A – Anthracnose
Scientific Name: Colletotrichum lagenarium
Type: Fungus
Anthracnose is a world-wide fungal disease that affects the growth of cucumbers, tomatoes, and watermelons. This disease is most common in the southern, mid-Atlantic, and mid-Western parts of the United States. Symptoms include lesions on the leaves and then yellowish circular spots begin appearing on the leaves. On watermelons the spots are irregular and turn dark brown or black. The most striking symptom is circular, black, sunken cankers appear on the fruit. When moisture is present, the black center of the lesion is covered with a gelatinous mass of salmon colored spores. With tomatoes, the disease mainly affects the tomato, but also can infect leaves, stems and roots. Sunken water soaked circular spots appear on the tomatoes. Leaves show symptoms of small circular spots with yellow halos. It can cause significant yield loss and even total crops losses. The diseased tomatoes are usually unmarketable. The infected plants should be removed to avoid further infestation. Increase space between the plants to maximize air flow and drying of the leaves. The disease is favorable when temperatures are 75-82 F and usually occur when moisture and humidity are very high. Plan on using a 3 year crop rotation and avoid planting in the same location, year after year, as the disease can survive in over winter on crop debris. Proper tillage practices may be helpful in managing the disease. Fungicides can help manage the disease. The best option is to use disease resistant varieties.
Ccu – Scab
Scientific Name: Cladosporium cucumerinum
Type: Fungus
Scab is a world-wide fungal disease that affects the growth of cantaloupes & melons, cucumbers, gourds, pumpkins, squash, and watermelons. Symptoms include pale green spots appear on the leaves which turn to gray spots and may have a yellow halo surrounding the lesion. The leaves become wrinkled and have ragged holes. The dead leaves crack and eventually fall off the plant. Cucumbers, pumpkins, and squash have sunken spots covered with greenish black velvety fungus. The fungus spores are spread by wind, insects, tools, and workers. The scab fungus overwinters on the seed, in crop debris, and in soil. The infected plants and vegetables should be removed, burned, or tilled in to avoid further infestation. The disease is favorable when temperatures are 59 - 77 F and usually occur when moisture and humidity are very high. Plan on using a 2 year crop rotation and avoid planting in the same location, year after year, as the disease can survive in over winter on crop debris. Proper tillage practices may be helpful in managing the disease. Control weeds, by tilling. Fungicides can help manage the disease. Use drip irrigation instead of overhead sprinklers if possible. Keep the day temperature in the 80's and have proper air circulation in greenhouses. The best option is to use disease resistant varieties.
CMV – Cucumber Mosaic Virus
Type: Virus - Potyvirus
Cucumber Mosaic Virus is a world-wide virus disease that affects the growth of cantaloupes & melons, cucumbers, eggplants, gourds, peppers, pumpkins, spinach, squash, tomatoes, and watermelons. Symptoms include stunted or dwarfed plants, mottling, yellowing, distortion, and wrinkling of the leaves with the edges curling downward, and reduced growth rate and yields. The symptoms on leaves known as "shoestring" effect causes young leaves to appear narrow. The leaves will die and fall off, leaving part or most of the plant bare. The virus causes cucumbers to turn pale and gray, become bumpy and oddly shaped, and have a bitter taste. The virus causes peppers to have severe leaf damage with mosaic and necrotic rings. The peppers may have rings and spots. Tomato plants are usually stunted and have poorly shaped leaves and can cause partial or total crop loss. Plants infected with the virus have little or no marketable fruit. The virus can reduce yields and fruit quality. It is spread by aphids, seeds, and weeds. The virus overwinters in many perennial weeds. The infected plants should be removed to avoid further infestation. This virus cannot live in extremely dry conditions. The disease is favorable when temperatures are 79-89 F when aphid infestation is great. Symptoms usually begin to show in June. Plan on using a 3 year crop rotation and avoid planting in the same location, year after year. Keep the fields weed free as infected perennials can harbor the virus. Proper tillage practices may be helpful in managing the disease. Insecticides for aphids are of limited value to control the disease. Spraying the tomato plants with mineral oil can delay the aphids from spreading the virus.The best option is to use disease resistant varieties.
PRSV – Papaya Ringspot Virus
Type: Virus - Potyvirus
Papaya Ringspot Virus is a virus disease that affects the growth of cantaloupes & melons, cucumbers, pumpkins, and squash. Papaya ringspot virus is primarily a problem in the southern and western regions of the United States. Symptoms include yellowing and vein-clearing of young leaves, yellow mottling of the leaves, distinctive ringspot patterns on the fruit, and fruit quality, particularly flavor, is adversely affected. The infected plants should be removed to avoid further infestation. It is only spread by aphids. There is no cure for papaya ringspot disease. Insecticides for aphids are of limited value to control the disease. The best option is to use disease resistant varieties.
WMV – Watermelon Mosaic Virus
Type: Virus - Potyvirus
Watermelon Mosaic Virus is a virus disease that affects the growth of cantaloupes & melons, cucumbers, gourds, pumpkins, squash, and watermelons. Watermelon mosaic virus is primarily a problem in the southern and western regions of the United States. Symptoms include stunted or dwarfed plants, yellow or light green mottling, blistering, marginal yellowing, leaf distortion, and reduced growth rate and yields. Losses of 50 percent or more in yield and fruit quality may occur. The fruit frequently show color breaking and warts. It is only spread by aphids. Symptoms usually begin to show in June. Plan on using a 3 year crop rotation and avoid planting in the same location, year after year. Plastic mulches have been shown to reduce losses. Insecticides for aphids are of limited value to control the disease. The best option is to use disease resistant varieties.
ZYMV – Zucchini Yellow Mosaic Virus
Type: Virus - Potyvirus
Zucchini Yellow Mosaic Virus is a world-wide virus disease that affects the growth of cantaloupes & melons, cucumbers, gourds, pumpkins, squash, and watermelons. Symptoms include stunted or dwarfed plants, mottling, yellowing, distortion, blistering, and wrinkling of the leaves, and reduced growth rate and yields. The virus can cause total crop lose. The symptoms on leaves known as "shoestring" effect causes young leaves to appear narrow, and fern-like appearance of the leaves. The virus causes cucumbers to become bumpy and oddly shaped, and have a bitter taste. Cantaloupes & melons and watermelons are malformed and often develop deep cracks. Squash and pumpkins can develop knobby areas. Plants infected with the virus have little or no marketable fruit. The virus can reduce yields and fruit quality. It is spread by aphids and seeds. The infected plants should be removed to avoid further infestation. Plan on using a 3 year crop rotation and avoid planting in the same location, year after year. Keep the fields weed free. Proper tillage practices may be helpful in managing the disease. Insecticides for aphids are of limited value to control the disease. Using transparent or silver plastic mulches have been shown to repel aphids and delay the virus from spreading. Ladybird beetles can be effective at naturally controlling aphid populations. The best option is to use disease resistant varieties.
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