Published on 04/21/11

Plant TSWV-resistant tomatoes, provide calcium for success

By William G. Tyson

Growing tomatoes is a popular hobby for many home gardeners. It has been difficult to grow tomatoes during the past several years in Georgia because of factors like extreme temperatures, dry conditions, tomato spotted wilt virus and blossom-end rot diseases.

Tiny thrips carry the virus

TSWV is a virus detrimental to tomato plants. Tiny insects called thrips cause it. The insects have cost Georgia farmers millions of dollars through the damage they cause to tomatoes, tobacco and peanuts.

The thrips that carry the virus and transmit it to the tomatoes cause the plant’s foliage to turn purple. The leaves also have a bronze cast. The fruit has mosaic or mottled light-green configurations on the outer fruit peeling.

There are several varieties of tomatoes available that are resistant to the virus. They include Amelia, Crista, BHN 444 and BHN 640. Check with your local agriculture and garden supplier for the availability of these varieties.

Monitor pH to prevent blossom-end rot

Blossom-end rot appears as a small water-soaked spot near the blossom end of the tomato. The spot eventually enlarges and becomes dry, sunken and brown or black. Insufficient calcium uptake by the plant causes blossom-end rot.

Any condition that reduces the plant’s roots ability to absorb water sets the plant up for blossom-end rot. This can be caused by root-rotting fungus, nematodes, too much water, not enough water, soil compaction or too much fertilization.

To prevent blossom-end rot, maintain a soil pH between 6.0 and 6.5 and supply adequate levels of calcium through applications of dolomitic limestone or gypsum. Avoid drought stress and extreme moisture fluctuations by using mulch and irrigating deeply once or twice a week.

Avoid over-fertilizing plants with high ammonia-calcium-nitrogen fertilizer. Excessive nitrogen can depress the uptake of calcium. Foliar applications of calcium with products like Blossom End Rot Stop are only short-term fixes.

Following these tips will help you grow better, healthier tomatoes this growing season.

William Tyson is the University of Georgia Cooperative Extension coordinator for Effingham County.
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