Early blight is caused by a fungus that generally is first observed on older tomato plant leaves. The fungal spoors often are blamed as the cause of allergy episodes. However, many Alternaria fungi thrive in gardens and contribute to mold allergy problems that torment many Kentuckians.
There are a couple of more interesting things about tomato early blight.
Blight-infected tomato leaves develop circular brown spots and turn yellow before they shrivel up and die. The dark brown spots have concentric rings characteristic of this disease. If you closely look at the pattern, you'll notice each ring could represent a day's fungal growth on the leaf, much as tree rings signify age in years.
Let's talk about how to control this devastating disease in our tomatoes. First, remember that because early blight is a fungus we can't cure it once we get it on our plants. Can slow the disease down but the key to controlling early blight is to spray a protective fungicide before we get the fungus on the lower part of the plant. The fungus is always present in the soil and most of the time it infects the plants by rain drops splattering on the soil surface and carrying the fungus up on to the lower leaves of the tomato plant. Mulching with straw or grass clippings can help protect the plant from infection and caging or staking to keep the plant up off the ground can be a tremendous help as well.
The fungicide of choice for home gardeners is Daconil (active ingredient: chlorothalonil), Follow the label directions, and a general purpose insecticide such as malathion can be mixed with the fungicide at the same time so you can control any insect problems that you might have. Spray every 10 to 14 days starting three days after planting. This spray program will help keep early blight under control and from destroying your tomato crop.
For more information on tomato early blight or other garden or field crop diseases, contact the Boyle County Cooperative Extension Service.
This week's joke
A truck driver was driving along on the freeway. A sign comes up that reads, "low bridge ahead." Before he knows it the bridge is right ahead of him and he gets stuck under the bridge.
Cars are backed up for miles.
Finally, a police car comes up. The officer gets out of his car and walks around to the truck driver, puts his hands on his hips and says, "Got stuck," heh?"
The truck driver says, "No, I was delivering this bridge and ran out of gas."
Jerry Little is Boyle County extension agent for Agriculture/Natural Resources.