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AgAlerts 2002 From Griggs County
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Issue # 11, July 26, 2002
I am back from vacation and trying to get caught up with a weeks worth of mail. Since the last AgAlert, the crops have progressed considerably. One of the main problems is the rust is spring wheat. The variety Ingot seems to be hit very hard. The next two diseases that could cause problems will be white mold in dry beans and canola.
Sunflower beetle numbers are high again this year. Threshold levels are 10 to 15 beetles per plant and 25% defoliation. Confectionary growers have tried to time insecticide treatments to control both beetles and seed weevils. If this can occur, wonderful. But if defoliation is beyond threshold levels, seperate treatments might have to occur.
The characteristic symptom of this disorder is the slight or complete fusion of the upper part of the plant into a tight tube that encloses the upper leaves and tassel. The tube develops at the third to fifth node above the soil line, and is composed of thick and heavily lignified tissues that resemble a buggy-whip or an onion leaf. This disorder is often caused by growth regulator type of herbicides that include 2,4-D or Banvel.
Each year during tasseling we start to see
smut showing up on certain corn plants. Head smut rarely causes yield
losses but it does attracts your attention.
The causal fungus enters young seedlings and normally grows
internally throughout the whole plant as it develops, although sometimes parts
of the plant may escape infection. Ways of spread can occur during harvest
when kernels become contaminated with spores, one of the ways in which the smut
is spread to new areas. Spores can be spread locally by wind for up to
several miles. Spores are also soil-borne, and can be carried from field
to field by contaminated machinery. They also can be spread in
contaminated animal feed, and can pass unaffected through cattle. Spores
can survive in the soil for up to 10 years. Corn seedlings are infected as
they grow to the surface under relatively dry and warm soil conditions which
favor infection. Control lies in preventing dissemination of spores in
seed corn, feed, manure, and on farm machinery.
Samples of phytophthora rot have been brought into the office this week. This disease is a major soybean disease where soybeans have been grown for a number of years. The best control is variety resistance. Once this disease is established in a field, it persists for many years. For more information, click on the following link. Phytophthora root rot.
Please Contact Our Office For Additional Information
E-mail: griggs@ndsuext.nodak.edu
Go to the 2002 AgAlert Index Page