Tomato Plant Problems

Asked July 10, 2015, 3:51 PM EDT

I am from the Antrim County Extension Office and client was in with questions on his tomato plants. For the last several years his plants are wilted and spotted. He said the problem starts at the base of the plant and works it's way up. I have attached a few pictures for you reference. Any information you can give to help him would be appreciated.

Antrim County Michigan

1 Response

This is a tomato fungal disease called Septoria Leaf Spot. The disease begins on the lower leaves with small brown spots and some enlarge to have gray or tan centers. The spots get a yellow halo, the leaf turns yellow, then brown, The brown leaf gets crispy and falls off. The broken down leaf with the fungus in the soil is one of the ways tomato plants get Septoria next year.

The only way to prevent Septoria is to begin spraying before the plant shows any symptoms. If the client begins spraying now, it is difficult to know how much of the plant can be protected. More leaves than the ones with current spots have the fungus developing inside. So he will spray for several weeks and may not see the disease stopping. But if he does not spray, the plants die and there is a greatly diminished crop or no crop.

Chlorothalonil is the fungicide needed and it can be found in Daconil or Fungonil. Follow label directions but it is usually spraying on a 7-10 day repeat until harvest is done. If it rains or the plants are overhead irrigated, the plants need to be resprayed immediately. Chlorothalonil is water soluble.

Use a pressurized sprayer that has never been used with weed killers. Do not use a hose-end applicator. Spray the bottoms of leaves as well as the top to the point of run-off. Do not leave unused spray in the sprayer. Mix fresh each time.

Next year, begin spraying chlorothalonil on tomatoes to protect them before any symptoms appear. That is at the end of June. Septoria will be back next year... guaranteed. It does not matter if you move the garden to another location or put plants in pots. Septoria can live on a number of plants outside of the garden.