The Q&A Archives: Brown Tomato Top

Question: I grew several varieties of tomatoes started from seed. They are doing exceptionally well in my garden. I also gave some to a friend. All of his tomatoes (determinate & indeterminate) have skin that is turning brown from the top by the stem down. It is not patches, it is pretty much like a umbrella type pattern. The leaves of the plants look fine.
They are at different stages of brown. Some just starting by the stem, others brown well beyound half way down.
I can not find any information on this type of a problem. Any suggestions?

Answer: Tomatoes are very hardy plants, however, under certain circumstances various diseases can attack them. Your description sounds as if the tomatoes had some type of fungal or bacterial disease. Diseases are difficult to diagnose since many have similar symptoms. Yours could be Gray mold which is a common cause of fruit rot, and often appears as a stem rot. However, other fungal or bacterial diseases are also possibilities. To prevent this in the future, buy disease resistant plants. They are distinguished by the letters after the variety name, such as Celebrity VFFNTA where the initials stand for resistance to: A, Alternaria (early blight); C, Clodisporium (leaf mold); F, Fusarium wilt, race 1; FF, Fusarium wilt, races 1 and 2; N, Nematodes, S, Stemphylium (Gray leaf spot); T, Tobacco Mosaic Virus; V, Verticillium wilt.

Over fertilization could also be a contributing factor. Give your plants reasonably fertile soil, well-drained and high in organic matter, a consistent supply of clean, air-temperature water, and occasional minimal feeding without overfeeding. Go easy on the nitrogen which can worsen many diseases and disorders. Try not to wet the leaves, water the ground only, and do not work among the plants when wet. Mulched plots have fewer fungal outbreaks, because mulches prevent soil-borne fungi from splashing onto the lower leaves. Be sure not to plant in the same soil that was previously planted with tomatoes or any members of their family: potatoes, eggplants or peppers. A homemade spray made from 1 teaspoon of baking soda in a quart of water may help control fungal disease.

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