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October 2000 |
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Two Soybean Problems |
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Soybean Problems Jim Jarman |
Autumn, harvest or shortly thereafter, is the ideal time to sample for the presence of nematodes. The tiny plant-parasitic worms often reach their highest levels at the end of the growing season. Sampling now can increase the chance of detecting the presence of these nematodes, especially when they are present at low levels. There are no rescue treatments for plant-parasitic nematode infestations during the growing season. Also, the most common symptom of nematode damage is yield loss, which cannot be measured until harvest. Visual symptoms of soybean cyst nematode (SCN) are usually not seen unless the infestation is extremely high. The disease, sudden death syndrome (SDS), may signal a SCN infestation but other factors are typically involved. Crop rotation and the use of resistant varieties are the best management for most plant-parasitic nematodes. It is crucial, therefore, to test for the pest well before planting. The soybean cyst nematode, the number one pest in soybeans, can bring about dramatic yield losses in nonresistant varieties. Soybean fields can be tested anytime after harvest until planting, but timely sampling allows for greater flexibility in seed selection to reduce yield loss. Cornfields should be tested for lesion, lance and root knot nematodes as soon as possible after harvest, and they should be tested for needle and sting nematodes within a month of planting. More information on nematode sampling and management can be found in University of Missouri Guide sheets G4450 Soybean Cyst Nematode: Diagnosis and Management and G4452 Soybean Disease Management from the Callaway County Extension Center. Information for this article is from Pat Donald director of the University of Missouri Extension Nematology Laboratory at (573) 882-2716. Store immature soybeans or feed to cattle and pigs Dry August weather, combined with above-normal temperatures, left some soybean fields with too little water to reach maturity naturally. This was especially noticeable in southwest and west central Missouri. If Callaway County farmers find soybeans that are still green and immature, they may not be accepted well especially in the current market. They have been receiving the designation 'sample grade' accompanied by large discounts. Green soybeans produce "off-color" oil and often fetch more than 50 cents less per bushel than fully mature beans. Although storage problems can occur with poorly developed beans, holding the soybeans for a while may reduce the large discounts that is more likely right at harvest.. It is recommended that immature soybeans be stored only in aerated bins, with moisture content no higher than 11 percent. Green soybeans should store OK as long as they are dry. Unfortunately, the green color will probably not disappear during storage Immature beans also have their place in animal diets. Marcia Carlson, a swine nutritionist with the Commercial Agriculture Program at the University of Missouri, has found that whole soybeans can be substituted for up to 25 percent of the usual soy component in diets for growing to finishing pigs and can completely replace the soybean-based component in gestating sows. Raw, immature soybeans work especially well in the energy-limited diet of gestating sows. Other University of Missouri animal scientists have also determined that immature soybeans can be substituted for other soy-based feeds in the diets of growing and reproducing beef cattle. Cows on hay or grazing poor quality pastures can also benefit from soybeans in the diet. Overall the best use of immature soybeans is probably as a full-fat component for some livestock. While oil and protein contents may be somewhat smaller than for normal mature soybeans, the total nutritional value is still quite high. Information for this article has come from Bill Casady, University of Missouri Commercial Agriculture Program Agricultural Engineer (573) 882-4370
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