Fungicide for Tomato Diseases

Options

• When battling fungal diseases, two types of fungicides are available. The first class includes chlorothalonil, mefenoxam, maneb and mancozeb. These fungicides carry the highest success rate against tomato fungal diseases. The second group includes copper fungicides. These products actually are helpful in battling bacterial tomato diseases but also can be useful against fungal infections. You should use a chemical from the first group for at least seven days, followed by the second group’s copper fungicides for seven days, experts at the University of Minnesota Extension Services recommend. Continue this cycle to get the best tomato disease-fighting results.

Targets

• A fungicide for tomato diseases can attack a wide range of fungi. For example, common target fungi include late blight and early blight. Late blight is a result of the fungus Phytophthora infestans and is characterized by dark blotches moving from the edge of a leaf to the leaf’s inner part. Greenish spots also appear on tomatoes and take over most of the fruit. Meanwhile, early blight caused by the fungus Alternaria solani is present on the bottom leaves of a tomato plant and appears as big black blotches on the leaves. This fungus can cause the tomato plant to lose its leaves. The tomatoes also end up falling off the plant before they are fully grown.

What to Avoid

• When choosing a fungicide for tomato diseases, note that some products such as 2,4-D easily harm tomato plants, so stay away from them. The chemical 2,4-D -- also known as dichlorophenoxyacetic acid -- can cause tomato plant leaves to be coriaceous, or leathery and stiff, and chunky. In addition, the leaves can curl up, and the fruits will only become partly ripe. The affected tomato plant also can grow to a below-normal height as a result of the use of 2,4-D.

Other Information

• When using a fungicide for tomato diseases, simply follow the directions on the label to know how much of the chemical to apply, how to apply it and when to use it. Spray the chemical as near the ground as possible to prevent the fungicide from drifting to other plants. Also, avoid using the fungicide for tomato diseases on a windy day. Make sure the spray nozzle’s pressure is low as well to contain its spread.