文章
Dummer. ゛☀
2017年09月19日
Jade Plant (Crassula ovata) are a classic houseplant, especially for the neglectful home owner. It prefer bright light and occasional water in the warm season, but other than that the plants are fairly self-sufficient. In good conditions, you may still find white spots on Jade Plant leaves; but if the plant’s overall health is good, you should not worry too much. What causes white spots on Jade Plant? It may be a natural phenomenon or a bit of a fungal disease, but either way, there are easy methods to define and deal with the problem.
What Causes White Spots?
The few times I have discovered white spots on my Jade Plant, I simply rubbed them off lightly and the plant was no worse for wear. The actual cause of the white spots on Jade Plant leaves might be powdery mildew, or even a condition where the plant stores salts and “sweats” the excess out through its leaves. One cause has a quick fix and the other requires some cultural adjustment and treatment. Both are really not all that harmful to your plant and learning how to get rid of white spots on Jade Plants is a matter of some quick steps.
Powdery Mildew
Most gardeners are familiar with powdery mildew. It occurs when there is low light, improper circulation, cooler temperatures and excess humidity. Overhead watering leaves foliage damp, which in winter months tends to stay moist for a long period. This promotes the formation of fungal spores that cause powdery mildew.
Avoid overhead watering and use a fan to increase circulation. Pinch off affected foliage and discard it. A solution of baking soda and vinegar is how to get rid of white spots on jade plants with powdery mildew. Spray on the leaves but ensure the leaves dry within a few hours.
Excess Salts
All plants uptake water through their roots with a few rare exceptions. Jade Plants store water in their fleshy leaves, which makes them ideal species in arid zones. They capture infrequent rainwater and store it until they need it much like a squirrel hoarding nuts. This gives the leaves their plump appearance.
Rain and ground water alike capture salt from the air and soil. When you water with a salty solution, the trapped moisture will go through the leaves during transpiration and the evaporated moisture will leave a salt residue on the leaf. Therefore, your Jade Plant has white spots on the surface of the pads. A soft, lightly moist cloth can wipe these away easily and restore the appearance of the foliage.
Other Reasons for White Spots
Jade Plants often get a condition called Oedema, where the roots take up water faster than the plant can use it. This causes corky blisters to form on the foliage. Reducing water should prevent the condition, but the blisters will remain.
Rarely, you may find a Jade Plant has white spots which are actually insects. Mealybugs have a whitish silver fuzzy exterior. If your white spots are moving under close observation, take action and seclude the Jade Plant from other plants.
The spots may also be a variety of scale with silvery bodies. Both can be conquered with a systemic insecticide formulated for houseplants or by dabbing them with a 70 percent solution of rubbing alcohol.
Jade Plants are not usually prone to insect infestations, but if you put the plant outdoors for the summer, take a good look at it before bringing it indoors and infecting your other flora.
What Causes White Spots?
The few times I have discovered white spots on my Jade Plant, I simply rubbed them off lightly and the plant was no worse for wear. The actual cause of the white spots on Jade Plant leaves might be powdery mildew, or even a condition where the plant stores salts and “sweats” the excess out through its leaves. One cause has a quick fix and the other requires some cultural adjustment and treatment. Both are really not all that harmful to your plant and learning how to get rid of white spots on Jade Plants is a matter of some quick steps.
Powdery Mildew
Most gardeners are familiar with powdery mildew. It occurs when there is low light, improper circulation, cooler temperatures and excess humidity. Overhead watering leaves foliage damp, which in winter months tends to stay moist for a long period. This promotes the formation of fungal spores that cause powdery mildew.
Avoid overhead watering and use a fan to increase circulation. Pinch off affected foliage and discard it. A solution of baking soda and vinegar is how to get rid of white spots on jade plants with powdery mildew. Spray on the leaves but ensure the leaves dry within a few hours.
Excess Salts
All plants uptake water through their roots with a few rare exceptions. Jade Plants store water in their fleshy leaves, which makes them ideal species in arid zones. They capture infrequent rainwater and store it until they need it much like a squirrel hoarding nuts. This gives the leaves their plump appearance.
Rain and ground water alike capture salt from the air and soil. When you water with a salty solution, the trapped moisture will go through the leaves during transpiration and the evaporated moisture will leave a salt residue on the leaf. Therefore, your Jade Plant has white spots on the surface of the pads. A soft, lightly moist cloth can wipe these away easily and restore the appearance of the foliage.
Other Reasons for White Spots
Jade Plants often get a condition called Oedema, where the roots take up water faster than the plant can use it. This causes corky blisters to form on the foliage. Reducing water should prevent the condition, but the blisters will remain.
Rarely, you may find a Jade Plant has white spots which are actually insects. Mealybugs have a whitish silver fuzzy exterior. If your white spots are moving under close observation, take action and seclude the Jade Plant from other plants.
The spots may also be a variety of scale with silvery bodies. Both can be conquered with a systemic insecticide formulated for houseplants or by dabbing them with a 70 percent solution of rubbing alcohol.
Jade Plants are not usually prone to insect infestations, but if you put the plant outdoors for the summer, take a good look at it before bringing it indoors and infecting your other flora.
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文章
Dummer. ゛☀
2017年09月19日
Agave americana, commonly called the Century Plant, is a succulent desert plant native to Mexico. It can grow outdoors year-round in U.S. Department of Agriculture plant hardiness zones 8 to 10. The largest of the Agaves, mature plants range from 5 to 7 feet (1.5 to 2.1 m) tall with 8- to 12-foot (20 to 30 cm) spreads. Century Plant makes a dramatic accent plant with its blue or blue-gray leaves, black spines and showy, yellow-green flowers. Despite its renowned hardiness, Century Plant can still suffer from a few cultural, disease and pest problems.
Cultural Problems
Century Plant can tolerate various cultural conditions as long as it is planted in fast-draining soils. Poor-draining soils make the plant susceptible to the fungal pathogens that cause root rot. This Agave can survive down to 15 degrees Fahrenheit (-15 degrees Celsius), but the broad, fleshy leaves will suffer from freeze damage if the temperature drops below freezing for several hours. Freeze-damaged tissue turns black, dries out and looks unsightly. The damage can’t be repaired, but most Century Plants will recover. Prevent freeze damage by covering the plant with a light, cotton sheet when your area is expecting a freeze.
Diseases
Although Century Plant isn’t associated with any serious disease problems, root rot can be problematic in poor-draining or overly moist soils. Root rot causes wilting, stunted growth and discolored leaves. Unfortunately, this fungal infection cannot be treated once it occurs. Anthracnose is another occasional problem that occurs when fungal pathogens thrive in overly moist soil conditions. This disease causes lesions to form on the leaves, with red or orange spore masses developing inside the sores. Remove any anthracnose-infected plant tissue promptly to prevent the disease from spreading.
Pest Problems
For the most part, Century Plant doesn’t have serious pest problems, but there is one exception. Root rot typically goes hand-in-hand with agave snout weevil infestations. Adult females chew through to the base of the plant to lay their eggs in the infected plant tissue. The larvae hatch and burrow their way into the heart of the plant. Severely infected Century Plants look wrinkled or shriveled and emit a foul odor. The rotting plant tissue eventually collapses and the plant dies. Controlling Agave snout weevil is difficult, but spraying the base of the plant with a broad-spectrum insecticide in the spring often helps prevent infestations from occurring.
Recommendations
Avoid Century Plant problems by providing your plant with the best possible growing conditions. These succulents perform best when planted in fully sunny areas, although they can handle some light shade. Century Plant grows best in sandy or gritty soils with dry to medium moisture. These drought-tolerant plants only need occasional watering in dry summer weather to remain healthy. Give the plant plenty of room to grow and make sure it is planted away from foot traffic. The sharp spines can poke you and cause your skin to swell painfully.
Cultural Problems
Century Plant can tolerate various cultural conditions as long as it is planted in fast-draining soils. Poor-draining soils make the plant susceptible to the fungal pathogens that cause root rot. This Agave can survive down to 15 degrees Fahrenheit (-15 degrees Celsius), but the broad, fleshy leaves will suffer from freeze damage if the temperature drops below freezing for several hours. Freeze-damaged tissue turns black, dries out and looks unsightly. The damage can’t be repaired, but most Century Plants will recover. Prevent freeze damage by covering the plant with a light, cotton sheet when your area is expecting a freeze.
Diseases
Although Century Plant isn’t associated with any serious disease problems, root rot can be problematic in poor-draining or overly moist soils. Root rot causes wilting, stunted growth and discolored leaves. Unfortunately, this fungal infection cannot be treated once it occurs. Anthracnose is another occasional problem that occurs when fungal pathogens thrive in overly moist soil conditions. This disease causes lesions to form on the leaves, with red or orange spore masses developing inside the sores. Remove any anthracnose-infected plant tissue promptly to prevent the disease from spreading.
Pest Problems
For the most part, Century Plant doesn’t have serious pest problems, but there is one exception. Root rot typically goes hand-in-hand with agave snout weevil infestations. Adult females chew through to the base of the plant to lay their eggs in the infected plant tissue. The larvae hatch and burrow their way into the heart of the plant. Severely infected Century Plants look wrinkled or shriveled and emit a foul odor. The rotting plant tissue eventually collapses and the plant dies. Controlling Agave snout weevil is difficult, but spraying the base of the plant with a broad-spectrum insecticide in the spring often helps prevent infestations from occurring.
Recommendations
Avoid Century Plant problems by providing your plant with the best possible growing conditions. These succulents perform best when planted in fully sunny areas, although they can handle some light shade. Century Plant grows best in sandy or gritty soils with dry to medium moisture. These drought-tolerant plants only need occasional watering in dry summer weather to remain healthy. Give the plant plenty of room to grow and make sure it is planted away from foot traffic. The sharp spines can poke you and cause your skin to swell painfully.
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文章
Dummer. ゛☀
2017年09月19日
Succulents are hardy plants that add a striking appearance to any garden or home. Performing best in U.S. Department of Agriculture hardiness zones 3 through 9, succulents are good plants for the novice and expert gardener alike, as they require little attention. Because succulents are desert plants, they should be watered sparingly. Succulents are typically not susceptible to insect or pest infestation, but overwatering can lead to root or stem rot, a preventable and easily fixable disease. Succulents with signs of root or stem rot should be treated immediately.
1. Check the plant for infected areas. These typically appear as dark brown to black spots or areas on the low part of the plant. Other signs of root or stem rot include puckered flesh with a dark tint around the infected area.
2. Stop watering a plant with rot. Remove the plant from its pot. Remove the soil mixture and clean out the pot thoroughly to ensure no remnants of the fungus are left.
3. Cut the infected black stem from the plant with a garden knife. Let the healthy portion of the plant dry naturally for several hours, keeping the succulent out of direct sunlight during this process. If other areas of the plant are showing minimal signs of rot, keep an eye on the plant. Succulents can recover from stem rot if properly watered and placed in a warm, dry location.
4. Using the cleaned out pot or a fresh one, combine equal parts soil, coarse sand and peat moss. Don’t reuse any of the materials used with the infected plant.
5. Pour roughly 2 inches (5 cm) of the mixture into the pot. Place the newly doctored succulent into the pot with the roots lying on top of the soil. Fill the pot with the soil mixture until it reaches the base of the stems. Firmly pat the soil around the plant.
6. Place the succulent in a brightly lit spot with warm temperatures. Succulents prefer dry climates, so don’t place the plant in a humid location.
7. Water the plant with just enough water to moisten the soil one week after repotting. After the soil has completely dried out, you can water more thoroughly.
Succulents grow best in well-drained soils that provide a high water-holding capacity. Planting succulents in a clay pot with a drainage hole ensures there is no sitting water and that the soil dries out between waterings. Succulents are dormant during the winter and should only be watered lightly at this time.
1. Check the plant for infected areas. These typically appear as dark brown to black spots or areas on the low part of the plant. Other signs of root or stem rot include puckered flesh with a dark tint around the infected area.
2. Stop watering a plant with rot. Remove the plant from its pot. Remove the soil mixture and clean out the pot thoroughly to ensure no remnants of the fungus are left.
3. Cut the infected black stem from the plant with a garden knife. Let the healthy portion of the plant dry naturally for several hours, keeping the succulent out of direct sunlight during this process. If other areas of the plant are showing minimal signs of rot, keep an eye on the plant. Succulents can recover from stem rot if properly watered and placed in a warm, dry location.
4. Using the cleaned out pot or a fresh one, combine equal parts soil, coarse sand and peat moss. Don’t reuse any of the materials used with the infected plant.
5. Pour roughly 2 inches (5 cm) of the mixture into the pot. Place the newly doctored succulent into the pot with the roots lying on top of the soil. Fill the pot with the soil mixture until it reaches the base of the stems. Firmly pat the soil around the plant.
6. Place the succulent in a brightly lit spot with warm temperatures. Succulents prefer dry climates, so don’t place the plant in a humid location.
7. Water the plant with just enough water to moisten the soil one week after repotting. After the soil has completely dried out, you can water more thoroughly.
Succulents grow best in well-drained soils that provide a high water-holding capacity. Planting succulents in a clay pot with a drainage hole ensures there is no sitting water and that the soil dries out between waterings. Succulents are dormant during the winter and should only be watered lightly at this time.
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文章
Dummer. ゛☀
2017年09月19日
Large, ragged holes in the leaves of cabbage, broccoli, Brussels sprouts, collards, kale, or cauliflower plants are a sign that cabbageworms may have invaded your garden. The green caterpillars may also bore into the heads of these crops, leaving behind their dark green frass (droppings). Cabbage loopers cause similar damage. Plants can tolerate a moderate amount of damage without reduction in yield.
The cabbageworm is the larval form of a small white butterfly (Pieris rapae) that has three to four black spots on its wings. The butterfly lays white eggs on the underside of leaves; eggs hatch within a week and the larvae feed for approximately two weeks. The larvae pupate in silken cocoons attached to the lower leaves. There are several generations per year, and they are found throughout North America.
Prevention and control
Cover susceptible crops with garden fabric in early spring as a barrier to the egg-laying moths.
If plants are not covered, inspect them frequently. Crush the eggs; handpick the cabbageworms and drop them into a pail of soapy water.
Encourage native beneficial insects, such as parasitic wasps, that prey on caterpillars.
Remove plant debris from the garden in fall to minimize opportunities for the pest to overwinter.
The cabbageworm is the larval form of a small white butterfly (Pieris rapae) that has three to four black spots on its wings. The butterfly lays white eggs on the underside of leaves; eggs hatch within a week and the larvae feed for approximately two weeks. The larvae pupate in silken cocoons attached to the lower leaves. There are several generations per year, and they are found throughout North America.
Prevention and control
Cover susceptible crops with garden fabric in early spring as a barrier to the egg-laying moths.
If plants are not covered, inspect them frequently. Crush the eggs; handpick the cabbageworms and drop them into a pail of soapy water.
Encourage native beneficial insects, such as parasitic wasps, that prey on caterpillars.
Remove plant debris from the garden in fall to minimize opportunities for the pest to overwinter.
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文章
Dummer. ゛☀
2017年09月19日
A major agricultural pest, the tomato fruitworm can feed on many different plants. Hence, the species has been given many different common names including cotton bollworm and corn earworm. It has also been known to consume tobacco, legumes, grain sorghum, and other vegetables and fruits.
The pest occurs throughout the Western Hemisphere. In warm areas several generations occur annually. North of Interstate 70 the pupae cannot overwinter in the soil. Most populations enter Missouri as migrating swarms of moths from the southern United States.
Symptoms and Diagnosis
Tomato Fruitworm
The evidence of tomato fruitworm is usually a visible black hole at the base of the fruit stem. When the tomato is cut, tunneling is evident and the cavity may contain frass and decay as well as the worm itself.
Corn Earworm
Most evidence of corn earworm is at the tip of the ear—damaged kernels, frass, the worm itself, and possibly resulting fungal disease.
Life Cycle
The eggs of this pest are each about ½ the diameter of a pinhead. They are spherical with a flattened base and white or cream in color, developing a reddish-brown band just prior to the young hatching. Depending on the temperature, the young hatch in 2-10 days.
The larvae measure 11/2-2 inches when fully grown and may be green, brown, pink, yellow, or even black. They have tan heads and alternating light and dark stripes run lengthwise on the bodies. The skin is coarse and has small, thorn-like projections called tubercles. The larval stage lasts 14-21 days.
When the larvae are finished feeding the worms drop to the ground and enter the soil near the base of the plant where they transform into shiny brown pupae. During summer adults emerge in 10-14 days and start the cycle over. In the fall, south of Interstate 70 the pupae survive winter 2-6 inches below the soil surface. The moths emerge from overwintering pupae during late April and May.
Adult moths are usually light yellow-olive in color with a single dark spot near the center of each forewing. Each forewing has 3 slanted dark bands. Their hind wings are white.
The cycle repeats itself with the moths laying eggs at dusk on host plants on warm days. The total generation time is 28-35 days.
The moths lay eggs on the foliage of the tomato plants. With corn the moths usually lay eggs on corn tassels and silks but the larvae will migrate down the silk to the ear tips within one hour of hatching where they will feed on the developing kernels protected by the husk. When larval development is complete the larvae chew through the husk and drop to the ground to begin the pupal stage.
Integrated Pest Management Strategies
Tomato Fruitworm
1. Sanitation. Collect and dispose of any infested fruit before the insect completes its life cycle.
2. Introduce parasitic wasps. Do not remove parasitized caterpillars. Instead, leave them to assist as a natural, biological control.
3. Dusting with diatomaceous earth may kill larvae.
4. Use of a biological pesticide such as Bt can kill larvae during the warmest months.
5. Use chemical pesticides. The pest has developed a resistance to many pesticides but the following pesticides are often used: esfenvalerate (Asana), methomyl (Lannate), azinphos-methyl (Guthion), carbaryl (Sevin), or pyrethrin. These must be applied before the worm enters the fruit.
6. Minimize local food sources. Avoid planting tomatoes near corn or other hosts of the fruitworm to minimize populations.
The pest occurs throughout the Western Hemisphere. In warm areas several generations occur annually. North of Interstate 70 the pupae cannot overwinter in the soil. Most populations enter Missouri as migrating swarms of moths from the southern United States.
Symptoms and Diagnosis
Tomato Fruitworm
The evidence of tomato fruitworm is usually a visible black hole at the base of the fruit stem. When the tomato is cut, tunneling is evident and the cavity may contain frass and decay as well as the worm itself.
Corn Earworm
Most evidence of corn earworm is at the tip of the ear—damaged kernels, frass, the worm itself, and possibly resulting fungal disease.
Life Cycle
The eggs of this pest are each about ½ the diameter of a pinhead. They are spherical with a flattened base and white or cream in color, developing a reddish-brown band just prior to the young hatching. Depending on the temperature, the young hatch in 2-10 days.
The larvae measure 11/2-2 inches when fully grown and may be green, brown, pink, yellow, or even black. They have tan heads and alternating light and dark stripes run lengthwise on the bodies. The skin is coarse and has small, thorn-like projections called tubercles. The larval stage lasts 14-21 days.
When the larvae are finished feeding the worms drop to the ground and enter the soil near the base of the plant where they transform into shiny brown pupae. During summer adults emerge in 10-14 days and start the cycle over. In the fall, south of Interstate 70 the pupae survive winter 2-6 inches below the soil surface. The moths emerge from overwintering pupae during late April and May.
Adult moths are usually light yellow-olive in color with a single dark spot near the center of each forewing. Each forewing has 3 slanted dark bands. Their hind wings are white.
The cycle repeats itself with the moths laying eggs at dusk on host plants on warm days. The total generation time is 28-35 days.
The moths lay eggs on the foliage of the tomato plants. With corn the moths usually lay eggs on corn tassels and silks but the larvae will migrate down the silk to the ear tips within one hour of hatching where they will feed on the developing kernels protected by the husk. When larval development is complete the larvae chew through the husk and drop to the ground to begin the pupal stage.
Integrated Pest Management Strategies
Tomato Fruitworm
1. Sanitation. Collect and dispose of any infested fruit before the insect completes its life cycle.
2. Introduce parasitic wasps. Do not remove parasitized caterpillars. Instead, leave them to assist as a natural, biological control.
3. Dusting with diatomaceous earth may kill larvae.
4. Use of a biological pesticide such as Bt can kill larvae during the warmest months.
5. Use chemical pesticides. The pest has developed a resistance to many pesticides but the following pesticides are often used: esfenvalerate (Asana), methomyl (Lannate), azinphos-methyl (Guthion), carbaryl (Sevin), or pyrethrin. These must be applied before the worm enters the fruit.
6. Minimize local food sources. Avoid planting tomatoes near corn or other hosts of the fruitworm to minimize populations.
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文章
Dummer. ゛☀
2017年09月19日
Viral infections can reduce plant vigor by disrupting cellular functioning, but do not commonly kill plants. Tobacco mosaic is one of the most highly persistent tomato diseases because it can remain viable without a host for many years and it is able to withstand high heat. The virus is spread primarily by mechanical methods. Gardeners can contaminate their hands when they touch tobacco products or infected plants and weeds and spread the virus to healthy plants.
Symptoms and Diagnosis
Tobacco mosaic virus is not as distinct as other viruses, but yellow-green mottling on leaves is the most characteristic symptom of the disease. Infected plants have stunted growth, and flowers and leaflets may be curled, distorted, and smaller than normal in size. Open blooms may have brown streaks through them. Yellow, chlorotic spotting is characteristic of pepper plants that are infected.
Life Cycle
Tobacco mosaic virus survives on infected seeds, plant debris, and even clothing for months or years. The virus enters plants through wounds sustained in transplanting or pruning. It spreads rapidly once it is in the host. The virus can remain viable for years on dried plant debris and is extremely tolerant of very high temperatures. Tobacco products are the most common source of inoculum; smokers can infect plants by handling them. The virus is not spread by aphids.
Integrated Pest Management Strategies
1. Remove and destroy infected plants. Pull plants with mosaic symptoms immediately. Remove the debris from the garden area and bury them if possible.
2. Keep your garden weed-free. Some weed may be harboring the virus. These represent sources of inoculum.
3. Always wash your hands thoroughly and disinfect tools. Before handling plants, wash with soap and water, especially if you're a smoker.
4. Plant resistant varieties of tomato. Suggested varieties include: ‘Big Pick’, ‘Celebrity’, ‘President’, and ‘Park's Extra Early Hybrid’. Other resistant varieties will be labeled TMV resistant.
Symptoms and Diagnosis
Tobacco mosaic virus is not as distinct as other viruses, but yellow-green mottling on leaves is the most characteristic symptom of the disease. Infected plants have stunted growth, and flowers and leaflets may be curled, distorted, and smaller than normal in size. Open blooms may have brown streaks through them. Yellow, chlorotic spotting is characteristic of pepper plants that are infected.
Life Cycle
Tobacco mosaic virus survives on infected seeds, plant debris, and even clothing for months or years. The virus enters plants through wounds sustained in transplanting or pruning. It spreads rapidly once it is in the host. The virus can remain viable for years on dried plant debris and is extremely tolerant of very high temperatures. Tobacco products are the most common source of inoculum; smokers can infect plants by handling them. The virus is not spread by aphids.
Integrated Pest Management Strategies
1. Remove and destroy infected plants. Pull plants with mosaic symptoms immediately. Remove the debris from the garden area and bury them if possible.
2. Keep your garden weed-free. Some weed may be harboring the virus. These represent sources of inoculum.
3. Always wash your hands thoroughly and disinfect tools. Before handling plants, wash with soap and water, especially if you're a smoker.
4. Plant resistant varieties of tomato. Suggested varieties include: ‘Big Pick’, ‘Celebrity’, ‘President’, and ‘Park's Extra Early Hybrid’. Other resistant varieties will be labeled TMV resistant.
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文章
Dummer. ゛☀
2017年09月19日
A strain of the fungus, Phytophthora infestans, causes late blight in tomatoes. As the common name implies, Phytophthora is prevalent on tomato hosts in late summer, after the plants have bloomed. Late blight is more common in north central and northeastern states, but is observed in the Midwest when the humidity is high and temperatures are around 68 degrees F late in the growing season. Watch for the disease when cool, moist nights are followed by warm, humid days.
Symptoms and Diagnosis
One of the first symptoms of late blight is watersoaked patches on older leaves. Late blight attacks the older leaves first, then spreads to the fruit. Green-black watery patches develop on the upper surfaces of older leaves. These patches will enlarge quickly, and in moist weather, a downy growth may develop on the underside of the leaf. On the fruit, you will see rough, firm, dark-colored spots.
Life Cycle
The fungus overwinters on tomato and potato plant debris, including potato tubers. The fungus can produce spores over a broad range of temperatures although spores are most infective at temperatures of 68 degrees F with high humidity. The spores are transmitted by water or are wind blown and may be introduced from diseased plants in nearby gardens. The fungus invades the plant through leaf stomata. Infection rarely occurs when temperatures are higher than 80 degrees F and humidity is less than 90%.
Integrated Pest Management Strategies
1. Plant resistant varieties. Several tomato varieties are designated as resistant to late blight.
2. Avoid overhead watering. Avoid working around plants when they are wet. Both of these practices can spread the fungal spores from plant to plant.
3. Clean up all garden debris in the fall. Remove and destroy any affected plants as soon as they are observed.
4. Practice crop rotation. Do not plant tomatoes, potatoes, and celery in succession. All of these crops are susceptible.
5. Use a copper-based fungicide. Apply when symptoms are first identified. Reapply at 7–10 day intervals.
Symptoms and Diagnosis
One of the first symptoms of late blight is watersoaked patches on older leaves. Late blight attacks the older leaves first, then spreads to the fruit. Green-black watery patches develop on the upper surfaces of older leaves. These patches will enlarge quickly, and in moist weather, a downy growth may develop on the underside of the leaf. On the fruit, you will see rough, firm, dark-colored spots.
Life Cycle
The fungus overwinters on tomato and potato plant debris, including potato tubers. The fungus can produce spores over a broad range of temperatures although spores are most infective at temperatures of 68 degrees F with high humidity. The spores are transmitted by water or are wind blown and may be introduced from diseased plants in nearby gardens. The fungus invades the plant through leaf stomata. Infection rarely occurs when temperatures are higher than 80 degrees F and humidity is less than 90%.
Integrated Pest Management Strategies
1. Plant resistant varieties. Several tomato varieties are designated as resistant to late blight.
2. Avoid overhead watering. Avoid working around plants when they are wet. Both of these practices can spread the fungal spores from plant to plant.
3. Clean up all garden debris in the fall. Remove and destroy any affected plants as soon as they are observed.
4. Practice crop rotation. Do not plant tomatoes, potatoes, and celery in succession. All of these crops are susceptible.
5. Use a copper-based fungicide. Apply when symptoms are first identified. Reapply at 7–10 day intervals.
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文章
Dummer. ゛☀
2017年09月19日
If your tomato plants yellow and wilt on one side of the plant or one side of a leaf, they may have Fusarium wilt. Fusarium wilt on tomatoes is caused by Fusarium oxysporumsp. lycopersici. It is a soilborn fungus that is found throughout the United States, especially in warm regions of the country. The organism is specific for tomato and is very longlived in all regions of the United States. The disease develops more quickly in soils that are high in nitrogen and low in potassium. In addition, plants grown in sandy soils tend to contract this disease more often.
Symptoms and Diagnosis
Fusarium often causes yellowing on one side of the plant or leaf. Yellowing begins with the older, bottom leaves, followed by wilting, browning, and defoliation. Growth is typically stunted, and little or no fruit develops. Brown, vascular tissue can be found when the infected stem is cut at its base. Infected plants often die before maturing.
Life Cycle
Fusarium fungi survive in the soil or associated with plant debris for up to ten years. Disease development is favored by warm soil temperatures, and symptoms are most prevalent when temperatures range from 80–90 degrees F. The fungi enter the plants through their roots and are then spread throughout the plant by the plant's water-conducting vessels.
Integrated Pest Management Strategies
1. Plant resistant varieties. These varieties are labeled VF and include cultivars such as ‘Spring Giant’, ‘Burpee VF’, ‘Supersonic’, ‘Celebrity’, ‘Manalucie’, ‘Better Boy’, and ‘Small Fry’.
2. Remove infected plants from the garden. Removal of infected plants will help limit the disease's spread. Soil sterilization or fumigation will eliminate wilt fungi from the soil but are impractical for home gardeners. Soil replacement should be considered.
3. Avoid over-application of high nitrogen fertilizers. High soil nitrogen levels accompanied by low potassium levels can increase susceptibility to the fungus. Use a soil test to determine potassium levels and other nutrient deficiencies.
4. Avoid activity in wet plantings. Movement of wet soil from place to place via shoes or tools will spread the disease.
5. Sanitize stakes and tomato cages at the end of the season. Avoid using soil-encrusted tools and supports season after season. A thorough cleaning with water will reduce most risk of transmitting the disease.
6. For four years, do not plant solanaceous plants in the area where infection occurred. Tomato, potato, pepper, and eggplant are all susceptible to the disease and may allow its survival year after year in the same planting area.
Symptoms and Diagnosis
Fusarium often causes yellowing on one side of the plant or leaf. Yellowing begins with the older, bottom leaves, followed by wilting, browning, and defoliation. Growth is typically stunted, and little or no fruit develops. Brown, vascular tissue can be found when the infected stem is cut at its base. Infected plants often die before maturing.
Life Cycle
Fusarium fungi survive in the soil or associated with plant debris for up to ten years. Disease development is favored by warm soil temperatures, and symptoms are most prevalent when temperatures range from 80–90 degrees F. The fungi enter the plants through their roots and are then spread throughout the plant by the plant's water-conducting vessels.
Integrated Pest Management Strategies
1. Plant resistant varieties. These varieties are labeled VF and include cultivars such as ‘Spring Giant’, ‘Burpee VF’, ‘Supersonic’, ‘Celebrity’, ‘Manalucie’, ‘Better Boy’, and ‘Small Fry’.
2. Remove infected plants from the garden. Removal of infected plants will help limit the disease's spread. Soil sterilization or fumigation will eliminate wilt fungi from the soil but are impractical for home gardeners. Soil replacement should be considered.
3. Avoid over-application of high nitrogen fertilizers. High soil nitrogen levels accompanied by low potassium levels can increase susceptibility to the fungus. Use a soil test to determine potassium levels and other nutrient deficiencies.
4. Avoid activity in wet plantings. Movement of wet soil from place to place via shoes or tools will spread the disease.
5. Sanitize stakes and tomato cages at the end of the season. Avoid using soil-encrusted tools and supports season after season. A thorough cleaning with water will reduce most risk of transmitting the disease.
6. For four years, do not plant solanaceous plants in the area where infection occurred. Tomato, potato, pepper, and eggplant are all susceptible to the disease and may allow its survival year after year in the same planting area.
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Dummer. ゛☀
2017年09月19日
Early blight is a fungal disease, Alternaria sp., that occurs on tomatoes throughout North America. Early blight can affect seedlings but is generally observed on older plants and is especially severe on plants of poor vigor. Plants infected with the fungus can display collar rust on the stems, infected older leaves, and fruits that crack at the stem. Infection on leaves is the most common symptom.
Symptoms and Diagnosis
The appearance of circular or irregular dark spots on the lower, more mature leaves is one of the first symptoms of infection. Eventually, the spots enlarge into a series of concentric rings surrounded by a yellow area. The entire leaf may be killed and will drop off the plant. Early blight can result in extensive defoliation, exposing fruit to sunscald and reducing yields. This disease typically progresses from the base of the plant, upward.
Life Cycle
Early blight spores survive on old plant debris or in the soil. Spores are spread by wind and rain, but occasionally, flea beetles transmit this disease. Fungal spores enter a host through wounds in the plant cuticle. Spores thrive in moist, warm temperatures (80–90 degrees F) and can persist in partially decomposed garden waste for at least a year.
Integrated Pest Management Strategies
1. Plant resistant varieties. Varieties such as ‘Early Cascade’, ‘Floramerica’, ‘Jetstar’, ‘Manlucie’, ‘Supersonic’, and ‘Surecrop’ have some tolerance to early blight. These varieties will require a less intensive management program than susceptible varieties.
2. Maintain plant vigor. Stressed plants are more susceptible to early blight. Water the plants regularly, but don't fertilize until the plants are well-established and in full blossom. Do not mulch until the soil is warm.
3. Do a thorough cleanup of the garden in the fall. Remove plant debris or till it into the soil. Pull weeds that compete for light, water, and nutrients, especially nightshade, horse nettle, and other weeds in the tomato family.
4. Rotate crops. Practice a 2- or 3-year crop rotation. Avoid planting eggplant or potatoes where tomatoes were last planted.
5. Avoid activity when plants are wet. Confine staking and picking to times when foliage is dry. Disease is more readily spread when plant foliage is wet.
6. Protect clean foliage with a fungicide. Effective fungicides include copper (Kocide), chlorothalonil (Bravo, Daconil), mancozeb, or maneb. Apply at fruit set and reapply every 7–14 days.
Symptoms and Diagnosis
The appearance of circular or irregular dark spots on the lower, more mature leaves is one of the first symptoms of infection. Eventually, the spots enlarge into a series of concentric rings surrounded by a yellow area. The entire leaf may be killed and will drop off the plant. Early blight can result in extensive defoliation, exposing fruit to sunscald and reducing yields. This disease typically progresses from the base of the plant, upward.
Life Cycle
Early blight spores survive on old plant debris or in the soil. Spores are spread by wind and rain, but occasionally, flea beetles transmit this disease. Fungal spores enter a host through wounds in the plant cuticle. Spores thrive in moist, warm temperatures (80–90 degrees F) and can persist in partially decomposed garden waste for at least a year.
Integrated Pest Management Strategies
1. Plant resistant varieties. Varieties such as ‘Early Cascade’, ‘Floramerica’, ‘Jetstar’, ‘Manlucie’, ‘Supersonic’, and ‘Surecrop’ have some tolerance to early blight. These varieties will require a less intensive management program than susceptible varieties.
2. Maintain plant vigor. Stressed plants are more susceptible to early blight. Water the plants regularly, but don't fertilize until the plants are well-established and in full blossom. Do not mulch until the soil is warm.
3. Do a thorough cleanup of the garden in the fall. Remove plant debris or till it into the soil. Pull weeds that compete for light, water, and nutrients, especially nightshade, horse nettle, and other weeds in the tomato family.
4. Rotate crops. Practice a 2- or 3-year crop rotation. Avoid planting eggplant or potatoes where tomatoes were last planted.
5. Avoid activity when plants are wet. Confine staking and picking to times when foliage is dry. Disease is more readily spread when plant foliage is wet.
6. Protect clean foliage with a fungicide. Effective fungicides include copper (Kocide), chlorothalonil (Bravo, Daconil), mancozeb, or maneb. Apply at fruit set and reapply every 7–14 days.
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Dummer. ゛☀
2017年09月19日
Clubroot is a fungal disease that affects a number of plants in the cabbage family including cabbages, radish, mustard and ornamentals such as candytuft. It is caused by the fungus Plasmodiophora brassicae and gets its name from the club-like roots it induces in infected plants. Its diagnosis is often missed as the infected plant part, the roots, are underground and out of sight.
Symptoms and Diagnosis
The first symptom is usually wilting during average daily conditions but recovery at night. The older leaves may yellow and die and the plants look stunted. Examination of the root system reveals enlarged roots that make them look club-like and reduced feeder roots. The reduction in feeder roots as well as disruption of the water conducting tissue in the roots causes the drought-like symptoms. Development of the disease if favored by a low soil pH (below 7.0), cool soil, and excess soil moisture. The organism can survive in the soil for over 10 years. Since most soils in the St. Louis area are above a pH of 7 the disease is rare in our area.
Life Cycle
Clubroot is a soil-borne fungus that infects plants through root hairs by zoospores. After infection the roots enlarge and many spores are produced in the swollen roots. The mobile zoospores can re-infect other roots on the plant or nearby plants. Late in the season resting spores are produced. When roots die and decay the resting spores are released into the soil where they can survive for many years and be transported through the soil by water movement and garden equipment.
Integrated Pest Management Strategies
1. Remove diseased plants. The disease organism can reside in the soil for many years so although quick removal of diseased plants is recommended the disease may return if plants in the cabbage family are planted in the infested soil the following year. Also remove any cabbage family weeds such as wild mustard, which can harbor the disease.
2. Add lime. Since problems are more severe in acid soils (pH 5.0-7.0) adding lime to acid soils can help control the disease.
3. Rotate crops Rotate where you grow cabbage, radishes, mustards, etc in your garden. Wait 5-6 years before replanting in an area.
Symptoms and Diagnosis
The first symptom is usually wilting during average daily conditions but recovery at night. The older leaves may yellow and die and the plants look stunted. Examination of the root system reveals enlarged roots that make them look club-like and reduced feeder roots. The reduction in feeder roots as well as disruption of the water conducting tissue in the roots causes the drought-like symptoms. Development of the disease if favored by a low soil pH (below 7.0), cool soil, and excess soil moisture. The organism can survive in the soil for over 10 years. Since most soils in the St. Louis area are above a pH of 7 the disease is rare in our area.
Life Cycle
Clubroot is a soil-borne fungus that infects plants through root hairs by zoospores. After infection the roots enlarge and many spores are produced in the swollen roots. The mobile zoospores can re-infect other roots on the plant or nearby plants. Late in the season resting spores are produced. When roots die and decay the resting spores are released into the soil where they can survive for many years and be transported through the soil by water movement and garden equipment.
Integrated Pest Management Strategies
1. Remove diseased plants. The disease organism can reside in the soil for many years so although quick removal of diseased plants is recommended the disease may return if plants in the cabbage family are planted in the infested soil the following year. Also remove any cabbage family weeds such as wild mustard, which can harbor the disease.
2. Add lime. Since problems are more severe in acid soils (pH 5.0-7.0) adding lime to acid soils can help control the disease.
3. Rotate crops Rotate where you grow cabbage, radishes, mustards, etc in your garden. Wait 5-6 years before replanting in an area.
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Dummer. ゛☀
2017年09月19日
Rose rosette disease, also known as witches’-broom of rose, is caused by a virus (Emaravirus sp.) that is spread by a very small, eriophyid mite. The disease is limited to plants in the genus Rosa but R. setigera, R. aricularis, R. arkansana, R. blanda, R. palustris, R. carolina and R. spinosissima are believed to be resistant. Its main host is the multiflora rose, which is considered a noxious weed throughout much of the United States. Interest in rose rosette has been generated by the threat to garden roses and its possible use as a biocontrol for multiflora rose.
Symptoms and Diagnosis
The earliest symptoms of rose rosette disease include a red pigmentation of the underside of leaf veins followed by sharply increased growth of vegetative shoots, which are typically more succulent than normal and colored in various shades of red. Leaves often become deformed, crinkled, and brittle with yellow mosaics and red pigmentation. As the disease progresses, leaves become very small, petioles are shortened, and most lateral buds grow, producing short, intensely red shoots. The disease causes the plant to be exceptionally susceptible to freeze damage. Symptoms on cultivated roses are typically less severe than on multiflora rose. Cultivated roses show symptoms of thickened, succulent stems and a proliferation of thorns. Symptoms can mimic some forms of herbicide damage.
Life Cycle
The disease is transmitted by an eriophyid mite, a wingless mite that can travel passively in the wind as well as on contaminated clothing and equipment. The mites are most prevalent in the apex of the rose shoots where they feed and reproduce. Females overwinter under bark or on bud scales of living roses. The females move to newly developing shoots where they lay one egg a day for about 30 days. The young hatch in 3-4 days. They can reach adulthood in about a week depending upon temperatures. Multiple generations occur each year until fall when females seek overwintering sites. The mites are hampered by low humidity and can only survive about 8 hours without being on a host plant.
Virus transmission occurs most readily between the months of May through mid-July when plants are making active growth. Symptoms from new infections usually start appearing in mid-July. In general, smaller plants go through the disease stages more quickly than larger plants. Small plants are usually killed in about 2 years, while a large plant may survive for five years in a deteriorated condition.
Integrated Pest Management Strategies
1. Remove ornamental roses with symptoms. The entire plant including the roots should be removed and destroyed by burning or placing in a plastic bag. Care must be taken when working with diseased plants as you can facilitate spread of the mites that spreads the disease. Bag the plant before removal, cut it at ground level and then dig out the plant’s roots. Soil need not be removed. Clean tools and put on fresh clothing before moving to a disease-free plant or area.
2. Plant ornamental roses as far away as possible from known stands of multiflora rose. The general recommendation is maintain at least 300 feet between your roses and any stands of multiflora rose. Even greater distance is preferred especially if they are upwind of your desirable rose plants.
3. Control the disease by controlling the mite. Start mite control early by pruning your roses hard in late winter (back by 2/3) to remove as many overwintering mites as possible and then spray with horticultural oil to kill any remaining mites. Organic pesticides such as horticultural oils and insecticidal soap are recommended over other pesticides as these organic pesticides are less harmful to natural predators that feed on the problem mites. Apply weekly during the months of June and July paying particular attention to the new growing tips where the mites will congregate. Refrain from using leaf blowers around roses as they can spread mites.
4. Help to isolate your roses. Do not plant roses too close together. With extra space between the plants mite movement can be reduced. Also, consider interplanting roses with other ornamental plants.
5. Using rose rosette disease as an IPM strategy. The multiflora rose is an exotic invasive species that is responsible for the degradation of millions of acres of farmland and recreational areas. Using the disease to control this invasive weed can cut costs and be considered environmentally friendly for reducing the amount of synthetic chemicals used. However, the disease also affects cultivated roses. One should be extremely cautious and good neighbor-minded when it comes to rose rosette disease.
6. Plant a resistant cultivar. Rose breeders have been working to develop new rose cultivars that are resistant to rose rosette. The first, 'Top Gun', is a shrub rose that is scheduled to be released in 2018. 'Top Gun' is also reportedly resistant to most other common rose diseases. Others cultivars are planned to follow.
Symptoms and Diagnosis
The earliest symptoms of rose rosette disease include a red pigmentation of the underside of leaf veins followed by sharply increased growth of vegetative shoots, which are typically more succulent than normal and colored in various shades of red. Leaves often become deformed, crinkled, and brittle with yellow mosaics and red pigmentation. As the disease progresses, leaves become very small, petioles are shortened, and most lateral buds grow, producing short, intensely red shoots. The disease causes the plant to be exceptionally susceptible to freeze damage. Symptoms on cultivated roses are typically less severe than on multiflora rose. Cultivated roses show symptoms of thickened, succulent stems and a proliferation of thorns. Symptoms can mimic some forms of herbicide damage.
Life Cycle
The disease is transmitted by an eriophyid mite, a wingless mite that can travel passively in the wind as well as on contaminated clothing and equipment. The mites are most prevalent in the apex of the rose shoots where they feed and reproduce. Females overwinter under bark or on bud scales of living roses. The females move to newly developing shoots where they lay one egg a day for about 30 days. The young hatch in 3-4 days. They can reach adulthood in about a week depending upon temperatures. Multiple generations occur each year until fall when females seek overwintering sites. The mites are hampered by low humidity and can only survive about 8 hours without being on a host plant.
Virus transmission occurs most readily between the months of May through mid-July when plants are making active growth. Symptoms from new infections usually start appearing in mid-July. In general, smaller plants go through the disease stages more quickly than larger plants. Small plants are usually killed in about 2 years, while a large plant may survive for five years in a deteriorated condition.
Integrated Pest Management Strategies
1. Remove ornamental roses with symptoms. The entire plant including the roots should be removed and destroyed by burning or placing in a plastic bag. Care must be taken when working with diseased plants as you can facilitate spread of the mites that spreads the disease. Bag the plant before removal, cut it at ground level and then dig out the plant’s roots. Soil need not be removed. Clean tools and put on fresh clothing before moving to a disease-free plant or area.
2. Plant ornamental roses as far away as possible from known stands of multiflora rose. The general recommendation is maintain at least 300 feet between your roses and any stands of multiflora rose. Even greater distance is preferred especially if they are upwind of your desirable rose plants.
3. Control the disease by controlling the mite. Start mite control early by pruning your roses hard in late winter (back by 2/3) to remove as many overwintering mites as possible and then spray with horticultural oil to kill any remaining mites. Organic pesticides such as horticultural oils and insecticidal soap are recommended over other pesticides as these organic pesticides are less harmful to natural predators that feed on the problem mites. Apply weekly during the months of June and July paying particular attention to the new growing tips where the mites will congregate. Refrain from using leaf blowers around roses as they can spread mites.
4. Help to isolate your roses. Do not plant roses too close together. With extra space between the plants mite movement can be reduced. Also, consider interplanting roses with other ornamental plants.
5. Using rose rosette disease as an IPM strategy. The multiflora rose is an exotic invasive species that is responsible for the degradation of millions of acres of farmland and recreational areas. Using the disease to control this invasive weed can cut costs and be considered environmentally friendly for reducing the amount of synthetic chemicals used. However, the disease also affects cultivated roses. One should be extremely cautious and good neighbor-minded when it comes to rose rosette disease.
6. Plant a resistant cultivar. Rose breeders have been working to develop new rose cultivars that are resistant to rose rosette. The first, 'Top Gun', is a shrub rose that is scheduled to be released in 2018. 'Top Gun' is also reportedly resistant to most other common rose diseases. Others cultivars are planned to follow.
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Dummer. ゛☀
2017年09月19日
Most plants growing in average garden soil in the St. Louis area receive sufficient nutrients from the soil that deficiencies are not a problem. The most notable exception is iron chlorosis of trees and shrubs, which is more likely to result from a high soil pH than a lack of iron in the soil. See below for more information on this deficiency. Also, because of the higher nitrogen requirement of turf grasses and leafy vegetables in the vegetable garden they may benefit from some additional nitrogen fertilizer. Also, nutrient deficiencies are likely to occur in plants growing in containers that are not fertilized regularly because of the reduced soil volume and the lower nutrient holding capacity of soil-less mixes used for container plants.
Following is some brief information on the symptoms of common nutrient deficiencies:
Macronutrients
Nitrogen
Lack of nitrogen shows up as overall yellow-green leaves instead of a dark green, yellowing and dropping of lower leaves (can be caused by many factors), and overall reduced plant size and slow growth. Although most garden plants receive adequate nitrogen from the soil and dissolved in rainwater, applying nitrogen in a complete, balanced fertilizer such as 20-20-20 once a year around perennials and shrubs is usually sufficient to provide adequate growth. Leafy vegetables can benefit from additional nitrogen. Most trees do not suffer from lack of sufficient nitrogen. Although lawns respond quickly and dramatically to the application of nitrogen, becoming green and lush, its use should be tempered, as this lush growth is also more susceptible to attack by insects and disease. Nitrogen in best applied to cool-season grasses in fall and on warm season grasses as they begin to grow in early summer. Nitrogen should be applied to container plants in a complete fertilizer, such as 20-20-20.
Phosphorus
Lack of phosphorus typically results in reduced growth and in some plants purplish foliage, especially older leaves. Although it may be observed on container grown plants most soils in Missouri contain ample phosphorus so more rarely would deficiencies be noticed in a garden situation. If you suspect your plants are showing symptoms of lack of phosphorus, have your soil tested. Then add phosphorus as required by the test results. Container grown plants require regular fertilizing with a complete fertilizer such as 20-20-20.
Potash
Again, lack of potash is rare in Missouri soils but deficiency symptoms typically result in stunted growth. Older leaves may yellow and leaf edges may roll up. If a deficiency is suspected have your soil tested and follow the recommendations provided with your soil test results. Container grown plants require regular fertilizing with a complete fertilizer such as 20-20-20.
Calcium, Magnesium and Sulfur
These three elements complete the macronutrients. They are frequently available in adequate amounts in St. Louis soils.
Micronutrients
Several micronutrients are required for good plant growth. These include: iron, manganese, copper, zinc, boron, chlorine, molybdenum, and nickel. Symptoms are almost entirely crop specific, hence, listing general symptoms of little use. Also, their identification can be difficult from symptoms alone. Some are well known and a plant disease reference of well-studied crops may show pictures of the classic symptoms of a particular nutrient deficiency on a crop. Frequently, however, short of sending leaf tissue off to a lab for analysis the gardener is left questioning whether the symptoms they are seeing are caused by a nutrient deficiency or not. If in doubt, treat the plant with a micronutrient fertilizer or a complete fertilizer containing micronutrients. Since most micronutrients are used in very small amounts the fertilizer will provide the plant what it needs if the soil is indeed lacking in a micronutrient. Follow the product’s label directions. In the St. Louis area the most commonly encountered micronutrient problem is with iron.
Iron
Lack of iron most notably causes what is referred to as iron chlorosis or yellowing leaves where the veins remain green. New growth is most affected. Lack of iron in the soil, a high soil pH (over 7) that restricts availability of iron in the soil, and environmental conditions can all result in iron chlorosis. For detailed information on iron chlorosis see the IPM page “Iron Chlorosis of Trees and Shrubs” herein. Potted plants showing iron chlorosis can be watered with a fertilizer containing iron or a specific iron fertilizer such as chelated iron.
Following is some brief information on the symptoms of common nutrient deficiencies:
Macronutrients
Nitrogen
Lack of nitrogen shows up as overall yellow-green leaves instead of a dark green, yellowing and dropping of lower leaves (can be caused by many factors), and overall reduced plant size and slow growth. Although most garden plants receive adequate nitrogen from the soil and dissolved in rainwater, applying nitrogen in a complete, balanced fertilizer such as 20-20-20 once a year around perennials and shrubs is usually sufficient to provide adequate growth. Leafy vegetables can benefit from additional nitrogen. Most trees do not suffer from lack of sufficient nitrogen. Although lawns respond quickly and dramatically to the application of nitrogen, becoming green and lush, its use should be tempered, as this lush growth is also more susceptible to attack by insects and disease. Nitrogen in best applied to cool-season grasses in fall and on warm season grasses as they begin to grow in early summer. Nitrogen should be applied to container plants in a complete fertilizer, such as 20-20-20.
Phosphorus
Lack of phosphorus typically results in reduced growth and in some plants purplish foliage, especially older leaves. Although it may be observed on container grown plants most soils in Missouri contain ample phosphorus so more rarely would deficiencies be noticed in a garden situation. If you suspect your plants are showing symptoms of lack of phosphorus, have your soil tested. Then add phosphorus as required by the test results. Container grown plants require regular fertilizing with a complete fertilizer such as 20-20-20.
Potash
Again, lack of potash is rare in Missouri soils but deficiency symptoms typically result in stunted growth. Older leaves may yellow and leaf edges may roll up. If a deficiency is suspected have your soil tested and follow the recommendations provided with your soil test results. Container grown plants require regular fertilizing with a complete fertilizer such as 20-20-20.
Calcium, Magnesium and Sulfur
These three elements complete the macronutrients. They are frequently available in adequate amounts in St. Louis soils.
Micronutrients
Several micronutrients are required for good plant growth. These include: iron, manganese, copper, zinc, boron, chlorine, molybdenum, and nickel. Symptoms are almost entirely crop specific, hence, listing general symptoms of little use. Also, their identification can be difficult from symptoms alone. Some are well known and a plant disease reference of well-studied crops may show pictures of the classic symptoms of a particular nutrient deficiency on a crop. Frequently, however, short of sending leaf tissue off to a lab for analysis the gardener is left questioning whether the symptoms they are seeing are caused by a nutrient deficiency or not. If in doubt, treat the plant with a micronutrient fertilizer or a complete fertilizer containing micronutrients. Since most micronutrients are used in very small amounts the fertilizer will provide the plant what it needs if the soil is indeed lacking in a micronutrient. Follow the product’s label directions. In the St. Louis area the most commonly encountered micronutrient problem is with iron.
Iron
Lack of iron most notably causes what is referred to as iron chlorosis or yellowing leaves where the veins remain green. New growth is most affected. Lack of iron in the soil, a high soil pH (over 7) that restricts availability of iron in the soil, and environmental conditions can all result in iron chlorosis. For detailed information on iron chlorosis see the IPM page “Iron Chlorosis of Trees and Shrubs” herein. Potted plants showing iron chlorosis can be watered with a fertilizer containing iron or a specific iron fertilizer such as chelated iron.
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Dummer. ゛☀
2017年09月19日
Algal leaf spot is a foliar disease most commonly seen in warm humid climates or in greenhouses. The causal organism is Cephaleuros virescens, a green parasitic alga whose usual hosts are plants with leathery leaves such as cotoneasters, magnolias, hollies, rhododendrons and viburnums. Algal leaf spot is sometimes called green scurf because the spots may have a crusty, fuzzy or flaky appearance.
Symptoms and Diagnosis
Algal leaf spot is characterized by grayish, green, brown or orange cushion-like blotches on the leaf surface. Some hosts may also have diseased twigs and branches that are girdled and stunted with reddish brown fruiting bodies. The spots are generally 1/2 inch or less in diameter although they may coalesce to form larger colonies. Leaf tissue may die beneath the spots and the leaves may yellow and drop prematurely.
Life Cycle
During wet weather, the algae produce spores that are spread by wind and splashing rain. The spores infect leaf tissue causing small, greenish circular spots that may age to light brown or reddish brown. The spots may appear raised and velvety. The algae will overwinter or survive other unfavorable environmental conditions in leaf spots including those on fallen leaves.
Integrated Pest Management Strategies
1. Encourage healthy plants with good cultural techniques. This disease is most damaging on plants that are already slow-growing or weakened.
2. Clean up fallen leaves and remove diseased leaves from the plant. Good sanitation practices will help control this disease.
3. Promote dry leaves by improving air circulation and drainage. If necessary, selectively prune overcrowded vegetation. Avoid spraying water on the leaves.
4. Use fungicidal sprays containing copper if chemical control is necessary
Symptoms and Diagnosis
Algal leaf spot is characterized by grayish, green, brown or orange cushion-like blotches on the leaf surface. Some hosts may also have diseased twigs and branches that are girdled and stunted with reddish brown fruiting bodies. The spots are generally 1/2 inch or less in diameter although they may coalesce to form larger colonies. Leaf tissue may die beneath the spots and the leaves may yellow and drop prematurely.
Life Cycle
During wet weather, the algae produce spores that are spread by wind and splashing rain. The spores infect leaf tissue causing small, greenish circular spots that may age to light brown or reddish brown. The spots may appear raised and velvety. The algae will overwinter or survive other unfavorable environmental conditions in leaf spots including those on fallen leaves.
Integrated Pest Management Strategies
1. Encourage healthy plants with good cultural techniques. This disease is most damaging on plants that are already slow-growing or weakened.
2. Clean up fallen leaves and remove diseased leaves from the plant. Good sanitation practices will help control this disease.
3. Promote dry leaves by improving air circulation and drainage. If necessary, selectively prune overcrowded vegetation. Avoid spraying water on the leaves.
4. Use fungicidal sprays containing copper if chemical control is necessary
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Dummer. ゛☀
2017年09月19日
Root weevils feed on a variety of plants, including needled and broad-leaved evergreens, deciduous and herbaceous plants, and several important food crops. Adults feed on leaves of the host plant and larvae feed on the roots. Host plants differ, but similarities in habits, life cycles, and management practices permit them to be addressed as a group.
Representative root weevil species:
Black vine weevil (Otiorhynchus sulcatus) syn: taxus weevil. Host plants: yews, hemlocks, rhododendrons, several other broad-leaved evergreens, and greenhouse plants such as asters, cyclamens, and impatiens. (see IPM sheet: Black Vine Weevil)
Carrot weevil (Listronatus oregonensis) Host plants: carrots and other vegetables. More common in the east.
Strawberry root weevil (Otiorhynchus ovatus) Host plant: strawberries.
New York weevil (Ithycerus noveboracensis) Eastern U.S., west to Nebraska and Texas. Host plants: Hickory, oak, beech.
Sweet potato weevil (Cylas formicarius elegantulus) syn: sweet potato root borer. Introduced species occurring more commonly in the south U.S. Host plant: sweet potato. Probably not here yet, but with global warming, it's probably only a matter of time.
Symptoms and Diagnosis
Starting in spring, emerging root weevil adults feed on the leaves of host plants, notching the leaf edges quite distinctively. The adult weevils rest during the day and feed on the leaf margins after sundown. Conifer needle damage is less evident than that on broad leafed plants. Needles may be severed and dropped from the tree. Adults feeding on new growth may result in sparse foliage.
Although top feeding of the adults is the most conspicuous damage, root feeding of the larvae does the most damage as they chew and girdle roots of their various host plants. Root weevil larvae can be devastating to conifer seedlings. Woody plant seedlings and propagation cuttings are at risk from both root and top feeding. Injured plants may develop a greenish-yellow cast that does not respond to fertilization and watering. Container grown plants may be severely stunted or killed. Injured plants may die suddenly.
Carrots and sweet potatoes affected by root feeders are not commercially viable and mostly not fit for the table. Damage to roots and crowns can weaken, stunt, and kill strawberry plants.
Life Cycle
Outdoors, there is one weevil generation per year. Greenhouse conditions may permit two generations annually. Many, if not most, root weevils dispense with the annoyance and inconvenience of males, producing the eggs of the next generation by means of parthenogenensis. Females deposit eggs in soil and debris near the host plant, starting usually in mid-summer, and continuing well into the fall, laying hundreds of eggs. Eggs hatch in about 10 days and the larvae move into the soil, feeding on root hairs and roots. Older larvae may girdle entire stems. Larvae are legless, c-shaped, and cream colored with brown heads. They spend the winter in the soil and continue their development in the spring as the soil warms. This second feeding period is the most destructive. Later in the spring, the mature larvae pupate in the soil and soon emerge as adult weevils. After several weeks of feeding on the leaves of host plants, adults begin the egg laying cycle again. Some adult weevils will not expire in the fall but will over-winter. These over-wintering adults will begin egg laying earlier than those adults just emerging from the pupae state.
Integrated Pest Management Strategies
(Control efforts may be directed towards both larvae and adults.)
1. Use nematodes can be applied as a soil drench to control root weevil larvae. Two commercially available cultures, Steinernema and Heterorhabditis are effective. Timing is critical. Apply nematodes when soil temperature is 55°F and soil is moist. Pull back any mulch, apply the nematodes and replace the mulch.
2. Apply pesticides. Chemical stomach poisons applied to the foliage are effective. Pesticides registered for use include acephate (Orthene), azadirachtin (Bio-Neem), imidacloprid (Merit), cyfluthrin and endosulfan (Thiodan). Pesticides should be applied to the foliage thoroughly, allowing excess to run off into the soil beneath the plant. Repeat at least twice at two week intervals. Pesticides appropriate for ornamentals may not be safe for vegetable and fruit crops. Read and follow the label instructions on all pesticides.
3. Use sticky substances. Adult weevils emerge from soil and debris at night and climb the plants to eat. Lower trunks of host plants may be wrapped with a four inch band of masking tape and the product Tanglewood applied to the taped surface. Check for buildup of dead insects regularly, and refresh as needed.
4. Try an organic solution. Weevils are attracted to water and may be trapped in shallow pans inset into the soil near affected host plants. Products that contain the organically derived insecticide spinosad are also labeled for leaf-feeding beetles on a wide variety of plants, and may be worth a try. Diatomaceous earth dusted at the base of affected plants is useful. In serious infestations, the lower sides of stems and leaf undersides should also be dusted.
Representative root weevil species:
Black vine weevil (Otiorhynchus sulcatus) syn: taxus weevil. Host plants: yews, hemlocks, rhododendrons, several other broad-leaved evergreens, and greenhouse plants such as asters, cyclamens, and impatiens. (see IPM sheet: Black Vine Weevil)
Carrot weevil (Listronatus oregonensis) Host plants: carrots and other vegetables. More common in the east.
Strawberry root weevil (Otiorhynchus ovatus) Host plant: strawberries.
New York weevil (Ithycerus noveboracensis) Eastern U.S., west to Nebraska and Texas. Host plants: Hickory, oak, beech.
Sweet potato weevil (Cylas formicarius elegantulus) syn: sweet potato root borer. Introduced species occurring more commonly in the south U.S. Host plant: sweet potato. Probably not here yet, but with global warming, it's probably only a matter of time.
Symptoms and Diagnosis
Starting in spring, emerging root weevil adults feed on the leaves of host plants, notching the leaf edges quite distinctively. The adult weevils rest during the day and feed on the leaf margins after sundown. Conifer needle damage is less evident than that on broad leafed plants. Needles may be severed and dropped from the tree. Adults feeding on new growth may result in sparse foliage.
Although top feeding of the adults is the most conspicuous damage, root feeding of the larvae does the most damage as they chew and girdle roots of their various host plants. Root weevil larvae can be devastating to conifer seedlings. Woody plant seedlings and propagation cuttings are at risk from both root and top feeding. Injured plants may develop a greenish-yellow cast that does not respond to fertilization and watering. Container grown plants may be severely stunted or killed. Injured plants may die suddenly.
Carrots and sweet potatoes affected by root feeders are not commercially viable and mostly not fit for the table. Damage to roots and crowns can weaken, stunt, and kill strawberry plants.
Life Cycle
Outdoors, there is one weevil generation per year. Greenhouse conditions may permit two generations annually. Many, if not most, root weevils dispense with the annoyance and inconvenience of males, producing the eggs of the next generation by means of parthenogenensis. Females deposit eggs in soil and debris near the host plant, starting usually in mid-summer, and continuing well into the fall, laying hundreds of eggs. Eggs hatch in about 10 days and the larvae move into the soil, feeding on root hairs and roots. Older larvae may girdle entire stems. Larvae are legless, c-shaped, and cream colored with brown heads. They spend the winter in the soil and continue their development in the spring as the soil warms. This second feeding period is the most destructive. Later in the spring, the mature larvae pupate in the soil and soon emerge as adult weevils. After several weeks of feeding on the leaves of host plants, adults begin the egg laying cycle again. Some adult weevils will not expire in the fall but will over-winter. These over-wintering adults will begin egg laying earlier than those adults just emerging from the pupae state.
Integrated Pest Management Strategies
(Control efforts may be directed towards both larvae and adults.)
1. Use nematodes can be applied as a soil drench to control root weevil larvae. Two commercially available cultures, Steinernema and Heterorhabditis are effective. Timing is critical. Apply nematodes when soil temperature is 55°F and soil is moist. Pull back any mulch, apply the nematodes and replace the mulch.
2. Apply pesticides. Chemical stomach poisons applied to the foliage are effective. Pesticides registered for use include acephate (Orthene), azadirachtin (Bio-Neem), imidacloprid (Merit), cyfluthrin and endosulfan (Thiodan). Pesticides should be applied to the foliage thoroughly, allowing excess to run off into the soil beneath the plant. Repeat at least twice at two week intervals. Pesticides appropriate for ornamentals may not be safe for vegetable and fruit crops. Read and follow the label instructions on all pesticides.
3. Use sticky substances. Adult weevils emerge from soil and debris at night and climb the plants to eat. Lower trunks of host plants may be wrapped with a four inch band of masking tape and the product Tanglewood applied to the taped surface. Check for buildup of dead insects regularly, and refresh as needed.
4. Try an organic solution. Weevils are attracted to water and may be trapped in shallow pans inset into the soil near affected host plants. Products that contain the organically derived insecticide spinosad are also labeled for leaf-feeding beetles on a wide variety of plants, and may be worth a try. Diatomaceous earth dusted at the base of affected plants is useful. In serious infestations, the lower sides of stems and leaf undersides should also be dusted.
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Dummer. ゛☀
2017年09月18日
Hens and Chicks plant (Sempervivum spp.) produce rosettes of thick leaves that cluster together in colonies of both large and small plants. Foliage color varies depending on the variety, but many feature green interior leaves surrounded by a ring of red or darker green foliage. Each Hens and Chicks rosette flowers approximately every four years, near the end of its life, but the plants are constantly producing new rosettes from the roots to replace those that fade. Hens and Chicks grow outdoors in U.S. Department of Agriculture hardiness zones 3 to 8, but you can grow them as houseplants everywhere.
1. Place potted plants in an area that receives full sunlight. Grow potted plants in a fast-draining succulent mix in a pot that contains at least one bottom drainage hole. Outdoors, plant Hens and Chicks in a sandy or rocky bed that drains quickly and receives full sun to part shade.
2. Water the plants only when the soil dries out completely. Water until moisture drips from the bottom of the pot and empty the pot’s drip tray after the soil finishes draining, usually within 30 to 60 minutes. Garden plants rarely require watering.
3. Cut old rosettes of foliage from the plant after they produce a flower and die back naturally. Cut the rosettes off the plant at ground level with a clean, sharp knife.
4. Remove offsets, or small new plants, from the outside of a group of Hens and Chicks to propagate new plants. Cut the small offsets from the small plants just below the soil surface with a sharp knife. Plant the rosettes in a well-draining bed or pot of succulent potting soil immediately after removal. The offsets quickly set roots and grow into new plants.
1. Place potted plants in an area that receives full sunlight. Grow potted plants in a fast-draining succulent mix in a pot that contains at least one bottom drainage hole. Outdoors, plant Hens and Chicks in a sandy or rocky bed that drains quickly and receives full sun to part shade.
2. Water the plants only when the soil dries out completely. Water until moisture drips from the bottom of the pot and empty the pot’s drip tray after the soil finishes draining, usually within 30 to 60 minutes. Garden plants rarely require watering.
3. Cut old rosettes of foliage from the plant after they produce a flower and die back naturally. Cut the rosettes off the plant at ground level with a clean, sharp knife.
4. Remove offsets, or small new plants, from the outside of a group of Hens and Chicks to propagate new plants. Cut the small offsets from the small plants just below the soil surface with a sharp knife. Plant the rosettes in a well-draining bed or pot of succulent potting soil immediately after removal. The offsets quickly set roots and grow into new plants.
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lrgarden：so beautiful
