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WEEKLY UPDATES |
Weekly Soybean Field Crop Report - July 25, 2007
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Posted on
July 30, 2007 at 14:08:28
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Soybeans
Soybean aphid populations continue to increase in specific hot spots, while the bulk of the province remains well below threshold numbers. Aphid numbers have surged over threshold in some fields in eastern Ontario, adding this region to the list of hot spots. In areas where populations surged over threshold early in the season, requiring early control, populations have rebounded rapidly, and rebounded again, with some fields now needing control for the third time. Continue to scout and monitor populations closely in all soybean fields!
Root rots are more prevalent in many fields this year. Dead plants occur as either a few in a row or as patches in area field. Root rots are not expected to be an issue under dry conditions, but with no moisture, and a lack of root growth and development, plants have succumbed to these diseases. Select varieties with resistance and use cultural practices to reduce soil compaction, and improve soil structure and drainage to minimize problems from these diseases in the future.
Soybeans intended for identity preserved markets require field walks to ensure quality standards are met. Weeds such as nightshade and pokeweed are of particular concern, as a few of these plants can cause severe staining of beans. Tolerance to corn in IP soybeans or edible beans at harvest is zero. Rogue fields for any off types. In IP varieties that have a grey pubescence (hair on the stem), off types with a tawny pubescence should be removed.
Soybean cyst nematode (SCN) continues to extend its area of infestation from the south-west into western Ontario, and has now been confirmed in eastern Ontario as well. When scouting fields pay particular attention to stunted, yellow plants. SCN damage is often confused or misdiagnosed as potassium deficiency, herbicide injury, compaction or root rot damage. Never pull up the plant to see SCN. The nematodes will be stripped off as the roots are pulled through the soil. Dig up the plant and wash the roots carefully, look for small white cysts the size of the end of a pen. Under good growing conditions visual damage from soybean cyst nematode may go unnoticed. Manage using crop rotation and resistant soybean varieties. For further information refer to the OMAFRA soybean web pages http://www.omafra.gov.on.ca/english/crops/pub811/4scn.htm or the Agronomy Guide (pub. 811).
-Submitted by Horst Bohner, OMAFRA Soybean Specialist
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