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Extension > Minnesota Crop News > August 2015

Monday, August 17, 2015

Updated forecasts of corn yield and maturity available for the Corn Belt

by Jeff Coulter, Extension Corn Specialist

Much of the corn in Minnesota is in the milk stage. Soil moisture levels and air temperatures for much of the corn in Minnesota have been favorable since pollination, but some regions have become dry.

Stress due to dry conditions through the end of the milk stage can reduce grain yield by reducing the number of kernels per plant. After the milk stage, kernel number per plant is set and kernels become doughy. Stress occurring between the dough stage and maturity reduces grain yield by reducing kernel weight.

Friday, August 14, 2015

Aphids in corn: The dilemma of post-pollination infestations

Bruce Potter, IPM Specialist, and Ken Ostlie, Extension Entomologist

As agriculturalists re-enter corn fields to scout corn rootworm beetle populations and begin to estimate yield potential, they often find some unwelcome aphid visitors. Heavy infestations on ears and adjacent leaves can grab your attention and trigger the “Should I spray question?” The crop protection urge may be strong with the corn crop we have this year; let’s review what’s known about aphids in corn before you make that spray or don’t spray decision.

Thursday, August 13, 2015

Treating late-season soybean aphids


by Robert Koch (Extension Entomologist), Bruce Potter (IPM Specialist) and Ian MacRae (Extension Entomologist)

Late-season management of soybean aphids can be challenging. There have been many winged aphids colonizing fields over the past couple of weeks. Furthermore, the forecasted weather conditions will be excellent for aphid population growth.  Fields that were seed treated with insecticide and those treated early with insecticides tank-mixed with herbicide or fungicide are not immune to infestation. Those early-season prophylactic applications of insecticide do little to prevent soybean aphid populations from reaching damaging levels later in the season. Here, we provide an overview of late-season scouting and management recommendations for soybean aphid.

Tuesday, August 11, 2015

Take advantage of window to control weeds following small grains harvest

by Dr. Tom Peters, Extension Sugarbeet Agronomist, Dave Nicolai and Doug Holen, Extension Crop Educators
weed-flush-after-sm-grain-harvest
Figure 1. Weed flush after small grains harvest.

Recent travel across Minnesota highlights that it is small grains harvest time. Thrashed fields have a clean look, especially from the highway. However, closer examination reveals a great number of weeds, especially waterhemp, emerging from the stubble. More swathing due to uneven harvest maturity and significant lodging resulted in weeds getting a head start this season.

Wednesday, August 5, 2015

What to consider when treating a soybean field more than once for soybean aphid


by Robert Koch (Extension Entomologist), Bruce Potter (IPM Specialist), Ian MacRae (Extension Entomologist), and Ken Ostlie (Extension Entomologist)

Soybean aphid populations in many areas of Minnesota are increasing. This year, there are a number of factors making population development and management less predictable than in the previous couple of years:
  • Late summer dispersal of soybean aphids is currently occurring, bringing high numbers of winged aphids to colonize fields; sometimes those that were previously treated.
  • Forecasted weather conditions for the upcoming week look favorable for aphid population growth.
  • A number of fields in southwestern Minnesota have reported unexplained failure (poor performance) of recent insecticide treatments and will require additional applications to control existing populations.
All of these factors point to the importance of weekly scouting for soybean aphids and treating when populations reach the threshold of 250 aphids per plant when 80% of plants have aphids (U of MN guide to soybean aphid scouting). At the threshold, yield loss is not yet occurring, but will if aphids are not soon controlled.

Monday, August 3, 2015

Corn development and updated yield forecasts for the Corn Belt

Jeff Coulter, Extension Corn Specialist

Much of the corn in Minnesota has finished pollinating and kernels are in the blister to milk stage. Soil moisture levels and air temperatures for much of the corn in Minnesota were favorable during pollination and continue to remain favorable, but some regions are becoming dry.
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