DM – Downy Mildew
Scientific Name: Peronospora farinosa, Peronospora parasitica, Pseudoperonospora cubensis
Type: Fungus
Downy mildew is a fungal disease that affects the growth of beets, broccoli, cantaloupes & melons, cauliflower, cucumbers, spinach, Swiss chard, and watermelons. Downy Mildew is most serious for cucumbers, which can drop dead in a week and stop producing any fruit to harvest. The disease affects both seedlings and mature plants.The infected leaves are retarded in growth, turn yellow then brown, and turn downward. A white to gray color mold appears on the underside of the leaves. The leaves will wilt and eventually die. The disease can spread rapidly under favorable conditions and infect the entire field. The infected plants should be removed and burned to avoid further infestation. The disease is favorable when temperatures are 58-72 F and usually occur in early spring and autumn in cooler weather when moisture and humidity are very high. Fungicides can help manage the disease. Good air circulation and increasing space between the plants can help control and prevent the disease, so use wide plant spacing to promote drying of the leaves. The best option is to use disease resistant varieties.
FW – Fusarium Wilt
Scientific Name: Fusarium oxysporum
Type: Fungus
Fusarium Wilt is a fungal disease that affects the growth of cantaloupes & melons, cauliflower, eggplants, peas, peppers, squash, tomatoes, and watermelons. It is one of the most devastating of all soil-borne diseases. It attacks the roots of the plants and moves up the stems. Symptoms include stunting and wilting. Plants don’t always die, but it slows growth and reduces yields. Infected seedlings will damping off, wilt, and die. If you stick with fusarium wilt resistant tomato varieties you don’t have to worry. Many of the older heirlooms don’t have any resistance to the disease, so if you grow these then you should keep an eye out for it. 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, as the disease can survive in the soil for 7 years. The best option is to use disease resistant varieties.
PLRV – Pea Leaf Roll Virus
Type: Virus - Luteovirus
Pea Leaf Roll Virus, also known as Bean Leaf Roll Virus, is a disease that affects the growth of peas. It is primarily found in Northwestern parts of the United States (Idaho, Oregon, and Washington) and Europe (France, Germany, and Netherlands). In 1980, a severe epidemic of the disease caused severe crop losses in southern Idaho, where 80% of the peas are produced in the United States. Symptoms include yellowing and mottling of leaves, sometimes downward leaf rolling, severe stunting of the plants, and the death of plants. The virus can cause substantial crop loss and complete crop loss. The virus is transmitted by aphids and is not transmitted by seeds. The virus survives for long periods in infected alfalfa. Mild winter temperatures favor survival of the virus, thus the disease can be greater the following spring. The infected plants should be removed and burned to avoid further infestation. Plan on using a 3 year crop rotation and avoid planting in the same location, year after year. Insecticides for aphids can control the disease. The best option is to use disease resistant varieties.