Avoid early blight with clean soil

Q. What’s wrong with my tomatoes?

Mary from Boardman

A. Tomatoes have their share of disease problems no matter what happens. Most of us deal with the same disease on our tomatoes each and every season.

This disease is early blight. Early blight occurs in home gardens and in our local farm fields every year. If you notice the same problems with your plants every year, this is the most likely culprit. Early blight starts at the bottom of the plant with some dots on the leaves, followed by yellowing of these lower leaves. The fungus overwinters in the soil and on any plant material which was not cleaned up after last season’s harvest.

This disease is “splashed” up onto the plant by rainfall and improper watering practices. Pruning or picking off infected leaves early can help slow the spread up the plant. Slowing early blight also saves upper leaves and fruit from sun scald because blights tend to defoliate the tomato plant late in the summer.

Preventing the disease takes planning. In spring, proper staking and mulching is important. Staking keeps the fruit off the ground. Mulching can be very helpful to prevent the splashing effect where the rain splashes the disease from the soil to the plant. Mulching also helps keep the soil cool – because tomatoes can generally not set fruit when the temperature gets above 90 degrees later in the summer.

Increased air flow around the bottom of the plant can also slow the spread of this disease. Prune bottom leaves touching the ground/mulch. Thin the plant at the ground level to allow more air movement. Prune out suckers and other shoots to reduce heavy amounts of foliage (without exposing fruit to full sun).

Although you may do a great job cleaning up plant material in the fall, you may still have early blight. Thus, preventive practices should be continued every year. Read more about this disease, here: http://go.osu.edu/earlyblight

NOTE: Do not confuse this disease with late blight, which usually starts at the top of the plant with large lesions turning purple or black. High humidity creates ideal conditions for this disease.

Eric Barrett is OSU Ext. educator for agriculture and natural resources in Mahoning County. Call the hot line at 330-533-5538 from 9 a.m. to noon Mondays and Thursdays to submit your questions.

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