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Published May 21, 2012, 08:42 AM

Bugs, weeds pose special threat

Area farmers welcomed the mild winter and early spring that allowed them to make rapid planting progress. But the favorable weather carries a downside: weed and insect problems not encountered in a typical growing season are popping up, and the arrival of normal weed and insect issues is accelerated.

By: Jonathan Knutson, Agweek

Area farmers welcomed the mild winter and early spring that allowed them to make rapid planting progress.

But the favorable weather carries a downside: weed and insect problems not encountered in a typical growing season are popping up, and the arrival of normal weed and insect issues is accelerated.

“It’s a double-edged sword,” Ian MacRae, an entomologist with the University of Minnesota Extension Service in Crookston, says of the advanced growing season.

Farmers in the region have two challenges, he and other experts say:

• Checking for, and potentially dealing with, troublesome weeds and insects earlier than usual in the growing season. For instance, alfalfa weevils have been spotted in western South Dakota, and their larvae are expected to be active — and damaging plants — several weeks earlier than normal, according to South Dakota State University Extension.

• Dealing with insects and weeds that normally aren’t a concern.

For instance, astor leafhoppers — seldom a problem on most of the Northern Plains — are popping up in North Dakota, Minnesota and South Dakota.

Mild conditions this winter helped more of the insects survive into spring. Further, the insects were able to feed on more-advanced-than normal crops, MacRae says.

The early spring also can exacerbate existing weed and insect issues.

For instance, water hemp — “the most satanic weed there is” — becomes an even greater threat because of the extended growing season, says Rich Zollinger, North Dakota State University Extension Service weed specialist.

Keep in mind that all pests weren’t affected equally by the dry, mild winter and early spring.

For instance, insects that overwinter above ground benefitted much more than insects that overwintered below ground, according to information from SDSU Extension.

Scout early this year

Farmers’ biggest job on the weed, insect and crop disease front may be remembering that problems will occur sooner than usual this year.

“Things are just moved up this year,” says Mark Rosenberg, agronomy weeds field specialist with SDSU Extension’s regional office in Brookings.

If a farmer normally encounters a particular pest in, say, early June, they better not wait until then to begin scouting for it, experts say.

In short, a crop’s level of maturity, not the calendar, will dictate when pests and crop disease could become an issue this growing season.

One thing that hasn’t changed this year: weather conditions during the growing season will play a huge role in how serious problems ultimately become.

For instance, the dry, mild winter bolstered the chances that grasshoppers could do major damage in most of Montana and parts of western South Dakota and western North Dakota.

But grasshoppers don’t handle moisture well, and substantial rains this summer would greatly reduce the damage that the insects do, MacRae says.

‘Weed of the Year’

Area agricultural producers need to be particularly vigilant of waterhemp, which is pegged as “Weed of the Year” in NDSU’s 2012 Weed Control Guide, Zollinger says.

“People need to understand just how evil this weed is,” Zollinger says.

Waterhemp emerged earlier than usual this year, increasing its already high danger potential, he says.

Among waterhemp’s many negative characteristics: it can produce up to 5 million seeds per plant and it can become resistant to glyphosate.

Glyphosate is a widely used, broad-spectrum herbicide. It’s sold under several brand names, the most prominent of which is Roundup.

Waterhemp also is resistant to widely used ALS herbicides.

Waterhemp is controlled best by a combination of pre- and post-emergent herbicides, according to information from NDSU.

To learn more about waterhemp: ww.ag.ndsu.edu/ weeds/weed-control-guides/nd-weed-control-guide-1.

Extension officials in several other states also offer online material on waterhemp.

“We need to fight this as hard as we can,” Zollinger says.

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