Farm Horizons, June 2014

Common cucumber diseases

If your cucumbers are wilting and dying then you most likely have bacterial wilt. It can also occur in muskmelons, squash, watermelon, pumpkins, and gourds.

The first symptoms you will notice will be discoloration called bronzing (yellowish to olive brown) and limpy or droopy individual leaves, then the leaves next to them, and eventually the entire vine. The only solution of cure to this disease is to destroy the plant.

The best way to tell if you have bacterial wilt is this recommendation by the University of Minnesota: Cut the troubled stem or squeeze the cut ends lightly. Place the two cut ends together, and then slowly pull them apart. If a string of sticky ooze develops between the two cut ends, it is almost certainly bacterial wilt.

If you still are not positive, place the cut ends of an affected stem in a glass of water and wait 5-10 minutes. If the plant is infected, milky strands of the ooze will come out of the end into the water.

Mostly two insects – striped cucumber beetle and the spotted cucumber beetle spread bacterial wilt.

To control this next year, use resistant varieties to lessen the severity of beetles wanting to feed on your plants. Some resistant types are County Fair 83, Marketmore 70, Gemini F1, and Sweet Slice Victory.

Insecticide application is not recommended as you would have to spray continuously to even control them and this can also kill insects needed for pollination.

One thing you can do is to cover the row, which protects them until they flower. Once the flowers appear, then remove the covers, so other insects can access for pollination.

Row covers are made of various materials. Plastic and spun polyester are the most popular ones. Tests have shown that row covers keep pests out of the area as long as the edges are securely buried. Many nurseries and garden catalogs carry them.

Another way to deter is to use a 1/8-inch mesh netting which is available at fabric stores.

Anthracnose is another cucumber disease. The symptoms of this are when the culprit invades the leaves small yellow water-soaked spots develop. These areas then enlarge and turn brown and shatter. Some infected fruit has sunken black circular spots. To prevent this, plant on well-drained soil and rotate your crops.

Powdery Mildew is another disease many plants including cucumber get. This is easy to tell as there is white growth on the upper leaf surface, and then these areas turn brown and die. The plant gets weak and produce ripens prematurely. Fungicide works best for this, but remembers to apply again in 10 days.

Mosaic Virus is a very common disease for cucumbers. If a seedling becomes infected, they turn yellow and die. Older plants have distorted leaves and curl downwards. There are white blotches mixed with dark green spots that rise into easy to see blisters. The fruit is bitter and gets soggy. This virus lives in the roots of these plants over the winter. To control this disease you need to make sure the area is weeded as this virus survives in the plants.

The best tips for healthy cucumbers are:

• Be sure the area is weeded to keep the air moving.

• Mulch to prevent splashing of rain against the leaves.

• Rotate your crops every year.

• Deeply plow or burn any debris after harvest.

Growing cucumbers along a fence or panel makes them so much easier to pick and they do not seem to get as many diseases.

Check your garden daily to make sure that there are not new pests. Use insecticides carefully and according to the directions. You have to make sure you have the correct diagnosis before you can do any treatment. I recommend that you go to a dependable book or website such as www.extension.umn.edu and search the Yard and Garden Line.

Keep those questions and comments coming. Christine Schlueter, 19276 Walden Ave., Hutchinson, MN 55350 or e-mail rcschluete@yahoo.com

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