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Princeton, MN | I disagree, in central mn we have been watching the aphid count carefully for the last 3 weeks. We have yet to see an increase in population above 100 per plant, the multicolored ladybird beetles have been doing their job as well as the other beneficials in keeping the numbers down.
How do you figure you have lost the war at less than 250 per plant?
I agree with getting the equipment and insecticide lined up, which was done when we saw the first ones, but after listening and getting to know one of the foremost aphid experts in the world, I fully believe the 250 economic threshold. The economic injury level is around 650 per plant according to the university of minnesota, the threshold is set at 250 to give time for application before the injury level is reached. The real EIL is actually around 4000 cumulative aphid days, which is the equivalent to 200 aphids per plant with no reproduction for 20 days, or 1 aphid on a plant for 1 day=1 cum. aphid day.
I believe that the excessive use of pyrethroids will lead to major resistance problems in the sb aphid. As you most likely know, when on the soybean aphids assexually reproduce, so they basically clone themselves. If one becomes resistant, all of its offspring will be as well, where an insect that reproduces sexually has different alleles present and they can get the susceptible gene in the offspring.
There is enough trouble with herbicide resistance from the overuse of glyphosate, lets not do the same with insects. | |
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soybeans, Aphids and insecticdes-OSU update, warning
