Gardening: Ruined tomatoes could mean virus or bugs

By Master Gardener | SCNG

Q My 87-year-old mother asked that I email you about a problem she’s having with her tomatoes. Every tomato seems to have these awful whitish-green mottled patches beneath the skin. We are stumped as to what might be causing this and how to treat it, and we could really use your help! We’d love to hear what you think is going on here. We appreciate your help!

A Icky, splotchy tomatoes can be caused by several things. Without knowing what the rest of the plant looks like, especially the leaves, I will offer a few guesses. My first guess would be some kind of virus, since tomatoes are susceptible to more than a few.

Tomato spotted wilt virus infection will cause dark brown spots on leaves and brown streaks on the stems of susceptible plants. It will also cause the growing tips to die back, which will stunt the plant’s growth. It’s spread by thrips, which are tiny insects that infest many plants.  This disease is more likely to appear when temperatures are high and especially when there’s a heavy thrip population.

Septoria leaf spot fungus is one of many ills that can affect tomato plants. GETTYIMAGES

You can treat for thrips, but the damage has already been done. My recommendation is to remove the affected plants and dispose of them in the regular trash (don’t toss them in the compost). Look for tomato varieties that are labeled “TSWV,” which indicates resistance to tomato spotted wilt virus.

Another possibility is cloudy spot, which is caused by stinkbugs. This appears on ripe tomatoes as off-white or yellow spots that have indistinct margins (blurry edges). The flesh underneath these spots is spongy and yucky. If you’ve seen stinkbugs in the garden, they may be causing this problem. Since stinkbugs are much bigger than thrips, this problem would be easier to diagnose. Take steps to get rid of the stinkbugs like removing weeds, debris and other hiding places. Hand-pick stinkbugs (I recommend wearing gloves) and remove any egg masses.

Every year, it seems that tomato labels are getting more and more crowded with those abbreviations indicating resistance to disease. Figuring out what diseases are prevalent and which planting varieties that are resistant to those diseases can do wonders for your success in growing tomatoes. You can do everything else right — mulching, fertilizing, regular watering, spraying with B.T. (caterpillar killer), weeding and pruning — and some virus shows up and ruins your crop.

Crop rotation is a good way to prevent some of these problems, but for many of us with small properties that’s not practical.

In the very near future, I will cover some of the most common tomato viruses, their symptoms, the bugs that help spread them, and virus-resistant cultivars.

Have questions?


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