Fungicides can treat early tomato blight

By Lisa Stewart

Extension county

director, Webster County

What is wrong with my tomatoes?

According to Clarissa it is early blight; leaf spot Alternaria solani

Recommendation: Early blight of tomato is the most common and severe foliar disease of tomatoes in Mississippi. Symptoms can appear as spots with concentric rings (like a target board) on leaves, stems and fruit. Leaf spots usually appear first on the lower, older leaves.

In severe cases, plants may lose all of their leaves late in the season. Plants that have spots on the stem at the soil line often die. If they do survive their growth and yields are reduced. Fruit also can be infected and may drop from the vine prematurely.

The fungus survives between crops on infected plant material and in soil and on seed. Other plants in the tomato family, including potato, eggplant and weeds such as nightshade and horsenettle. Warm, wet or humid conditions favor the development of disease.

Good cultural and sanitation practices will help control early blight. Remove and destroy all diseased plants after harvest. Do not plant tomatoes on this site for three-five years.

Drip irrigation is recommended, rather than overhead watering. Practice weed control and remove volunteer tomato plants. Use of plastic mulches also can help reduce disease. Fertilize properly to keep plants growing vigorously.

Fungicides containing the active ingredient chlorothalonil (Bonide Fungonil), mancozeb or copper octanoate (Bonide Copper Fungicide) are labeled for homeowner use against early blight and many other common tomato diseases.

Begin fungicide treatment when first fruit clusters are formed, or earlier if symptoms appear or the weather favors disease development. Reapply fungicides every seven-10 days unless the label states differently. Always follow label directions.


This column is made up of questions presented to the Webster County Extension Service. Please get in touch in person or by phone (258.3971) or e-mail ( if you have questions you would like to see discussed here.