Master Gardener: Threshing show and tomato problems go together

By Jerry Vitalis, Chisago County Master Gardener

One of our favorite events is the Almelund Threshing show that will be held Aug. 10-12. Every year we average more than 400 garden questions, most of which we can answer, but some must be researched.  Last year it was Japanese Beetles, the year before it was Emerald Ash Borer, but every year tomato questions are high on the list.

Weather is the main factor in raising tomatoes.

While tomatoes like hot weather, the extreme heat has been hard on them. They also like moist conditions so the hot, humid weather invites fungal diseases.

Fusarium wilt is a warm season fungal disease that only attacks tomatoes.  The lower leaves will turn yellow, and the yellowing is often confined to one side or the other of the midrib.  Continue to remove the infected lower leaves to combat the problem.  Mulch the plants to keep the roots damp and cool.  Mulching also prevents soil from splashing up onto the lower leaves, which can transfer soil-borne diseases.

Another potential problem this summer could be early blight.  The symptoms include leaves and stems that develop large dark spots with each spot having many narrow concentric rings.  Similar dark, sunken blotches also appear on the frit, usually beginning at the end of the stem.  Again, the only thing that seems to help is to remove infected leaves to prevent spreading.  There may be some home remedies that work, like fungicides that may help control the disease.  If they work and are safe, go for it.

If you get through the summer without any more problems, you may have to deal with the late blight.  This is the same blight that caused the Irish Potato famine in the 1840’s.  The problem then was that they only had one variety of potato in Ireland, while now we have many varieties of potatoes and tomatoes. The late blight likes cool, rainy conditions. Verticillium wilt is a cool season fungal disease that attacks tomatoes, potatoes, eggplant, strawberries and raspberries.

Blossom end rot, catface, septoria leaf spot, and other tomatoes disorders are affected by extreme weather and moisture conditions.  Hopefully, we can help you through some of these concerns at the Almelund Threshing Show. Visit us in our pioneer building at the east end of the Threshing Grounds.

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