Take precautions to ensure healthy tomato plants

Posted8/18/2019 6:00 AM

Q. Are there any tips and tricks for growing tomatoes? I noticed some disease this year and am wondering if I did anything wrong.

A. We had a late spring, which seems to be the pattern of our season in this area. When it finally came, it brought lots of rain with it and colder than usual temperatures. Therefore, gardeners could not plant as early as they'd like. When they finally got their tomato plants in the ground, the less-than-ideal growing conditions often led to less healthy plants that are more susceptible to disease.


Some common diseases that tomatoes can get are called Septoria leaf spot and early blight. The first sign you will notice are yellow spots or yellow leaves near the bottom of the plant. The leaves then dry and drop off.

With early blight, small brown spots with concentric circles in them form on the leaf. With Septoria, the spots have a yellow halo. These leaves should be removed. Sprays with mancozeb or copper can be helpful, but should be used as a last resort if the disease is particularly bad.

Other diseases that are similar to Septoria and early blight are the fungal wilt diseases Verticillium and Fusarium. The leaves also turn yellow near the bottom of the plant and die. The leaves wilt along the whole plant even though the plant has enough water, or they might just dry up and die. These diseases come from the soil, so look for plants that are "VFN" resistant.

If your plants had either of these diseases, you should throw out any unharvested fruit and vines at the end of the growing season and clean up dried leaves.

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There are some tricks you can do to help your tomato plants to yield nice, delicious fruit. Even when these diseases aren't present, you should remove the leaves on the bottom 12 inches of your plant to allow for more air circulation. Plants should be staked and/or caged, depending on the type of tomato plant it is. The larger indeterminate (does not stop growing) plants may need to be staked and caged. Mulch them, too. This helps the water stay in the ground longer.

When watering, don't let too much water splash on the leaves, as this can encourage disease if the leaves don't dry before night. Water your plants each week.

Tomato plants should also be pruned. Pinch back the "suckers." These are a stem that grows between the main stem and the branch that will flower. Removing these improves air circulation, which helps prevent some disease and directs more energy to the formation of the fruit.

Plants can be fertilized when planted with an NPK fertilizer with equal parts such as 10-10-10. A consistently watered and well-fertilized plant could prevent blossom end rot. The fruit turns brown and mushy on the end. It can be caused from the plant not being able to take up calcium from the soil as a result of large swings in soil moisture, weather changes and not watering consistently.


These tips and tricks should make strong healthy plants with lots of delicious tomatoes.

-- Jennifer Richardson

• Provided by Master Gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines, and University of Illinois Extension, North Cook Branch Office, Arlington Heights. Call (847) 298-3502 on Wednesdays or email northcookmg@gmail.com. Visit web.extension.illinois.edu/mg.

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