Issue: July 9, 2005

Replant tomatoes in June?

I have had curly top virus in my tomatoes before, but this is the first time they have infected all my tomato plants. Every plant turned a strange shade of green and became stunted, so I pulled them up. Can I replant tomatoes? Do I have to move to a different location in the garden?

When we saw a great abundance of mustard weeds across New Mexico following the moist winter, we knew curly top virus would be a problem for gardeners, so your question is not a surprise. Many gardeners have lost the majority of their tomatoes and chile plants because of curly top. Dr. Mike English, Superintendent of the NMSU Los Lunas Agricultural Science Center, said that on the research farm the plants were infected by both curly top virus and tomato spotted wilt virus (similar symptoms in the plants).

If you want to try growing tomatoes this summer, you can try replanting (transplants, not from seed). Time is getting short, but you may succeed with the smaller fruited tomato varieties. Dr. George Dickerson, NMSU Extension Horticulturist, warns that gardeners planting this late (except in southern New Mexico) will not see much production. To maximize production, you may need to cover the plants when frost is predicted in the autumn to give the plants a little more time to mature their fruits. You may also find that you will need recipes for green tomatoes. (Your local NMSU Cooperative Extension Service office can provide these.) According to Dr. Dickerson, you may also plant other crops that mature quickly (bush beans) or will tolerate a little frost in the fall (cool season crops - broccoli, cabbage, cauliflower, lettuce).

The virus diseases mentioned do not persist in the soil like some fungal and bacterial diseases. For this reason, it is safe to replant in the same soil. If there are other diseases involved, relocating to other areas of the garden is wise. If you think there were some fungal diseases, now is also a good time to "solarize" the soil to treat for this problem.

Solarization is treating the soil by solar heating to kill disease organisms and weed seeds in the upper levels of the soil. This is accomplished by moistening the soil, covering it with clear plastic, sealing the edges of the plastic with soil over the edges, and allowing sunlight and the greenhouse effect under the plastic to heat the soil to temperatures above 130 degrees. These temperatures kill many disease organisms and weeds, reducing problems next year. It may take several weeks to generate sufficient heat to a sufficient depth into the soil. If you wish, you can remove the plastic after a few weeks, rototill (or otherwise turn the soil) to bring up deeper disease organisms and weed seeds, and then repeat the solarization process to kill these pests as well.

Once the soil has been solarized, you can plant fall crops (not tomatoes, corn, chiles, etc.) or you can wait until spring to plant traditional summer crops. This treatment will not prevent curly top virus or tomato spotted wilt virus, but the loss of the crop does give you the opportunity to treat for other problems in mid-summer when you can maximize the soil heating. You have the option to replant or to treat the soil to reduce future problems.

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Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!