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Dear Mother Nature, Please don't send an early frost

By Janet Kubat Willette

Date Modified: 08/30/2013 12:53 PM

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MANKATO, Minn. – Crops need frost to hold off until mid-October, a DuPont Pioneer account manager said Aug. 20.

Jay Zielske gave a plot tour and talked about crop conditions during the celebration of the company's $2.5 million expansion at the Mankato Research Station.

The corn plot was planted May 15. It was the earlier of two planting windows in the month of May in south central Minnesota. The other planting window was around May 30, he said.

Corn planted May 15 is 136 growing degree units behind normal, Zielske said, translating into six to 10 days behind.

Nothing is in the dough stage yet. Thirty to 40 days are needed for corn to reach normal psychological maturity.

"So we need frost to hold off for a while," he said.

Everything pollinated quite well, but the latest maturity hybrids are showing a tip back that he attributes to those good sleeping nights.

On Aug. 19, Zielske drove from Mankato to Olivia. He saw a whole range of crop conditions on the trip. In Nicollet County, crops are showing dry weather stress, he said. In Renville County, crops are looking a lot better and more consistent.

In the Mankato area, they could use a shot of rain, he said.

There are few pest concerns with corn this summer, though there are isolated corn root worm concerns. Leaf rust and common rust are out there, but they haven't progressed much.

There is less incidence of Goss's wilt compared to the last two to three years, likely because Goss's wilt is a bacteria that enters through injury to a plant and conditions haven't caused plant damage this year. In areas with hail damage, Goss's wilt may show up.

Aphids are reaching threshold or have exceeded threshold in many soybean fields across the region. Usually, farmers spray aphids the last week of July and first week of August, with most spraying done by the third week of August. This year, spraying was delayed about a week.

Soybean aphids are also more variable this year, Zielske said. Infestations stayed low in early planted soybeans and didn't require insecticide applications.

However, later planted soybeans were more attractive to aphids and have required treatment.

Zielske said he hasn't seen any sudden death syndrome yet, but he expects to see it in the next two to three weeks as conditions in the early part of the growing season favored SDS. Brown Stem Rot may also show up in the next few weeks.

He encourages farmers to get out into their soybean fields and dig roots to check on their soybean cyst nematode population. Zielske said nematode populations are increasing, even when resistant varieties are planted. Populations can shift.