By Brad Haire
University of Georgia
The first step is to scout your garden regularly, especially when conditions are wet and warm. During these times, vegetable plants are more susceptible to diseases caused by fungi and bacteria, said David Langston, a vegetable plant pathologist with University of Georgia Cooperative Extension.
Nematode damage is more evident, though, when the garden is dry. You can test your soil for nematodes by submitting a sample through your local UGA Extension office.
Viral diseases can show up anytime, Langston said.
Many plant diseases can be on or within the seeds. Because you can’t distinguish healthy seeds from diseased ones, buy seeds from a reputable dealer. Make sure you follow directions on when and how to plant them.
“Seeds should not be saved from year to year,” Langston said. “This is important to prevent a number of diseases.”
Using varieties that are resistant to plant diseases is the best way to avoid disease losses. The types of disease resistance for each variety are noted on the seed container or in a seed catalog.
Langston has a few more tips to help keep your garden disease-free.
1. Don’t plant your garden near or beneath trees. The shade will reduce the drying of plant foliage after rain and increase the chances of diseases. Besides, vegetables like a lot of sunlight, and the trees will compete for vital nutrients.
2. Rotate your crops. Grow the same or closely related vegetable plants in the same soil only once every three to five years, Langston said. This practice starves out most pathogens that cause stem and leaf diseases.
Vegetable families include: • Alliaceae (chives, garlic, leeks and onions) • Apiaceae (carrots) • Asteraceae (lettuce) • Brassicaceae (broccoli, Brussel sprouts, cabbage, cauliflower, collards, mustard, radishes, rutabagas and turnips) • Chenopodiaceae (spinach) • Cucurbitaceae (cantaloupes, cucumbers, honeydew melons, pumpkins, squash and watermelons) • Fabaceae (all beans, English peas and Southern peas) • Malvaceae (okra) • Poaceae (corn) • Solanaceae (eggplant, peppers, potatoes and tomatoes)
3. Plant a few rows of a crop like rye or corn around your main garden. This will tempt insects to feed there first, reducing the risk of diseases some small insects are known to carry.
4. When you water the garden, don’t splash soil onto plant foliage. If possible, run the water between the rows. Use a mulch layer of straw, bark, shredded paper or plastic to keep soil from splashing onto plants and keep fruit from touching bare ground.
5. If you use tobacco, wash your hands thoroughly before handling plants. This will prevent the spread of tobacco mosaic virus, which can infect many kinds of vegetables, particularly tomatoes and peppers.
6. After harvest, remove and destroy all plants from the garden and sanitize your garden equipment. This will reduce the overwintering of disease-causing organisms.