Blackwelder column: Weather brings out worst in tomatoes

Published 12:00 am Friday, July 6, 2012

SALISBURY — Unusually hot weather over the past few days is causing a multitude of problems for this season’s tomato crop. However, there are some other situations that are causing problems with tomatoes. Cooperative Extension always receives quite a few questions from homeowners when their tomato crop is not performing as well they would expect. Below are a few questions received about tomatoes.
Q: My tomatoes are rotting on the end even though I had applied lime as a preventative measure. I thought that if I applied lime it would prevent blossom end rot. What am I doing wrong?
A: Blossom-end rot is actually a calcium deficiency sparked by periods of drought or in some instances, too much water. Tilling or hoeing around the roots also contributes to the problem. Adding lime before planting can be of benefit, but is no substitute for consistent irrigation. Tomato plants need to be evenly moist. Add mulch to your tomatoes to help keep moisture levels constant. Also, many tomato varieties are predisposed to blossom end rot; it’s always a good idea to plant different varieties for this reason.
Q: My tomato plants look great. They have beautiful foliage and no diseases. They are loaded with fruit, but when they ripen, they are all small. What can I do to make them larger?
A: Most likely you’re doing everything right; you have purchased mislabeled tomato variety. Seed or tags often get mixed during planting.
Q: (Sample brought in for diagnosis). My tomatoes and other vegetables are withered and don’t look right. It looks like a disease that is spreading through all my vegetables. What is the problem and how do I correct it?
A: Your tomatoes and other plants have herbicide damage. Roundup and other herbicides will drift during windy or hot weather, causing the foliage to wither and appear contorted. The giveaway is other plants have the same signs. Plant diseases are usually, but not always, host specific.
Q: My tomato plants look very good, but they are all vines with little or no fruit. What could be my problem?
A: Temperature extremes over the past few days are a major factor in tomato bloom drop. However, over fertilization, especially with nitrogen at planting, also yields heavy vine growth and low fruit set. Insufficient light is another reason for poor fruit set.
Darrell Blackwelder is the County Extension Director with horticulture responsibilities with the North Carolina Cooperative Extension Service in Rowan County. Call 704-216-8970