Campbell Vaughn: Tomato diseases can be more plentiful than plants

NATIONAL GARDENING ASSOCIATION Tomato spotted wilt virus is spread by thrips. Symptoms include leaves curling up, wilting and having bronze spots. Younger plants may die. If the plant lives long enough, the tomato fruits have yellow circles all over them.

It’s that time of year — fresh tomatoes from the garden and tomato sandwiches. Growing that tomato might not be as easy as eating it. The Compendium of Tomato Diseases has over 250 pages of tomato diseases. I think I may have gotten calls about 90 percent of those diseases. Woe unto me!

 

The disease I get the most calls about is Tomato Spotted Wilt Virus (TSWV). It is a virus that is spread by thrips. Typically, the thrip feeds on weeds with the virus and passes it on to your tomato. The symptoms include the leaves curling up, wilting, and having bronze spots. Younger plants may die. If the plant lives long enough, the tomato fruits have yellow circles all over them.

Resistant varieties exist and I recommend planting a few of these. Some of them are not the tastiest but at least you will get a few tomatoes. Amelia, BHN-602, Crista, and Sophya are some of the varieties.

Other complaints heard are the leaves get spots, turn yellow, and drop off. This is a slower death of the plant. The culprit can be early blight, late blight, septoria leaf spot. All of them weaken the plant and spread to other leaves eventually causing the defoliation. You can’t get good tomatoes without leaves.

If the above diseases are not bad enough, tomatoes are very susceptible to nematodes, which feed on the roots. Have you ever dug up a tomato to find the roots covered with small galls? Root knot nematodes are the problem. Other nematodes exist that are inside the roots and can’t be seen. They all serve to weaken the plant.

Only a few varieties of tomatoes are available to us as transplants. As you may have noticed, there is basically one supplier to the big box stores. You may have to resort to growing your own. The more letters a tomato has after its names means it is resistant to more diseases.

Heirloom varieties have really become popular in the last few years. They boast greater flavor but lack shelf life, resistance to diseases and nematodes, and are not as hardy. To overcome these problems, some growers have resorted to grafting the heirloom varieties to a hardier rootstock. The plants are premium priced but they don’t “bite the dust” as soon.

With TSWV and most tomato diseases, there is no magic formula (pesticides) to cure the plant. Rogue the plant by pulling it up and dispose of it in the garbage, not your compost pile. As I have told many people through my stint as a county agent, just plant more tomatoes than you need. That way you will be assured of some tomato sandwiches and maybe even a few canned jars.

Other tomato-growing tips are:

Use drip irrigation rather than overhead. Keeping those leaves dry goes a long way in managing diseases as most diseases need moisture (or humidity) to thrive.

Mulch your plants. This keeps the soil at a more even temperature, keeps pathogens from splashing on the leaves, keeps weeds at bay, and holds soil moisture.

Keep your soil fertility high by fertilizing, adding organic matter, and keep the pH between 6.0 to 6.5. Even watering and adding calcium by liming will help keep the blossom end rot from attacking your tomatoes.

What says summer more than a plate of fresh tomatoes?

Reach Campbell Vaughn, the UGA Agriculture and Natural Resource agent for Richmond County, by e-mailingaugusta@uga.edu.

 

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