛☀
2017年09月15日
A fungal disease that affects peaches and nectarines, leaf curl (Taphrina deformans) is one of the most common disease problems found in backyard orchards. Symptoms appears in spring as reddish areas on developing leaves. These areas become thick and puckered causing leaves to curl and distort. When severe, leaf curl can substantially reduce fruit production.
Disease fungi overwinter as spores (conidia) underneath bark, around buds and in other protected areas. Early in the growing season, during cool, wet spring weather, the spores infect new leaves as they emerge from the buds. Later, the fungus produces great numbers of new spores which are splashed or blown from tree to tree.
Leaf curl is most active at temperatures between 50-70˚F, but can occur at relatively low temperatures. In fact, cool weather is thought to extend the infection period because new leaves are growing slowly. Wet weather is necessary for infection.
Treatment
Select resistant varieties whenever possible.
Leaf curl can be controlled by applying sulfur or copper-based fungicides that are labeled for use on peaches and nectarines. Spray the entire tree after 90% of the leaves have dropped in the fall and again in the early spring, just before the buds open. For best results, trees should be sprayed to the point of runoff or until they start dripping.
Containing copper and pyrethrins, Bonide® Garden Dust is a safe, one-step control for many insect attacks and fungal problems. For best results, cover both the tops and undersides of leaves with a thin uniform film or dust. Depending on foliage density, 10 oz will cover 625 sq ft. Repeat applications every 7-10 days, as needed.
Keep the ground beneath the trees raked up and clean, especially during winter months.
Prune and destroy infected plant parts as they appear.
If disease problems are severe, maintain tree health and vigor by cutting back more fruit than normal, watering regularly (avoiding wetting the leaves if possible) and apply an organic fertilizers high in nitrogen.
Disease fungi overwinter as spores (conidia) underneath bark, around buds and in other protected areas. Early in the growing season, during cool, wet spring weather, the spores infect new leaves as they emerge from the buds. Later, the fungus produces great numbers of new spores which are splashed or blown from tree to tree.
Leaf curl is most active at temperatures between 50-70˚F, but can occur at relatively low temperatures. In fact, cool weather is thought to extend the infection period because new leaves are growing slowly. Wet weather is necessary for infection.
Treatment
Select resistant varieties whenever possible.
Leaf curl can be controlled by applying sulfur or copper-based fungicides that are labeled for use on peaches and nectarines. Spray the entire tree after 90% of the leaves have dropped in the fall and again in the early spring, just before the buds open. For best results, trees should be sprayed to the point of runoff or until they start dripping.
Containing copper and pyrethrins, Bonide® Garden Dust is a safe, one-step control for many insect attacks and fungal problems. For best results, cover both the tops and undersides of leaves with a thin uniform film or dust. Depending on foliage density, 10 oz will cover 625 sq ft. Repeat applications every 7-10 days, as needed.
Keep the ground beneath the trees raked up and clean, especially during winter months.
Prune and destroy infected plant parts as they appear.
If disease problems are severe, maintain tree health and vigor by cutting back more fruit than normal, watering regularly (avoiding wetting the leaves if possible) and apply an organic fertilizers high in nitrogen.
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