PEMV – Pea Enation Mosaic Virus
Type: Virus - Enamovirus
Pea Enation Mosaic Virus is a disease that affects the growth of peas. Symptoms include bright yellow mosaic on the leaves. downward leaf rolling, blistering, severe stunting of the plants. Pods are distorted, split open, shows enations and contain few, if any, seeds. 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 weeds. 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. Predators, like lady bugs, can be used to prevent an outbreak of the virus. The best option is to use disease resistant varieties.
PM – Powdery Mildew
Scientific Name: Erysiphe betae
Type: Fungus
Powdery mildew is a fungal disease that affects the growth of beets, cantaloupes & melons, cucumbers, peas, squash, Swiss chard, and tomatoes. The fungal disease may cause poor growth of the fruits in cucumbers if the infection is severe. The leaves of the cucumber begin to wither and then fall off prematurely. The disease usually affects older leaves. The leaves tend to turn a light green or a yellow green when infected. A powdery white or light gray color mold appears on the underside of the leaves. An odor similar to that of a musty basement is noticeable in fields with severe powdery mildew. The disease can spread rapidly under favorable conditions and infect the entire leaves within a week. The disease is favorable with long periods of dry weather, warm days, and cool nights, and fluctuations of day/night temperatures. The most favorable temperatures are 54-81 F and usually occur in early spring and autumn when moisture and humidity are very high. The disease can spread rapidly and can infect a field within 5 days. Fungicides for powdery mildew can help manage the disease. Good air circulation and increasing space between the plants can help control and prevent the disease. The best option is to use disease resistant varieties.