Unfortunately for areas like the Northern Plains, which have experienced two consecutive dry seasons, farmers could be on the verge of a serious outbreak of this fast-moving defoliator.
“If we have another hot, dry spring, we’ll have lots of grasshoppers,” MacRae warned, noting that many egg laying occurred in the fall in northwest Minnesota and in the northern River Valley. Red River.
“There are a lot of eggs there, and we had good snow cover and they’re also deep enough in the ground not to be affected by the low temperatures we’ve had this winter,” he said. he adds. “So if we have a dry spring, we’ll probably have a successful hatch.”
Learn more about the University of Minnesota grasshoppers here: https://extension.umn.edu/…
TWO-SPOTED SPIDERS AND APHIDS
Soybean aphids can do well in hot, dry conditions, but they come up against natural limits. They love heat and will speed up reproduction in temperatures ranging from 75 to 80 degrees. But they slow down when temperatures reach 90 degrees, and in severe drought colonies will suffer, noted University of Minnesota IPM extension specialist Bruce Potter. As soybean leaves turn upside down to try to conserve water during the scorching afternoon hours, they expose aphids trying to shelter on those undersides, he noted.
The real key to a successful soybean aphid infestation is in the spring, when aphids move from their overwintering habitat in buckthorn plants to soybean fields. If they experience hot, dry conditions at the time and find decent soy covers, they can take off, Potter noted.
“Usually by June we have a pretty good idea of how good this move into soybeans is,” he said.
In long, hot summers, aphid and mite infestations can overlap and grow together, Potter added. “You could start with soybean aphid issues and then move on to spider mites,” he said. “And in my experience, spider mites usually win.”
This is because spider mites love a good late summer roast. As temperatures reach 75 degrees, it takes just five days for a hatched mite to become an adult. They also promote crisp dry air levels in the oven, MacRae said. “The mites actually prefer to breed because it gets drier,” he noted.
Heat also helps mites and aphids by interfering with naturally occurring fungi in the field that feed on insect pests, MacRae noted. “Fungal diseases that control insects are reduced, so you get a larger starting population,” he explained.
Carefully monitor spider mite populations as crop fields approach reproductive stages, Potter added. “Once these plants are in the reproductive phase and facing hot, dry weather, that’s when things really take off,” he warned. The mites make camp in the canopies of soybeans and suck sap from the leaves, leaving a bronzed, speckled appearance.
See more on the two pests here: https://extension.umn.edu/….
You can find an archived version of this University of Minnesota webinar here: https://extension.umn.edu/….
Emily Unglesbee can be reached at [email protected]
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