« Back to all News

Why Are My Tomato Leaves Turning Yellow?

Yellow_Tomato_LeavesHello, I live in a condo and have gardened my front yard for 10 years. I have 9 tomato plants. Each spring I dig a new hole, discard the earth, and fill with enriched soil. 1 of 9 has gone bad. Yellowing of leaves up the entire plant, lots of bumps on the stem, and fuzz or powder on plant. Any ideas?  Thank you, Jim

Answer: Well there are a number of possible reasons for the such symptoms. First I would suggest that you not discard the previous soil but simply augment it yearly with compost. By using highly enriched soil, you are causing the roots of the tomato plant to not want to expand past the good stuff, thus actually weakening it, especially with the heat and drought conditions of this summer. It’s always good to add compost to the soil in the spring, but don’t over-enrich it.  Too much of a good thing isn’t better. This overly rich soil could also be holding too much moisture, which is not good for the plant and could be introducing other diseases.

Another common problem with tomatoes is the susceptibility to several fungus issues, especially verticillium wilt or fusarium wilt. There are new plant varieties that have been developed to be less susceptible to these problems.  Check your variety’s specs, as these characteristics are included on the label. Do some research online for specific signs and treatments; they differ slightly, so you need to know which one you have. Both will suggest crop rotation, because they are soil-borne pathogens. If you are in a small lot and cannot move them, then you might consider using pots, or a raised bed. Also check the pH of your soil: tomatoes want a nice neutral soil, 6.5 -7.0, and in PA you might be too acidic.

The bumps are normal on the lower portion of the stems. They are called stem primordia and are just areas that could develop into roots, if needed. When they develop higher on the stem, it could be caused by excess moisture in the soil or too-high humidity levels. While they are not a problem, if your plants are developing these in the top portions, then it’s a signal that they are staying too wet. You might want to use a soil moisture meter and check before watering.

The last couple of years have also presented significant issues with unusual temperatures and water, or lack thereof, which are outside the norm for most home vegetable gardeners.

Best of luck. Karen

Leave a Reply

Discount Coupons
Ask a Master Gardener