Early Blight And Septoria Leaf Spot Rampant On Pennsylvania Tomatoes

According to a news release from Penn State University, early blight and Septoria leaf spot are present in Pennsylvania tomato fields due in part to the frequent rain events and persistent high relative humidity.

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Early blight, caused by caused by the fungus Alternaria solani, develops under warm temperatures (75°F to 85°F) and high relative humidity, heavy dews or significant rainfall. Septoria leaf spot, caused by the fungus Septoria lycopersici, prefers slightly cooler temperatures between 68°F and 77°F.

Both diseases are easily spread when the spores are splash-dispersed during rain events, and typically start on the lower leaves and work up the plant causing defoliation. Early blight lesions are initially small, brown to black in color and may be surrounded by a yellow halo.

During the season, maximizing air flow by suckering and staking and tying the plants and minimizing working the field when it is wet will help minimize spread. Protectant fungicides like chlorothalonil, mancozeb, and Gavel will also help reduce spread, but good coverage is important.

To read the full list of symptoms and control measures from Penn State, click here.

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Source: Penn State University news release

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