Tomato

Tomato is queen of Kentucky vegetable gardens. This vine-ripened fruit is a delight for any table, from a formal dinner to backyard barbeque. Gardeners often have friendly competition for the “bragging rights” that go with the first ripe tomato of the season. But growing tomatoes is not without its challenges.

Early blight is perhaps the most common and damaging tomato disease in the home garden. It occurs to some extent every year wherever tomatoes are grown. Early blight tends to get off to an early start in the spring when wet weather occurs soon after transplants are set. These type conditions are ideal for infection of young tomato plants by the early blight fungus.

This fungal disease attacks leaves, stems and the fruit. The first and most noticeable symptoms are usually the small, irregular, brown spots that form on older, lower leaves. These spots may enlarge until they are one-half inch in diameter. Spots have concentric rings or ridges that form a target-like pattern and are often surrounded by a yellow halo. The disease moves upward, and by early to mid-summer, early blight has caused a “firing-up” of foliage over most of the tomato plants in the garden. The greatest damage tends to occur after fruit set. As the disease progresses, leaves turn yellow, wither, and drop from plants. Tomato plants severely infected by early blight produce low yields of undersized fruit. Generally, fruit are also show signs of sun-scald since leaves aren’t present to protect fruit from direct sunlight.

Where early blight affects the stem, small, dark, and slightly sunken lesions will occur. These lesions will elongate and form concentric markings similar to the leaves. Fruit with early blight will have dark, sunken, leathery lesions on the stem-end of the fruit. This damage may extend into the flesh of the fruit on older tomatoes and those heavily infected usually drop off the plant.

The fungus that causes early blight survives in old, diseased vines left in the garden and the garden soil. Cultural control practices can limit the exposure of tomatoes to this disease.

• Practice crop rotation by avoiding planting tomatoes and related vegetables (i.e., potatoes, eggplant) in the same garden space for three to four years.

• Purchase disease free transplants and/or seeds.

• Space plants for good air circulation.

• Plow under or remove old vines as soon as harvest is completed.

• Staking and mulching are important in an early blight control program, since staking keeps foliage and fruit from contacting the soil surface, and mulching cuts down on “soil splash” onto lower parts of the plant. Since soil particles often contain the early blight fungus, this is a good way of keeping the fungus from invading plants. Organic mulches (pine straw or even newspapers) are effective.

Fungicide, such as chlorothalonil (e.g. Daconil 2787) or maneb (e.g. Maneb), can be applied on a preventative basis. Be sure to read the label and follow label rates. Tomato cultivars, Mountain Fresh, Mountain Supreme, and Plum Dandy, have resistance to early blight.

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