NDSU Extension - Ramsey County


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July 9, 2012 Agriculture Column


The weather is warming up and will not take long to dry things out again.  Thank goodness for the rain we had last week.  We could not have asked for a better rain than what we received.  The crops are looking good for the conditions we have had and there is fields of Barley turning, meaning harvest is not far away for the spring planted crops.  The winter wheat does look good but concerns for the fields that had a fair amount of Stripe Rust.  I hope those fields were managed to stop the spread as it can cut yields tremendously.

Spider mites in Soybeans
We've been getting calls about spider mites in soybeans, not surprising given our high temps and the dry conditions in some locations.  As temps get into the 90's, spider mite reproduction and development rates increase significantly.  Drought also exacerbates spider mite populations, and when drought conditions are relieved by rain, spider mite populations may not necessarily decrease.  Consequently, even after drought conditions pass, best to continue scouting for spider mites damage.

Spider mites are tiny and only large females are visible to the naked eye (unless you've got really good eyesight!).  The best way to see spider mites is to shake a plant over a piece of white paper - any moving pieces of dirt are likely spider mites...  So to scout for something that small, it's best to look for damage.  Spider mite damage will first appear as small yellow spots (stippling) on lower leaves.  There is currently no solid treatment threshold in soybeans, but If stippling reaches mid-canopy leaves, a treatment is likely necessary.  Pyrethroids may flare spider mite populations, spreading mites and increasing their populations.

A good source for information on spider mite biology, scouting and thresholds was prepared last year by Bruce Potter and Ken Ostlie and is available at:



July 12             Relay for Life Garden Tour

July 17             Carrington Extension/Research Center Field Days

July 19             Langdon Extension/Research Center Field/Canola Days

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