Gardening Harmful insects Vegetables

White or Yellow Spots on Tomatoes

Tomato speckled with yellow spots.

By Larry Hodgson

Question: What’s causing the yellow or white spots on our tomatoes? Underneath, the flesh is white, spongy and inedible and we have to remove almost half of the tomato to eliminate it. Is there a cure?

Luce Hamel

Answer: Your tomatoes are suffering from cloud spot. This sounds like a disease, but is actually the result of injuries due to piercing insects, usually stink bugs or leaf-footed bugs. There are several species that visit our gardens and cause this kind of damage.

Adult brown marmorated stink bug, beige mottled with brown.
The brown marmorated stink bug (Halyomorpha halys) is probably the bug that causes the most damage to tomatoes. This is an adult bug. Photo: William Morris, Public Domain pictures

Stink bugs are a foul-smelling, shield-shaped insects that can be, depending on the species and its degree of maturity, brown, green, red or other colors. Leaf-footed bugs, mostly seen in fairly mild climates, are similar, but more elongated with leaflike structures on their legs. 

The adult (and in many species, also the nymph) pierces the fruit with its rostrum and injects it with enzymes which liquefy the tomato flesh so it can then suck it out, leaving a wound that turns white or yellow on the outside over time.

Tomato cut to show hard, white sections under the skin.
In cloud spot, white masses of hardened flesh form under the fruit’s skin. Photo: ask2.extension.org

Inside the fruit, just under the skin, harder white masses form. They’re not very appetizing and need to be cut out with a knife when preparing the tomato. That wastes a lot of tomato flesh … and time.

You can often control this insect by rinsing the fruits with water daily shortly after they start to form or by hand-picking the bugs and dropping them in a bucket of soapy water where they’ll drown. To make picking them easier, place a cloth under the plant and give it a shake. That usually causes the bugs to drop off and then you can just pick up the cloth and shake it over soapy water. 

Some people find they get good results by harvesting the bugs with a hand vacuum cleaner.

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

6 comments on “White or Yellow Spots on Tomatoes

  1. I haven’t had the issue with tomatoes, but the stink bugs are here even sitting on window screens on the second floor. Last year, they hung around all through the winter which was definitely a first. I wish it was the last but apparently not.

  2. Iceni Summersides

    I also have white spots on my tomatoes but they were caused by hail. Some of the tomatoes were too damaged, just a few are salvageable.

  3. This is good to know. I just replanted some tomato sprouts the other day.

  4. Pingback: When Brown Marmorated Stink Bugs Invade Homes – Laidback Gardener

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