The Q&A Archives: Yellow tomato blotches

Question: This past year some of my tomatoes had yellow blotches on the skin with a dark pinprick in the middle of each one. Under each blotch was a white, spongy area of flesh that went maybe 1/4 inch deep. What caused this damage? Mary Farrell Oroville, CA

Answer: The culprit is the stinkbug, says Tim Hartz, vegetable specialist at the University of California, Davis. During the last three years, we've seen a lot of stinkbug damage on tomatoes and peppers in this area, he says. After overwintering in woody areas, especially on blackberries near streams, adults fly into gardens in spring when temperatures reach 70 F. They lay cream-colored, barrel-shaped eggs in masses on the undersides of leaves. The nymphs feed on leaves, reaching adulthood in six weeks. Theadults feed on young fruits, piercing the skins to draw fluids and causing the yellow blotches and spongy texture. There are multiple generations in a year. Although the damage is very noticeable, it's only cosmetic and often limited to a few fruitson each plant or to plants on the edges of your garden, says Hartz. The fruits are perfectly good to eat after you cut away the damage. Home-garden sprays usually aren't effective, Hartz cautions, because they need to make contact with the stinkbugs to kill them and these insects are very mobile and therefore hard to find. He suggests reducing the stinkbug population by searching for and destroying egg masses on the undersides of the leaves in May and June, cleaning up the garden thoroughly in fall and removing any bushy growth, such as wild brambles, around the garden where adult stinkbugs overwinter.

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