Tomatoes are warm-season plants that thrive in the warmth of North Carolina's climate. Several tomato varieties do well in the state, including the Colonial, Flora Dade and Piedmont varieties, according to North Carolina State University. Even the best tomato variety can fall victim to one of the several insect pests, fungal diseases and management problems that are found in the southern U.S.
North Carolina State University lists the bacterial leaf spot disease (Xanthomonas campestris) as one of the most severe diseases to afflict the state's tomato plants. Symptoms include irregularly shaped spots on the leaves and blisters on the fruit. If left untreated, the entire plant can lose its leaves. Limit the tomato plant's chances of contracting the disease by not getting water on its leaves (avoid overhead irrigation). Treatment options include fungicides formulated with streptomycin, or fixed copper sprays. Apply chemical treatments once a week until the problem subsides.
Both the green peach aphid and the potato aphid are present in North Carolina. Though they're small, these tiny insects suck the juice out of the tomato plant and can cause severe plant stress. A standard insecticidal soap will kill the aphids. Releasing beneficial insects among the tomato plants, such as lady beetles, can also help control the aphids.
Tomato plants need lots of water, and periods of drought can lead to yellowing of the leaves, wilting and stunted fruit growth. This is especially true in a warm climate like North Carolina. Water the tomato plants once a week with enough to soak the soil to a depth of 8 inches, according to North Carolina State University. During periods of elevated heat, such as the summer months of July and August, North Carolinian gardeners are encouraged to mulch heavily around the plants.
The tomato fruitworm eats away at the tomato fruit from the inside out. Sprays formulated with the Bacillus thuringiensis bacteria will naturally kill the worms. Chemical pesticides made with methomyl or fenpropathrin will also eliminate the problem.