Tomatoe fruit problem

Asked August 18, 2017, 2:03 PM EDT

I have a number of green tomatoes that have brown scaling over 90 % of the fruit. My research online seems to be similar to pictures of Sunscald, hornworm feeding, late blight, stink bug damage (cloudy spot). Do you have any thoughts and suggestions.

Broomfield County Colorado

1 Response

Thank you for your question! The photos show symptoms that are consistent with a virus, perhaps tomato spotted wilt virus or tobacco mosaic virus. Photos of the entire plant, and a closer view of the leaves, may help as viral diseases often cause foliar distortions, such as cupping or downturned leaves. Symptoms on the fruit usually begin with target-like spots that eventually coalesce into larger lesions. The tissue of the fruit becomes discolored and distorted as the infection progresses.

Late blight is a possibility as cool-to-moderate, wet weather favors the development of this disease, and we have seen those conditions in the last several weeks. The disease is caused by fungus-like pathogen called an oomycete.

Viral diseases in tomatoes are not treatable, and removal of the plant is recommended. Rotating tomatoes to a different area of the garden from year to year is a good cultural practice to ensure diseases do not build up in one area.

There are tomato varieties that are resistant to viral diseases. Seed packets will indicate resistant qualities. Heirlooms tend not to be resistant.

For more information about tomato diseases, please see CSU Extension Fact Sheet "Recognizing Tomato Problems", which includes a list of common disease symptoms seen on fruit and foliage. Late blight plants should also be culled as the disease can spread through spores, especially at this advanced stage.

Clean up all diseased plant material as soon as possible and dispose of it in the trash. It is a good idea to remove and dispose of all tomato, pepper, and potato plants at the end of the season if you've had diseased plants as the same diseases can affect all of these related crops.