MSU Field Crop Advisory Team Alert newsletter

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Field Crop Advisory Team Alert newsletter

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Vol. 21, No. 11, June 22, 2006

Is it spider mite? NO! Christina DiFonzo Entomology


Samples of V2 soybean were sent in to Diagnostic Services with a yellow marginal "flash" and reddish-brown spotting. There were no pathogens or insect pests found associated with the symptoms. This particular field was sprayed a few days prior with glyphosate plus a manganese formulation. While certain manganese formulations can reduce the effectiveness of glyphosate, glyphosate can also have a chelating affect in young soybean leaves. Manganese can be "tied up" resulting in temporary marginal to interveinal yellowing, especially in soils with marginal manganese content and slowly growing soybeans. The reddish-brown spotting on the leaves was attributed to one of the fertilizer-containing products added to the tank. See the article in this issue of the Field Crop CAT Alert on recommendations of manganese formulations by Kurt Thelen.

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