Time is Up for Soybean Aphid Spraying

My friends, it is now R7 in most of South Dakota.  Soybean aphids numbers have
declined dramatically as the soybean plants senesce (yellow).  You had 6-8 weeks
to do something about the aphids, and, hopefully, you followed our recommendations.

Buford says shame on you if you followed the "other" threshold espoused by so-called
"major" universities.  Hard to believe that 39 aphids are no aphids!  Must be invisible
in those fields, or, a new way of counting that starts with the back forty. . . .  Not sure.

                                                 

I'm pretty pleased with the aphid infestations in our plots.  All seed treatments and
sprays will be tested this season.  When we sprayed our plots at R2-R3, the aphid
numbers were less than 10 soybean aphids per plant with about 10% of the plants
infested.  And, we knew how to count - 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 - just like anyone with
a Ph.D. degree does (except gophers).

At R5 (August 22), the numbers in the untreated plots were 160 per leaf.  And on
the average, there were 60 leaves per plant in the variety that we planted.  That
translates into 9,613 aphids per plant in the untreated plots, not even counting the
aphids on the pods and stems.

We have over 500 plots in our soybean aphid research sites between Brookings
and Beresford.  I need volunteers in counting the (now frozen) aphids!

Brand New! Stage specific economic injury levels for V5, R2, R4, and R5             

                                      

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 Web Posted on Thursday, August 11, 2005 by Mike Catangui. Last Updated on Tuesday, September 20, 2005.