文章
Dummer. ゛☀
2017年09月15日
Viruses affect almost all types of plant from time to time and the symptoms are varied. Leaves may be yellowed or mottled. Spots, mosaics and other marks may also appear. Leaves can become deformed and twisted. Flowers may become streaked or develop a green colour.
Plants affected
Almost all plants can be affected by viruses and virus-like organisms with the notable exception of conifers.
About
Viruses are the simplest form of microscopic life. In fact some experts do not consider them true forms of life at all.
They cannot metabolise themselves, requiring a host to carry out any of their functions.
They can only reproduce inside a plant or animal host.
Viruses are usually carried from plant to plant by animals known as vectors. In plants, aphids are one of the most common vectors.
The same virus can cause very different symptoms in different plants.
Treatment
Prevention is the best place to start when dealing with viruses. Try to use certified virus-free seed potatoes and fruit trees.
Any plants showing signs of virus should be removed to prevent spread onto other plants.
Control of the organisms which transmit the virus is important to prevent its spread. Aphid control is particularly important.
Regular weeding will help by reducing other potential host plants in the area. Where there are weeds nearby which are in the same family as the plants at risk, this is especially important.
Keep the garden tidy and remove dead or dying plants promptly.
Plants affected
Almost all plants can be affected by viruses and virus-like organisms with the notable exception of conifers.
About
Viruses are the simplest form of microscopic life. In fact some experts do not consider them true forms of life at all.
They cannot metabolise themselves, requiring a host to carry out any of their functions.
They can only reproduce inside a plant or animal host.
Viruses are usually carried from plant to plant by animals known as vectors. In plants, aphids are one of the most common vectors.
The same virus can cause very different symptoms in different plants.
Treatment
Prevention is the best place to start when dealing with viruses. Try to use certified virus-free seed potatoes and fruit trees.
Any plants showing signs of virus should be removed to prevent spread onto other plants.
Control of the organisms which transmit the virus is important to prevent its spread. Aphid control is particularly important.
Regular weeding will help by reducing other potential host plants in the area. Where there are weeds nearby which are in the same family as the plants at risk, this is especially important.
Keep the garden tidy and remove dead or dying plants promptly.
0
0
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.
0
0
文章
Dummer. ゛☀
2017年09月15日
Rapid or gradual defoliation, where the lower leaves of the plant turn yellow and fall; wilting, drooping, spotted or stunted plants; or grey powdery mould round the stem, leaves or flowers. These symptoms can be indicative of other problems, but the presence of rotten roots as well would be a strong indication of water-logging.
Plants affected
Potentially all plants, but while drought damage occurs commonly in both outdoor and house-plants, over watering is relatively rare outdoors. It is probably the commonest cause of decline in house-plants, however, and much more serious than under watering.
About over watering
Plants vary hugely in the amount of water they need. It will depend very much on the type of plant, the season, the temperature and the climate.
Over watering is more damaging to the plant than under-watering. The rate of evaporation of water from the leaves, and the rate of transpiration through the stem and roots both affect the exchange of oxygen and carbon dioxide in the plant. The presence of too much water prevents the diffusion of these gases.
The commonest symptom is the yellowing of leaves.
Lack of oxygen to roots causes general stunting and encourages the development of rotting organisms.
Preventing further damage
For house plants check carefully their water requirements and water accordingly. Not many flourish when standing permanently in dishes of water.
Outdoors, check the soil condition: turning over heavy, loamy soils will aerate them and improve drainage.
Water slowly to prevent soaking some areas and leaving others dry.
Water in the morning when it is cool – during the day too much evaporation will occur and later in the evening humid conditions will cause fungal growth.
Always allow the saucers of pot plants to dry fully between waterings.
Make sure pots and plenty of drainage holes and fill bottom of pots with crocks, grit or gravel to prevent the holes becoming clogged.
Plants affected
Potentially all plants, but while drought damage occurs commonly in both outdoor and house-plants, over watering is relatively rare outdoors. It is probably the commonest cause of decline in house-plants, however, and much more serious than under watering.
About over watering
Plants vary hugely in the amount of water they need. It will depend very much on the type of plant, the season, the temperature and the climate.
Over watering is more damaging to the plant than under-watering. The rate of evaporation of water from the leaves, and the rate of transpiration through the stem and roots both affect the exchange of oxygen and carbon dioxide in the plant. The presence of too much water prevents the diffusion of these gases.
The commonest symptom is the yellowing of leaves.
Lack of oxygen to roots causes general stunting and encourages the development of rotting organisms.
Preventing further damage
For house plants check carefully their water requirements and water accordingly. Not many flourish when standing permanently in dishes of water.
Outdoors, check the soil condition: turning over heavy, loamy soils will aerate them and improve drainage.
Water slowly to prevent soaking some areas and leaving others dry.
Water in the morning when it is cool – during the day too much evaporation will occur and later in the evening humid conditions will cause fungal growth.
Always allow the saucers of pot plants to dry fully between waterings.
Make sure pots and plenty of drainage holes and fill bottom of pots with crocks, grit or gravel to prevent the holes becoming clogged.
0
0
文章
Dummer. ゛☀
2017年09月15日
Yellowing or reddening of leaves, discoloured or aborting fruits and flowers, and poor plant growth. Fruits can become misshapen and display brown leathery patches.
Plants affected
All plants can be affected.
About Nutrient deficiency
In order to develop and complete their life-cycle without sustaining damage to new growth, flowers or fruit, plants require nutrients.
To maximise efficiency, nutrient supply to plants should be balanced to meet individual needs.
The main nutrients required are carbon, nitrogen, oxygen, hydrogen, phosphorous and potassium.
In addition to these, a number of less essential nutrients known as secondary nutrients are used by a plant to optimise its growth.
There are also many micro nutrients used in tiny amounts by specific plant species.
Main nutrients contribute to production of chlorophyll, fruit set and yield, defence against adverse environmental conditions, leaf loss, and certain diseases. They also aid in the healthy growth of roots, leaves and flowers.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Nutrient deficiency
Nitrogen, potassium and phosphorous fertilisers.
Calcium ammonium nitrate
Ammonium nitrate
Urea
Potassium chloride
Potassium sulphate
Calcium carbonate
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Incorporating farmyard manure, composted plant material, leaf mould and other natural sources of nutrients will ensure healthy plant growth.
Prevention
Establish a regular feeding programme for all potted and hanging basket plants, and those grown in a greenhouse.
Apply a suitable liquid feed to your garden plants at regular intervals when watering.
Apply a suitable granular feed to your lawn at seasonal intervals as indicated.
Incorporate slow release fertiliser granules into all compost used for potting plants.
Dig sources of plant nutrients such as garden compost or well-rotted manure into flower beds and vegetable patches, or place around the bases of existing plants.
Scarify, top-dress, and aerate lawns at the beginning and end of growing seasons.
Plants affected
All plants can be affected.
About Nutrient deficiency
In order to develop and complete their life-cycle without sustaining damage to new growth, flowers or fruit, plants require nutrients.
To maximise efficiency, nutrient supply to plants should be balanced to meet individual needs.
The main nutrients required are carbon, nitrogen, oxygen, hydrogen, phosphorous and potassium.
In addition to these, a number of less essential nutrients known as secondary nutrients are used by a plant to optimise its growth.
There are also many micro nutrients used in tiny amounts by specific plant species.
Main nutrients contribute to production of chlorophyll, fruit set and yield, defence against adverse environmental conditions, leaf loss, and certain diseases. They also aid in the healthy growth of roots, leaves and flowers.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Nutrient deficiency
Nitrogen, potassium and phosphorous fertilisers.
Calcium ammonium nitrate
Ammonium nitrate
Urea
Potassium chloride
Potassium sulphate
Calcium carbonate
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Incorporating farmyard manure, composted plant material, leaf mould and other natural sources of nutrients will ensure healthy plant growth.
Prevention
Establish a regular feeding programme for all potted and hanging basket plants, and those grown in a greenhouse.
Apply a suitable liquid feed to your garden plants at regular intervals when watering.
Apply a suitable granular feed to your lawn at seasonal intervals as indicated.
Incorporate slow release fertiliser granules into all compost used for potting plants.
Dig sources of plant nutrients such as garden compost or well-rotted manure into flower beds and vegetable patches, or place around the bases of existing plants.
Scarify, top-dress, and aerate lawns at the beginning and end of growing seasons.
0
0
文章
Dummer. ゛☀
2017年09月15日
Numerous symptoms are related to herbicide damage, depending on the active ingredients and modes of action of the products used, and all parts of a plant may be affected. Leaves may exhibit distortion, cupping, rolling, yellowing, browning or spotting. Stems may bend, twist, split or swell. Flowers may change size or shape and roots swell and shorten.
Plants affected
All plants – but some are more susceptible than others, for instance, tomatoes and brassicas are prone to damage by hormone or growth-regulating herbicides. Damaged food crops should not be eaten. Some herbicides remain active despite composting or stacking so unless you are sure of the contaminant, you should burn the affected material.
About herbicide damage
Plants can be exposed to herbicides in a number of ways:
From drift when spray herbicide is applied during windy conditions.
Using a contaminated , poorly rinsed sprayer to apply pesticide.
Leaching of herbicides through water in the soil may result in the root structure of nearby plants being affected.
Garden materials such as compost, manure or mulch may be contaminated with a herbicide, causing damage to nearby plants.
Herbicide residue in manure has been an increasing problem in recent years. Try to avoid using bought in manure unless you know where it has come from and how it has been treated.
Soil sterilants are long-lasting herbicides that can persist for years.
Paths often acquire weeds and foliar sprays are available that may cause yellowing on sensitive plants next to the path.
Herbicide applied to a patio may affect tree roots growing under the paving.
Plants vary how they recover from herbicide damage, depending on their vigour and the amount of chemical they have received.
Preventing further damage
Read and follow instructions on the labels of herbicides, using recommended application rates.
Apply liquid sprays very carefully as they can drift in the slightest breeze. Drift may be reduced by lowering spray pressure and spraying close to the target.
Be aware of possible leaching and water runoff when using systemic herbicides.
Avoid the use of soil sterilants as these are active for long periods, and soil contaminated with them may need to be replaced.
Try to use other forms of weed-control, including mulches, hand-weeding or a flame weeder.
Plants affected
All plants – but some are more susceptible than others, for instance, tomatoes and brassicas are prone to damage by hormone or growth-regulating herbicides. Damaged food crops should not be eaten. Some herbicides remain active despite composting or stacking so unless you are sure of the contaminant, you should burn the affected material.
About herbicide damage
Plants can be exposed to herbicides in a number of ways:
From drift when spray herbicide is applied during windy conditions.
Using a contaminated , poorly rinsed sprayer to apply pesticide.
Leaching of herbicides through water in the soil may result in the root structure of nearby plants being affected.
Garden materials such as compost, manure or mulch may be contaminated with a herbicide, causing damage to nearby plants.
Herbicide residue in manure has been an increasing problem in recent years. Try to avoid using bought in manure unless you know where it has come from and how it has been treated.
Soil sterilants are long-lasting herbicides that can persist for years.
Paths often acquire weeds and foliar sprays are available that may cause yellowing on sensitive plants next to the path.
Herbicide applied to a patio may affect tree roots growing under the paving.
Plants vary how they recover from herbicide damage, depending on their vigour and the amount of chemical they have received.
Preventing further damage
Read and follow instructions on the labels of herbicides, using recommended application rates.
Apply liquid sprays very carefully as they can drift in the slightest breeze. Drift may be reduced by lowering spray pressure and spraying close to the target.
Be aware of possible leaching and water runoff when using systemic herbicides.
Avoid the use of soil sterilants as these are active for long periods, and soil contaminated with them may need to be replaced.
Try to use other forms of weed-control, including mulches, hand-weeding or a flame weeder.
0
0
文章
Dummer. ゛☀
2017年09月15日
Shoots, buds and leaves that are wilting and quickly dying back towards the roots, turning black as the plant dies. In some cases discoloured lesions can appear on stems.
Plants affected
Clematis, especially varieties and cultivars that produce large blooms.
About
Clematis wilt is a very common although little understood problem.
The disease is caused by a fungus known as Phoma clematidina.
The fungus causes lesions on the plant’s stems which in contact with water, release their spores that spread the infection.
The disease is thought to also be affected by water-logging, wind and failed grafts.
Sometimes clematis wilt is caused or aggravated by root damage and damage caused by slugs and insects, possibly transporting the spores.
The disease is rarely fatal to the plant and new shoots normally reappear in the next season.
Clematis wilt is often misdiagnosed because damage to the stems and lack of moisture at the roots causes wilting anyway.
Critical points that define Clematis Wilt are: Leaves going black not brown; blackening from the top down; rapid onset.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Clematis wilt
Myclobutanil
Penconazole.
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Cut back affected stems to ground level
Avoid plant stress by keeping the soil well fed and mulched.
Plant more resistant varieties of clematis such as c. montana, C. viticella or C. tangutica.
Plant Clematis deeply, around 6 inches lower than other plants. This encourages more bud development, so the plant can recover more easily if all the stems above ground need to be cut back.
Put a shield around the base of the plants to stop infected water splashing up onto the base of the stems. The top of a fizzy drinks bottle is good for this.
Plants affected
Clematis, especially varieties and cultivars that produce large blooms.
About
Clematis wilt is a very common although little understood problem.
The disease is caused by a fungus known as Phoma clematidina.
The fungus causes lesions on the plant’s stems which in contact with water, release their spores that spread the infection.
The disease is thought to also be affected by water-logging, wind and failed grafts.
Sometimes clematis wilt is caused or aggravated by root damage and damage caused by slugs and insects, possibly transporting the spores.
The disease is rarely fatal to the plant and new shoots normally reappear in the next season.
Clematis wilt is often misdiagnosed because damage to the stems and lack of moisture at the roots causes wilting anyway.
Critical points that define Clematis Wilt are: Leaves going black not brown; blackening from the top down; rapid onset.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on Clematis wilt
Myclobutanil
Penconazole.
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Cut back affected stems to ground level
Avoid plant stress by keeping the soil well fed and mulched.
Plant more resistant varieties of clematis such as c. montana, C. viticella or C. tangutica.
Plant Clematis deeply, around 6 inches lower than other plants. This encourages more bud development, so the plant can recover more easily if all the stems above ground need to be cut back.
Put a shield around the base of the plants to stop infected water splashing up onto the base of the stems. The top of a fizzy drinks bottle is good for this.
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
文章
Dummer. ゛☀
2017年09月15日
Dark brown or black patches surrounded by paler areas on wilted and curled leaves. As the plant weakens, stems can also be affected showing brown discolouration and decomposition of the whole plant soon follows. Underground potato tubers suffer from an all over reddish brown rot that destroys the vegetable and has a foul odour. The fruits on a tomato will soon start rotting after the leaves become infected.
Plants affected
Potatoes, tomatoes and other members of the Solanaceae family.
About
Potato blight and tomato blight are both caused by the same fungal disease.
Once the fungus takes hold it rapidly spreads rapidly by wind-borne spores.
Tomatoes grown under glass will be less likely to succumb as the blight spores do not easily get inside greenhouses.
The fungus spreads easiest when weather conditions are above 10 degrees centigrade and when there is high humidity in the air.
Tubers carrying the disease which are not incinerated can become ‘Primary Infectors’ if they are replanted and conditions are ideal for the fungus.
Periods of hot dry weather can subdue and delay potato blight symptoms.
Blight cannot survive in soil or fully composted plant material. It over-winters in living plant material and is spread on the wind the following year.
The most common way to allow blight to remain in your garden is through ‘volunteer potatoes’. These are tiny potato tubers which survive over the winter in the soil or the compost heap and shoot up again in the following spring.
Treatment
Chemical
There are a number of copper based fungicides, including Bordeaux mixture which will have some effect. They mainly work in a preventative way so waiting until the first symptoms appear may be too late.
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regularly observe crops to check for damage and remove all affected plants immediately and incinerate.
Keep weeds under control that could be alternative host plants e.g. Deadly Night Shade.
Avoid growing at times of year when weather conditions are favourable for the fungus.
At the first sign of infection, cut down all the tops of potato plants (known as the haulms) and burn or fully compost them. Then leave the tubers in the ground for a few days before lifting them to allow any blight spores on the soil surface to die off.
Do not compost infected or unused tubers.
Tomatoes should be harvested as soon as blight becomes apparent even if they’re still green (make chutney!)
Preventing Further Infection
Grow resistant varieties such as: Potatoes ‘Axona’ or ‘Mira’ and Tomato ‘Ferline’.
Plants affected
Potatoes, tomatoes and other members of the Solanaceae family.
About
Potato blight and tomato blight are both caused by the same fungal disease.
Once the fungus takes hold it rapidly spreads rapidly by wind-borne spores.
Tomatoes grown under glass will be less likely to succumb as the blight spores do not easily get inside greenhouses.
The fungus spreads easiest when weather conditions are above 10 degrees centigrade and when there is high humidity in the air.
Tubers carrying the disease which are not incinerated can become ‘Primary Infectors’ if they are replanted and conditions are ideal for the fungus.
Periods of hot dry weather can subdue and delay potato blight symptoms.
Blight cannot survive in soil or fully composted plant material. It over-winters in living plant material and is spread on the wind the following year.
The most common way to allow blight to remain in your garden is through ‘volunteer potatoes’. These are tiny potato tubers which survive over the winter in the soil or the compost heap and shoot up again in the following spring.
Treatment
Chemical
There are a number of copper based fungicides, including Bordeaux mixture which will have some effect. They mainly work in a preventative way so waiting until the first symptoms appear may be too late.
Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.
Organic
Regularly observe crops to check for damage and remove all affected plants immediately and incinerate.
Keep weeds under control that could be alternative host plants e.g. Deadly Night Shade.
Avoid growing at times of year when weather conditions are favourable for the fungus.
At the first sign of infection, cut down all the tops of potato plants (known as the haulms) and burn or fully compost them. Then leave the tubers in the ground for a few days before lifting them to allow any blight spores on the soil surface to die off.
Do not compost infected or unused tubers.
Tomatoes should be harvested as soon as blight becomes apparent even if they’re still green (make chutney!)
Preventing Further Infection
Grow resistant varieties such as: Potatoes ‘Axona’ or ‘Mira’ and Tomato ‘Ferline’.
0
0
文章
Dummer. ゛☀
2017年09月15日
Yellowing and often disfigured leaves, which are caused by whitefly feeding on the plant cells. Whitefly secrete sticky honeydew deposits as they feed which fall on to the surrounding foliage. This causes dark sooty mould to develop on the leaves.
Plants affected
Whitefly colonies affect a wide range of vegetables, ornamental plants and trees.
About whiteflies
Whitefly adults are tiny, moth-like insects that feed on plant sap. They have two pairs of white wings that fold back over their abdomen when at rest.
Over 1400 species of whitefly have been recorded worldwide and 56 of these have been found in Europe.
Development of egg to adult takes around three to four weeks, depending on the temperature
Females usually lay up to 200 eggs on the underside of leaves, often in neat circles.
Eggs hatch into larvae that initially crawl over the leaf surface for a few hours then settle to feed on plant sap.
The larvae are small and scale-like in appearance.
After the first skin-shed, the larvae become fixed to the leaf by their feeding tubes until they turn into pupae from which the adults emerge.
Glasshouse whitefly, Trialeurodes vaporariorum, as their name suggests, usually infest plants grown indoors and under glass such as tomato, cucumber, pepper and many ornamentals.
Cabbage whitefly, Aleyrodes proletella, is a common pest in southern England even in the colder winter months. It's similar to glasshouse whitefly, but has grey spots in the centre of each wing, and attacks only cabbages and other brassicas.
Tobacco whitefly, Bemisia tabaci, is a notifiable pest that has to be reported to DEFRA Plant Health if found. It occasionally appears in the UK on imported ornamentals and cut flowers. In southern Europe, the tobacco whitefly causes serious damage to horticultural crops by transmitting plant viruses. It's similar in appearance to the glasshouse whitefly, although smaller and less triangular in shape when at rest.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on whiteflies
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
Inspect your plants every day and thoroughly.
Adult whiteflies feed and lay eggs on the new growth of plants, so these areas need to be inspected first. If adults are present, then an organic ,approved natural fatty acid or natural soap product will control them.
If you spot adult whiteflies, particularly on older plants, then they're likely to have emerged from an infestation of larvae and pupae on the lower leaves. Carefully inspect the lower leaves and remove and destroy any that are infested with whitefly larval scales.
Nettings and fleeces can be used to cover greenhouse vents and stop whiteflies spreading on to susceptible plants.
Use natural enemies such as spiders, which catch large numbers of adult whiteflies in their webs. Ladybirds, hoverfly and lacewing larvae will also eat whitefly.
For greenhouse plants use the parasitic wasp Encarsia formosa which is commercially available. This will attack and kill the larvae of glasshouse whitefly.
Yellow sticky traps should be placed within a greenhouse to catch adult whitefly.
Prevention
Check plants every day for signs of whitefly infestation and deal with them as soon as they appear.
Monitor whitefly activity by hanging yellow sticky traps among greenhouse and conservatory plants.
Be wary of weeds that can often host whitefly within or near cultivated plants.
Encourage natural enemies into the garden.
Don't use broad spectrum insecticides that kill beneficial insects as well as whiteflies.
Destroy leaves that have large infestations of whitefly larvae since many whitefly adults will still develop and hatch from detached and discarded leaves.
Encourage insectivorous birds by hanging feeders during the winter months and provide nesting boxes in the spring.
Plants affected
Whitefly colonies affect a wide range of vegetables, ornamental plants and trees.
About whiteflies
Whitefly adults are tiny, moth-like insects that feed on plant sap. They have two pairs of white wings that fold back over their abdomen when at rest.
Over 1400 species of whitefly have been recorded worldwide and 56 of these have been found in Europe.
Development of egg to adult takes around three to four weeks, depending on the temperature
Females usually lay up to 200 eggs on the underside of leaves, often in neat circles.
Eggs hatch into larvae that initially crawl over the leaf surface for a few hours then settle to feed on plant sap.
The larvae are small and scale-like in appearance.
After the first skin-shed, the larvae become fixed to the leaf by their feeding tubes until they turn into pupae from which the adults emerge.
Glasshouse whitefly, Trialeurodes vaporariorum, as their name suggests, usually infest plants grown indoors and under glass such as tomato, cucumber, pepper and many ornamentals.
Cabbage whitefly, Aleyrodes proletella, is a common pest in southern England even in the colder winter months. It's similar to glasshouse whitefly, but has grey spots in the centre of each wing, and attacks only cabbages and other brassicas.
Tobacco whitefly, Bemisia tabaci, is a notifiable pest that has to be reported to DEFRA Plant Health if found. It occasionally appears in the UK on imported ornamentals and cut flowers. In southern Europe, the tobacco whitefly causes serious damage to horticultural crops by transmitting plant viruses. It's similar in appearance to the glasshouse whitefly, although smaller and less triangular in shape when at rest.
Treatment
Chemical
Products containing the following chemical ingredients are all effective on whiteflies
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
Inspect your plants every day and thoroughly.
Adult whiteflies feed and lay eggs on the new growth of plants, so these areas need to be inspected first. If adults are present, then an organic ,approved natural fatty acid or natural soap product will control them.
If you spot adult whiteflies, particularly on older plants, then they're likely to have emerged from an infestation of larvae and pupae on the lower leaves. Carefully inspect the lower leaves and remove and destroy any that are infested with whitefly larval scales.
Nettings and fleeces can be used to cover greenhouse vents and stop whiteflies spreading on to susceptible plants.
Use natural enemies such as spiders, which catch large numbers of adult whiteflies in their webs. Ladybirds, hoverfly and lacewing larvae will also eat whitefly.
For greenhouse plants use the parasitic wasp Encarsia formosa which is commercially available. This will attack and kill the larvae of glasshouse whitefly.
Yellow sticky traps should be placed within a greenhouse to catch adult whitefly.
Prevention
Check plants every day for signs of whitefly infestation and deal with them as soon as they appear.
Monitor whitefly activity by hanging yellow sticky traps among greenhouse and conservatory plants.
Be wary of weeds that can often host whitefly within or near cultivated plants.
Encourage natural enemies into the garden.
Don't use broad spectrum insecticides that kill beneficial insects as well as whiteflies.
Destroy leaves that have large infestations of whitefly larvae since many whitefly adults will still develop and hatch from detached and discarded leaves.
Encourage insectivorous birds by hanging feeders during the winter months and provide nesting boxes in the spring.
0
0
文章
Dummer. ゛☀
2017年09月15日
Whiteflies are harmful to both outdoor and indoor plants by sucking plant sap. Under certain conditions, they can also transmit disease. The whitefly parasite (Encarsia formosa) lays its eggs — as many as 50 to 100 — in both pupae and later larval stages of the white fly, destroying them before they can become adults. The host larva turns black as the parasite develops. It emerges, depending on conditions, in about two weeks. The adults will also feed on the larval juices released when they puncture the larvae.
Shop our large selection of beneficial insects, including whitefly parasites, at Planet Natural. One strip of cards — 500 parasitic wasps — treats up to 250 square feet and costs $29.50 with USPS Priority Mail shipping included!
Attracted to the flies by the smell of the honeydew they produce, E. formosa is an efficient biological control of whitefly and one of the most cost effective ways to control greenhouse and indoor infestations of the pest.
Humidity and strong light encourage the parasite’s activity. Temperature is also key as the parasite will not fly and seek out new prey at temperatures under 62 degrees. Its preference for warm, humid, well-lit conditions make the whitefly parasite the perfect solution for indoor and greenhouse whitefly problems.
Depending on pest levels, the following release rates have been established:
2-4 per square foot of infested area
1-2 per plant when pests are first noticed
Whitefly parasites are shipped as mature pupae in host eggs, glued to a paper card and almost ready to hatch as adult parasitic wasps. If pest levels are high, use a least-toxic, short-lived natural pesticide (insecticidal soap, botanical insecticide) to establish control, then release beneficials 2-3 weeks later to maintain control.
Shop our large selection of beneficial insects, including whitefly parasites, at Planet Natural. One strip of cards — 500 parasitic wasps — treats up to 250 square feet and costs $29.50 with USPS Priority Mail shipping included!
Attracted to the flies by the smell of the honeydew they produce, E. formosa is an efficient biological control of whitefly and one of the most cost effective ways to control greenhouse and indoor infestations of the pest.
Humidity and strong light encourage the parasite’s activity. Temperature is also key as the parasite will not fly and seek out new prey at temperatures under 62 degrees. Its preference for warm, humid, well-lit conditions make the whitefly parasite the perfect solution for indoor and greenhouse whitefly problems.
Depending on pest levels, the following release rates have been established:
2-4 per square foot of infested area
1-2 per plant when pests are first noticed
Whitefly parasites are shipped as mature pupae in host eggs, glued to a paper card and almost ready to hatch as adult parasitic wasps. If pest levels are high, use a least-toxic, short-lived natural pesticide (insecticidal soap, botanical insecticide) to establish control, then release beneficials 2-3 weeks later to maintain control.
0
0
文章
Dummer. ゛☀
2017年09月15日
Hemp and russet mites are part of the eriophyid family of mites. Among the 100 or so plant-specific eriophyid species, including gall, rust, and blister mites, the tomato-attacking, microscopic russet mite is among the hardest to detect. Visible, if then, only in clusters, a single mite is too tiny to be seen by the human eye without magnification of 10x and higher. Their near invisibility makes these mites a particular threat to become established in your garden before you realize it.
Unlike spider mites, these voracious plant pests leave no webbing or other secretions when present. Visible damage to the plant is the first indication of its presence a damage often mistaken for mineral and other nutritional deficits.
Seen through a lens, russet-hemp mites are tapered, translucent, wedge-shaped cylinders that take on a yellow tint, especially in groups. Unlike most varieties of mites, eriophyid, including russet mites, have only two pairs of legs.
Like spider mites and others, they are increasing their range and are now common in places not previously seen. Because of their size, they’re effectively dispersed by wind.
Crop specific, they tend to multiply in areas of intensive growing, like the tomato raising regions of Florida, and also do quite well indoors where warm, moist environments facilitate rapid reproduction. In the past decade, they have spread from growers in California north into Oregon.
Lifecycle
Females over winter just inside stems of the plants they infest or where twigs are joined to stems. Translucent eggs, nearly adult in size, are laid in spring and go through two nymph stages, both little different than the adult. The mites produce multiple, over-lapping generations through the course of a season, maturing in as little as eight days in warm, humid conditions.
Damage
Mites are sap suckers working at the cellular level. Damage typically appears first at the bottom of plants and moves upward as they feed. Lower leaves begin to yellow and curl, the leaf droops and the stem discolors. As the plant’s nourishment is sucked away, less vigorous green growth and flowering is observed. The tiny mites, in increasing numbers, spread to all parts of the plant. The mites seem particularly attracted to flower resins and will congregate in flowers and blossoms where they can effectively hide and do great damage. If left unchecked, the mites will eventually sap the entire plant.
Russet Mite Control
The best controls for both indoor and outdoor growers are preventive methods. Make sure you don’t introduce mites into your grow space by bringing in infected plants or contaminated potting soil that may carry female mites or eggs. Regular and close scrutiny of your plants, especially around the leaves nearest the soil line if outdoors, or anywhere a plant is flowering, is crucial to early detection. What might appear to be an iron or magnesium deficiency may well be an infestation of russet mites. If in doubt, treat for mites as well as adjusting nutrient solutions or amending soil. Finding and removing mites in their first generation, a period that can be short as a week under the right conditions, can short-circuit a cascade of generations once the mites begin laying eggs.
Many of the precautions and treatments used on spider mites also apply to this pest. Inspection of plants is crucial during treatment. Look to see if damage has stopped. Remove all damaged leaves, stems, and even entire plants and dispose in a way that won’t spread the tiny creatures or its eggs.
Outdoor Plants:
Russet mites are most frequently found in outdoor container plantings. This suggests that they’re introduced both in potting soils and plants brought into the garden. Use only dependable, high-quality potting medium and plants from a nursery you trust. Don’t be afraid to ask if mites have been a problem. Even if they’ve been dealt with and the plant shows no signs of damage, eggs may still exist in the soil.
Introducing beneficial nematodes just as soil temperatures begin to warm and ahead of planting can help destroy eggs that are in the soil and nymphs once they hatch. Apply a second round of vermiculite-carried nematodes if damage to lowest leaves is spotted.
Avoid over-fertilizing plants. Mites are attracted to vigorous green growth that comes of too much nitrogen.
Periodic releases of predatory mites can blunt infestations, giving you time to deal with them. (Yes, the same spray mentioned below will also kill beneficial mites.)
Because of their near invisibility, it’s difficult to apply insecticidal soaps to suspected mite infestations. Home-made sprays using garlic, hot peppers, or citrus oils will not usually take down mites but may provide some deterrent. (Because they often arrive in the wind, russet-hemp mites aren’t easily deterred.)
Neem oil will repel and kill mites. It should be applied at first signs of damage.
Pyrethrum sprays have proven effective in killing mites but require complete coverage to ensure that none of the microscopic pests are overlooked. Tailor applications to the lifecycle of the mite. Spraying once a week — once every five days in warm conditions — for three to four weeks should cover adults, emerging nymphs, and eggs.
No matter which method you’re using, close inspection of plants during treatment is crucial. Use a lens of 14X magnification or larger to see mites gathered at the center of curled leaves, at stem junctures, or in flowers. Don’t wait to see how effective one treatment is before continuing or using another. Once infestations spread up plants, it’s almost impossible to save the plant.
Don’t hesitate to discard entire plants, even if they’re not entirely affected. While you’re treating affected plants, the mites are hurriedly spreading to others.
Prevent spreading mites. Discard infested plants in plastic bags and dispose of them in sealed garbage containers.
Indoor Plants:
Do not bring uninspected plants or plants from any grower who’s had previous problems with mites into your grow space. This is especially important, whether taking clones or tomato starts from friends and professionals. Know your grower.
Keep a clean grow space. Don’t introduce unnecessary tools used outside or suspect soil or growing mediums.
Periodic releases of spider mite predators in a greenhouse can help keep pests at bay.
At the first sign of mites, reduce their breeding environment by adjusting room temperatures and moisture content as much as possible. This will slow the breeding cycle, buying you time to inspect and treat plants before the mites next generation is spawned.
Azamax will discourage mites from feeding and slow their breeding cycle, especially helpful if you’re moving towards harvest.
Neem oil and pyrethrum/ canola oil sprays, used as above, will knock down mite infestations with repeated use.
If your grow space has been infected, clean it from top to bottom. Scrub benches and other equipment with a mild bleach solution (1:10 bleach-to-water solution is said to be safe for cleaning according to the Centers For Disease Control), sterilize all hydroponic equipment, throw away any soil that can’t be sanitized, and leave nothing that was in the space during the infestation unscrubbed. The invisible eggs of this troublesome pest can survive in tiny, unseen places.
Unlike spider mites, these voracious plant pests leave no webbing or other secretions when present. Visible damage to the plant is the first indication of its presence a damage often mistaken for mineral and other nutritional deficits.
Seen through a lens, russet-hemp mites are tapered, translucent, wedge-shaped cylinders that take on a yellow tint, especially in groups. Unlike most varieties of mites, eriophyid, including russet mites, have only two pairs of legs.
Like spider mites and others, they are increasing their range and are now common in places not previously seen. Because of their size, they’re effectively dispersed by wind.
Crop specific, they tend to multiply in areas of intensive growing, like the tomato raising regions of Florida, and also do quite well indoors where warm, moist environments facilitate rapid reproduction. In the past decade, they have spread from growers in California north into Oregon.
Lifecycle
Females over winter just inside stems of the plants they infest or where twigs are joined to stems. Translucent eggs, nearly adult in size, are laid in spring and go through two nymph stages, both little different than the adult. The mites produce multiple, over-lapping generations through the course of a season, maturing in as little as eight days in warm, humid conditions.
Damage
Mites are sap suckers working at the cellular level. Damage typically appears first at the bottom of plants and moves upward as they feed. Lower leaves begin to yellow and curl, the leaf droops and the stem discolors. As the plant’s nourishment is sucked away, less vigorous green growth and flowering is observed. The tiny mites, in increasing numbers, spread to all parts of the plant. The mites seem particularly attracted to flower resins and will congregate in flowers and blossoms where they can effectively hide and do great damage. If left unchecked, the mites will eventually sap the entire plant.
Russet Mite Control
The best controls for both indoor and outdoor growers are preventive methods. Make sure you don’t introduce mites into your grow space by bringing in infected plants or contaminated potting soil that may carry female mites or eggs. Regular and close scrutiny of your plants, especially around the leaves nearest the soil line if outdoors, or anywhere a plant is flowering, is crucial to early detection. What might appear to be an iron or magnesium deficiency may well be an infestation of russet mites. If in doubt, treat for mites as well as adjusting nutrient solutions or amending soil. Finding and removing mites in their first generation, a period that can be short as a week under the right conditions, can short-circuit a cascade of generations once the mites begin laying eggs.
Many of the precautions and treatments used on spider mites also apply to this pest. Inspection of plants is crucial during treatment. Look to see if damage has stopped. Remove all damaged leaves, stems, and even entire plants and dispose in a way that won’t spread the tiny creatures or its eggs.
Outdoor Plants:
Russet mites are most frequently found in outdoor container plantings. This suggests that they’re introduced both in potting soils and plants brought into the garden. Use only dependable, high-quality potting medium and plants from a nursery you trust. Don’t be afraid to ask if mites have been a problem. Even if they’ve been dealt with and the plant shows no signs of damage, eggs may still exist in the soil.
Introducing beneficial nematodes just as soil temperatures begin to warm and ahead of planting can help destroy eggs that are in the soil and nymphs once they hatch. Apply a second round of vermiculite-carried nematodes if damage to lowest leaves is spotted.
Avoid over-fertilizing plants. Mites are attracted to vigorous green growth that comes of too much nitrogen.
Periodic releases of predatory mites can blunt infestations, giving you time to deal with them. (Yes, the same spray mentioned below will also kill beneficial mites.)
Because of their near invisibility, it’s difficult to apply insecticidal soaps to suspected mite infestations. Home-made sprays using garlic, hot peppers, or citrus oils will not usually take down mites but may provide some deterrent. (Because they often arrive in the wind, russet-hemp mites aren’t easily deterred.)
Neem oil will repel and kill mites. It should be applied at first signs of damage.
Pyrethrum sprays have proven effective in killing mites but require complete coverage to ensure that none of the microscopic pests are overlooked. Tailor applications to the lifecycle of the mite. Spraying once a week — once every five days in warm conditions — for three to four weeks should cover adults, emerging nymphs, and eggs.
No matter which method you’re using, close inspection of plants during treatment is crucial. Use a lens of 14X magnification or larger to see mites gathered at the center of curled leaves, at stem junctures, or in flowers. Don’t wait to see how effective one treatment is before continuing or using another. Once infestations spread up plants, it’s almost impossible to save the plant.
Don’t hesitate to discard entire plants, even if they’re not entirely affected. While you’re treating affected plants, the mites are hurriedly spreading to others.
Prevent spreading mites. Discard infested plants in plastic bags and dispose of them in sealed garbage containers.
Indoor Plants:
Do not bring uninspected plants or plants from any grower who’s had previous problems with mites into your grow space. This is especially important, whether taking clones or tomato starts from friends and professionals. Know your grower.
Keep a clean grow space. Don’t introduce unnecessary tools used outside or suspect soil or growing mediums.
Periodic releases of spider mite predators in a greenhouse can help keep pests at bay.
At the first sign of mites, reduce their breeding environment by adjusting room temperatures and moisture content as much as possible. This will slow the breeding cycle, buying you time to inspect and treat plants before the mites next generation is spawned.
Azamax will discourage mites from feeding and slow their breeding cycle, especially helpful if you’re moving towards harvest.
Neem oil and pyrethrum/ canola oil sprays, used as above, will knock down mite infestations with repeated use.
If your grow space has been infected, clean it from top to bottom. Scrub benches and other equipment with a mild bleach solution (1:10 bleach-to-water solution is said to be safe for cleaning according to the Centers For Disease Control), sterilize all hydroponic equipment, throw away any soil that can’t be sanitized, and leave nothing that was in the space during the infestation unscrubbed. The invisible eggs of this troublesome pest can survive in tiny, unseen places.
0
0
文章
Dummer. ゛☀
2017年09月15日
Crown gall is a common plant disease caused by the soil-borne bacterium Agrobacterium tumefaciens. It is found throughout the world and occurs on woody shrubs and herbaceous plants including grapes, raspberries, blackberries and roses.
Crown gall symptoms include round, wart-like growths — 2 inches or larger in diameter — that appear at or just above the soil line, or on lower branches and stems. Plants with several galls may be unable to move water and nutrients up the trunk and become weakened, stunted and unproductive. Young plants can be killed by developing gall tissue.
The bacteria responsible for crown gall can persist in the soil for many years and are released when galls become saturated with moisture or as older galls decompose. Susceptible plants are infected through fresh wounds or abrasions, many of which are a result of pruning, freeze injury, soil insects, cultivation and other factors that may damage plants. Nursery stock is often infected through grafting and budding scars.
Treatment
Select resistant cultivars when possible and purchase plants from a reputable nursery.
Do not buy plants that shows signs of swelling or galling.
When caring for susceptible plants, avoid injury or pruning wounds that may come in contact with the soil.
Use Tree Wrap to protect against string trimmer damage and keep your garden tools clean.
Provide winter protection with natural burlap so bark does not crack.
In many cases, existing galls can be removed with a sharp pruning knife. Destroy the infected plant tissue and treat the wound with pruning sealer. If the plant does not recover, remove and destroy it.
Crown gall symptoms include round, wart-like growths — 2 inches or larger in diameter — that appear at or just above the soil line, or on lower branches and stems. Plants with several galls may be unable to move water and nutrients up the trunk and become weakened, stunted and unproductive. Young plants can be killed by developing gall tissue.
The bacteria responsible for crown gall can persist in the soil for many years and are released when galls become saturated with moisture or as older galls decompose. Susceptible plants are infected through fresh wounds or abrasions, many of which are a result of pruning, freeze injury, soil insects, cultivation and other factors that may damage plants. Nursery stock is often infected through grafting and budding scars.
Treatment
Select resistant cultivars when possible and purchase plants from a reputable nursery.
Do not buy plants that shows signs of swelling or galling.
When caring for susceptible plants, avoid injury or pruning wounds that may come in contact with the soil.
Use Tree Wrap to protect against string trimmer damage and keep your garden tools clean.
Provide winter protection with natural burlap so bark does not crack.
In many cases, existing galls can be removed with a sharp pruning knife. Destroy the infected plant tissue and treat the wound with pruning sealer. If the plant does not recover, remove and destroy it.
0
0
文章
Dummer. ゛☀
2017年09月15日
Affecting most brassica crops (cabbage, broccoli, cauliflower, etc.), club root is a serious plant disease in North American home gardens. It is caused by the soil-borne fungus Plasmodiophora brassicae which infects susceptible plants through root hairs. Diseased roots become swollen, misshapen and deformed (clubbed) often cracking and rotting. As a result, plants have difficulty absorbing water and nutrients properly.
Plants often grow poorly and wilt during the heat of the day; plants often revive during cool nights. Outer leaves may turn yellow, purple or brown. Club root will reduce yields and can cause total crop failure.
Fungal spores can be spread by wind, water and garden tools. Disease development can occur over a wide range of conditions, but is favored by excessive moisture, low soil pH and soil temperatures between 64 and 77˚F. Spores can survive in the soil for as many as 10 years.
Treatment
Fungicides will NOT treat this soil-dwelling micro-organism.
Choose resistant cultivars when possible.
Try to prevent the occurrence of this disease by keeping a clean garden and rotating crops.
Keep in mind that the disease spores can persist in the soil for up to 20 years. If club root is present you may want to solarize the soil.*
Control susceptible weeds — mustard, radish, shepherd’s purse — that may be infected to reduce potential buildup of the disease.
Carefully remove infected plants and sterilize garden tools (one part bleach to 4 parts water) after use.
Raise your soil’s pH to a more alkaline 7.2 by mixing oyster shell or dolomite lime into your garden in the fall. Simple and affordable soil test kits are available to check pH often.
* To solarize your soil, you must leave a clear plastic tarp on the soil surface for 4-6 weeks during the hottest part of the year. Soil solarization will reduce or eliminate many soil inhabiting pests including nematodes, fungi, insects, weeds and weed seeds.
Plants often grow poorly and wilt during the heat of the day; plants often revive during cool nights. Outer leaves may turn yellow, purple or brown. Club root will reduce yields and can cause total crop failure.
Fungal spores can be spread by wind, water and garden tools. Disease development can occur over a wide range of conditions, but is favored by excessive moisture, low soil pH and soil temperatures between 64 and 77˚F. Spores can survive in the soil for as many as 10 years.
Treatment
Fungicides will NOT treat this soil-dwelling micro-organism.
Choose resistant cultivars when possible.
Try to prevent the occurrence of this disease by keeping a clean garden and rotating crops.
Keep in mind that the disease spores can persist in the soil for up to 20 years. If club root is present you may want to solarize the soil.*
Control susceptible weeds — mustard, radish, shepherd’s purse — that may be infected to reduce potential buildup of the disease.
Carefully remove infected plants and sterilize garden tools (one part bleach to 4 parts water) after use.
Raise your soil’s pH to a more alkaline 7.2 by mixing oyster shell or dolomite lime into your garden in the fall. Simple and affordable soil test kits are available to check pH often.
* To solarize your soil, you must leave a clear plastic tarp on the soil surface for 4-6 weeks during the hottest part of the year. Soil solarization will reduce or eliminate many soil inhabiting pests including nematodes, fungi, insects, weeds and weed seeds.
0
0
