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| Tomato early blight developing on lower leaves. Leaves first yellow, develop spots, wither die and progress through the plant. |
For disease control I follow the progression of ....Prevention, then Management, then Organic Disease Prevention and Conventional Disease Control last.
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| Tomato early blight developing on tomato leaves |
I am seeing the yellowing of tomato foliage and the development of dark Brown or grey spots on the leaves. This is followed with leaf death, shriveling, dying and turning crispy.
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| Grey spots first develop on yellowing leaves |
Early blight starts out with the lower leaves and stems of the tomato plant turning yellow or mottled yellow. Soon, these yellowing leaves develop grey spots on the margin or center of the leaves which cause these infected areas to die. These dead spots are now brown and commonly have concentric rings inside these brown spots.
Not all of the spots will make obvious concentric rings. But I search through all of the spots looking for these concentric rings and if I find them I can conclude it is the disease called Early Blight.
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| Remove infected foliage from the plants. Stop overhead watering. |
If this disease is developing on your tomatoes you must get it under control immediately before it spreads.
Do this NOW!
Remove the innoculum. First, using a sharp scissors or pruners clip off all of the yellowing foliage back to the stem and remove it from the garden. This is a source of infection for new growth.
Stop spreading the disease. Second, if you are watering and spraying the foliage with water in any way, STOP DOING THAT! Wet foliage spreads the disease. Always water the soil, not the foliage or leaves. Periodic washing of the foliage is okay but do it only once in a while and make sure it is early enough in the day and the temperatures are hot enough to dry the foliage thoroughly before it cools in the evening.
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| Neem Oil 70% concentrate at Viragrow for $22 a pint |
Change the environment. Third, if your tomatoes are large and bushy so that sunlight cannot penetrate inside the canopy and air cannot move through the plant to dry the foliage, thin out plant foliage. This decreases the humidity, opens the canopy for more light which strengthens the plant's interior growth. This disease LOVES wet surfaces and high humidity. It stops advancing in strong sunlight, dry conditions and healthy plants that can ward off the disease.
Prevent the disease from advancing. This is where chemicals come into play. First are the organic types.
There are several organic options you can choose from for foliar sprays: Neem oil (yes, it controls some disease as well as some insects), Seaweed Extract, Compost Tea, baking soda in water are a few. If you want to go the organic route and you cannot find rates or methods of application, contact me and I will get them to you.
Viragrow has Neem Oil, Seaweed Extract and Viragrow's own Compost Tea. We have our compost available in brew bags for your own brewing or liquid tea available if you notify us 24 hours in advance. Brew Bags are are $0.50 each and will make one gallon of fresh, sprayable compost tea. Make sure you use compost tea that is fresh for best results.
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| Cold pressed Seaweed Extract at Viragrow $3.80 per pint or $28 per gallon |
Nonorganic chemical control of early blight. Fungicides are used to keep the disease from getting worse. They will not correct the disease which is already present.Nearly any of the fungicides for vegetable gardens will control this disease. Viragrow does not carry any conventional plant disease products but you can pick them up at any local nursery or garden center. Remember, these are not organic control methods and should be a last resort.
Other things you can do:
Use certified organic seed or sterilize the seed you use. This disease can be brought in to your garden from the seeds that were used when your tomatoes were grown. If you are starting your own plants from seed next planting season, place your tomato seeds in 140F water for 25 minutes. Make sure the temperature is no more or less than this. This kills the disease organism which can sometimes be on the seed itself unless the seed is certified organic.
Remove infected vines from the garden. Using infected vines as a mulch or soil amendment will make the disease problem worse. Do not compost infected vines.
Grow your tomatoes, peppers and eggplant in different areas of the garden each year. This is called "rotating" your vegetables. This disease can live in the soil. Moving your vegetables to new locations each year helps to reduce this disease problem. You can grow them in the same spot again in 3 to 4 years.
The document below is an excellent source from e-Extension on organic methods used for controlling early blight in tomato. You can access this document here or below.
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