How to Identify Early Blight (fungus) on Tomato Plants
Tomato plants can have several problems over the summer. The plants in your garden may have more than one type of fungus and can also be infested with an insect such as a flea beetle, Hornworms, or aphids. All of these problems can be devastating to the plant and cause large amounts of defoliation, yellowing of the leaves, and sunscald on the fruit.
Positive identification of the problem is the first step in resolving the issue and moving forward with a treatment option. Even organic growers have options available on the market at local retailers such as Home Depot, Lowes, and Meijer. Taking the time to identify the problem is the first step to resolution. A very common problem for tomato plants is Early Blight. This is a fungus that attacks the entire plant including the fruit. The following will review identification and treatment options for home gardeners.
Symptoms of Early Blight (Alternaria solani)
Alternaria leaf spot (Early Blight) occurs during the hotter months of the summer. The tomato leaves will turn brown and black surrounded by yellowing of the leaves and stem (non symmetric spotting). The plant is covered with concentric circles all over the leaves and even the stem and fruits of the plant can be affected. Eventually the affected leaves will fall off the plant. If left untreated the disease can spread to the fruit of the plant and destroy your harvest. The best control for this type of fungus is through proper disposal of infected foliage.
Treatment Options for Early Blight (fungus)
Clip all affected plant material from the tomato plants and leave in a sealed plastic bag for 2 or 3 days in the sun. Then dispose of the yard waste through your local waste collection program. You can treat your plants with a fungicide, but be sure the product specifically states it will treat Alternaria. If the product does not state it will work against this type of fungus then your application of the fungicide will do very little to help control or clear up the problem. If you object to using fungicides you can take steps to prevent the problem next year.
Clearing debris away from your garden can help to eliminate the problem for subsequent years. Also, you may want to move the location of your tomato plants next year to prevent the spread of the fungus. The spores of the fungus can survive in the soil over the winter and germinate in the late spring. This year, after clearing the debris from your garden in late summer, cover the ground with a thick layer of organic material (3-4 inches deep) to help prevent the spread of the fungus the following year. You can also spray the ground with a fungicide prior to covering the ground with the organic material. Ensure the product eliminates Alternaria Leaf Spot. One product sold locally is Daconil Fungicide in a ready-to-use formula. Move your plants to a new location for 1 or 2 years before replanting in the same area. If the problem persist, leave the area free of tomato plants for at least 5 years.
Identification of the problem and then taking action can help your plants survive long enough to provide you with great tomatoes. If the problem is left untreated, the fruit will succumb to the fungus and will not be appetizing on the dinner table. Take action now to control the spread of Early Blight.
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