The Q&A Archives: Tomato Trouble-Shooting

Question: Since moving to the Harrisburg, PA area 10 years ago, I have not been able to grow the wonderful tomatoes I used to grow. No matter what variety I use, the plants always start showing dark spots on the leaves (usually mid-plant) which progresses to yellowing and browning and death of the affected sucker. The tomatoes themselves almost all become either mottled with a yellowish-brown coloration and/or form large dark blemishes the size of a dime to a quarter which become sunken and start to rot. Cracks also form on almost all of the tomatoes and usually become infested with tiny hard-shelled insects. The summers here have varied greatly, but usually summer starts early and hot with almost no spring, late summer is usually very hot and humid. Due to the tree-line they only get full sun 3/4 of the day. Help! Manfred

Answer: Kodila Etters, PA A.It sound as though you have a variety of problems. First of all, the spots on the leaves may be caused by a fungus, probably alternaria. To combat fungal diseases, practice good sanitation: promptly remove and destroy any diseased plant material, keep weeds down, and rotate crops. Keep plants well-spaced to promote good air circulation. Next, be sure to choose disease-resistant varieties. Look for the letters V, F, and A after the variety name. Keep a close eye on water availability. Those sunken black spots may be blossom end rot--this happens when a rainy spell is followed by a dry time. The stressed roots cannot take up enough water, so try to keep water consistantly available. A calcium deficiency can exacerbate the problem; consider adding calcium in the form of lime if you have not done so and a soil test indicates a calcium deficiency. A consistent supply of water may also help reduce the cracking problem you are having. Try mulching with a 4" to 6" layer of hay or straw to keep soil moisture constant. (The black insects you see are probably feeding on the flesh exposed by the cracks.).

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