Most southern Minnesota corn crops are well into dent stage and will probably reach R6/black layer during early September, reports technology manager Joel Johanningmeier. This year’s corn crop is progressing two to three weeks quicker than last year because of more accumulated growing degree days and heat units.
Soybean plants are fully podded. In the coming days, some soybean fields will start to yellow and drop their leaves, says Johanningmeier, adding that this year’s soybean growth progress is similar to that of last year. Diseases are starting to emerge in soybeans and include some white mold. Also present is sudden death syndrome (SDS), which is not very widespread in the southeastern part of Minnesota but is getting more prevalent as it moves farther west and north.
Johanningmeier hasn’t noted any widespread outbreaks of corn insects, but he has seen some slugs, corn rootworm and corn aphids in various corn plants. Farmers should especially evaluate crops for corn rootworm feeding. As for soybean insects, he’s seen some spotty aphid pressure but, more importantly, he’s observed Japanese beetles. They have caused some defoliation in soybean plants, most of which was not at a treatable level. However, if farmers were spraying for aphids, they were probably also taking care of any Japanese beetle problems.
Cornfields that received sidedress nitrogen applications are looking good, while some that did not because of wet weather are yellow. He has seen some potassium and sulfur deficiencies in corn as well.
Johanningmeier urges farmers to evaluate the health of their corn plants and recommends doing stalk push tests to ensure plants are remaining upright. He also recommends that farmers establish a harvest schedule. Farmers who anticipate harvesting their soybeans ahead of their corn will need to ensure their corn stands that much longer. Soybean farmers should assess what their disease pressure was this year and use that information to select varieties that are either resistant or tolerant to those diseases for next year.