IPM STUFF 2023-5
This newsletter and the advice herein are free. You usually get what you pay for.
Crop weather
Rainfall, air and soil temperatures, degree-days, soil moisture, and other current and historical weather data for the University of Minnesota Southwest Research and Outreach Center (SWROC), a little spot about two miles west of Lamberton, MN, can be found at https://swroc.cfans.umn.edu.
Some of the earliest planted corn and small grains are emerging. Soybean planting ranges from none to nearly complete depending on the field conditions in an area.
For many in southern Minnesota, planting was brought to a stop by rainfall on Monday and Tuesday - heavy rainfall for some and it looks like more is on the way. After the 2022 drought, we needed the soil moisture recharge but unfortunately, it is too early to drown any corn rootworm larvae.
Alfalfa
Alfalfa weevil adults began moving into alfalfa at the SWROC over the past weekend. As predicted earlier, it looks like populations will be as high or higher than 2022.
Degree day models to predict alfalfa weevil development are available at https://vegedge.umn.edu/alfalfa-weevil. For several reasons, the model is not perfect, particularly later in the season. Note: Other insect development models are available at this site as well.
Small Grains
Aster leafhoppers have arrived but as of May 5, populations were low. Your mileage may vary.
Most true armyworm pheromone captures in southern Minnesota have been low to moderate. The higher captures have been in SC and SE Minnesota. Watch for this insect later this spring and early summer.
I have not yet found cereal aphids in winter cereals. I suspect I will find a few once it dries enough to get back into the field.
Corn
A consultant sent a picture of a caterpillar for ID. It was most likely a European corn borer. The larvae overwinter and pupate in the spring. The univoltine (single generation) biotype needs to accumulate more degree days to pupate than does the multivoltine. Because of observations of Bt resistant corn borer in Canada, it is important to recognize signs of corn borer injury, even when scouting Bt hybrids. Degree day development models for corn borer are available.
Pheromone traps have captured enough armyworms to encourage scouting corn planted into a winter cereal cover crop. Stay tuned.
Black cutworm pheromone trap captures have been mostly low this spring. Significant captures occurred in Rock and Martin Counties. Eggs should be hatching now. Leaf feeding on crops and weeds by small larvae is an early clue to the presence of cutworms. Include cutworm species, other early season stand-reducing insects, and diseases when evaluating corn stands and weeds.
Soybean
Seedcorn maggot fly emergence is one of the insect degree day development models available. Soybeans planted into manure/green manure when flies are active are at some risk for stand loss.
Soybean aphid eggs should be hatching as buckthorn buds have opened. 2023 populations will depend, in part, on how successfully they make the move to soybeans and in part growing season weather.
Keep up date on pest development.
Degree day development models and blacklight insect captures are available at https://vegedge.umn.edu/weekly-moth-flights
Keep up to date on cutworm and armyworm observations at https://swroc.cfans.umn.edu/research/ipm/bcw-network
Corn growing degree day models along with temperature and precipitation maps can be found at the Midwest Regional Climate Center https://mrcc.purdue.edu/
Happy trails,
Bruce