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About four weeks after tr... #198903 - Ask Extension


About four weeks after tr... #198903

Asked July 13, 2014, 9:36 AM EDT

About four weeks after transplanting tomatoes from nursery pots to prepared garden soil it's leaves began to yellow and within a week the entire plant branch got yellow and soon dried up. I continued to pick off yellow and brown branches but each week the next branch on the stem went through this process. The plant Remains growing more with and creating flower blossoms. Is there a need to continue removing yellow/Brown branches? Is there any remedy to stop the progress f this condition? What effect will this have on my eventual yields of tomatoes? What steps might I try for 2015 growing season?

Stearns County Minnesota

Expert Response

Here is up to date information on early blight soil must not be allowed to splash/touch the leaves since blight spores are transmitted through the soil.

Dennis Mielke Replied July 13, 2014, 12:31 PM EDT
I see.  So now that blight has begun, how do I salvage the growing season?  I have remove numerous branches and individual leaves and removed them from the garden.  I covered all surrounding dir with dried grass clippings.  I tied up beaches to increase air flow between plants.
Is any foliage spray available to enable 3-4 foot high plants to provide a meaningful yield of tomatoes?
The Question Asker Replied July 16, 2014, 8:37 AM EDT
The posting above was made the original inquirer.  Thanks
The Question Asker Replied July 16, 2014, 5:41 PM EDT
Any infected material will remain infected so,, it is better to start with new plants
Dennis Mielke Replied July 18, 2014, 4:56 PM EDT
Thank you for your question.

From your description, your tomato condition actually sounds like it may be septoria leaf spot. According to our publication on this disease, "Symptoms usually begin to appear on the lower leaves after fruit set. Initially round, yellow spots develop. Later, these spots enlarge and turn brown to gray. Tiny black fruiting bodies (pycnidia) eventually form in the center of the leaf spots. These pycnidia produce spores which cause secondary infections, usually in an upward direction, throughout the plant. Heavily infected leaves turn yellow, then brown and fall from the plant. Exposed fruit, due to defoliation, may be damaged by overexposure to the sun (sunscald)." Source:

Once the plant is infected (whether septoria leaf spot or early blight as Dennis suggested), there's not a lot you can do for this year's crop. Just keep the plant watered well and pick the fruit as soon as it is ripe. When they are done fruiting, dispose of the plants.

Future crops: When growing tomatoes, start by selecting varieties that are resistant to disease. These are listed on the tag of the potted plant or the seed packet.

Second, sanitation is very important. Clean up fallen leaves and fruit and destroy. Clean tools, cages, poles etc. with a 10% bleach solution to avoid spread disease. Rotate your crop to avoid replanting tomatoes and other members of the nightshade family (potatoes, peppers, eggplant, tomatoes, tomatillos) in the same garden location year after year. Many tomato diseases are soil-borne meaning that they overwinter in the soil. Moving plants helps break the disease cycle. This could also include planting them in containers. If planting in containers, wash the container with a 10% bleach solution and fill your container with new potting soil. Mulching your tomatoes is a good general cultural practice as it prevents splashing of soil-borne pathogens onto the leaves. It also helps retain soil moisture.

U of MN Extension has an excellent diagnostic tool and subsequent publications on growing tomatoes in Minnesota. The article Dennis sent was a good place to start, and I encourage you to continue reading these articles on our Yard & Garden website:
You'll find tomato info as well as many other good resources and our diagnostic tools ("What's wrong with my plant?" , "Is this plant a weed?" and "What insect is this?") also on this page.

Best of luck to you and thanks for contacting Ask an Expert.
Julie Weisenhorn Replied July 18, 2014, 5:17 PM EDT

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