Integrated Crop Management News

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Drought and Derecho Increase Mycotoxin Risk in 2020 Iowa Corn Crop-Scouting and Monitoring Fields

September 9, 2020
Figure 1. The olive green, powdery mold that characterizes Aspergillus ear rot can be seen on this corn ear.  Photo courtesy of Alison Robertson.

The majority of Iowa is currently in moderate to severe drought, with west central Iowa under the most extreme drought. As if drought were not enough, we were dealt another blow with extreme and widespread wind damage on August 10, some of which overlapped the drought area. With these events come an increased risk for ear rots and associated mycotoxins. This article will address ear rots and mycotoxins of particular concern this year, in addition to scouting methods and monitoring considerations while grain is still in the field.

Sampling Downed Corn for Damage

September 9, 2020

The Derecho storm on August 10 left fields with varying degrees of downed corn. In the weeks following the storm, the condition of the corn plants has worsened and the quality of the corn grain appears to be deteriorating. This deterioration in quality is expected to increase with time. 

Water Quality Impacts of Cover Crop Following a Drought

September 3, 2020
Annual nitrate-N concentration in the corn year at the Gilmore City Drainage Research Facility

The dry conditions throughout large areas of Iowa during 2020 reminds us of Iowa’s last significant drought in 2012 and the subsequent impacts on nitrate-N levels in subsurface drainage the following spring. This article will address concerns for water quality in drought conditions and opportunities to reduce nutrient losses from fields this fall.

Cover Crop Options to Consider for Damaged Crops this Fall

August 27, 2020

Many fields have been ravaged by adverse weather this year in Iowa. On top of drought and hail we had a devastating derecho steam-roll a wide swath of Iowa starting in Sac County and progressing eastward along Highway 30. Along with the decision of how to handle this year’s crop, consideration for protecting the soil and preparing for next year’s crop should include cover crops.

Harvest and Storage of Weather-damaged Corn for Silage

August 18, 2020

Extreme weather events may lead to a decision to make corn silage rather than harvest corn for grain, or to harvest acres that will exceed current silage storage capacity. Before harvesting for silage, make sure you have a market for the silage or a sufficient number of livestock to feed it to. It may be difficult to harvest good quality corn silage if the crop has weather damage and the economic value of the silage will likely be lower than silage from non-damaged fields.

Silage Harvest of Drought-Stressed and Severely Lodged Corn

August 18, 2020
table 1

The decision to chop corn for silage should be made when there is no further potential to increase grain dry matter and whole plant moisture is in the proper range for the storage structure. The proper harvest moisture content is the same for drought stressed and normal corn. Recommended whole plant moisture contents are 65-70% in horizontal silos (trenches and bunkers), 60-70% for bags, 60-65% for upright stave silos, and 50-60% for upright oxygen limiting silos.

Wind Damaged Corn – Nutrient Content?

August 17, 2020
table 1

The August 10, 2020 high winds (derecho) caused lodged or flattened corn in many Iowa fields. The corn development ranged mainly from stages R3 (milk) to R5 (dent). Some fields may not be harvested, some chopped for silage, and some harvested for grain. Nutrients such as nitrogen (N), phosphorus (P), and potassium (K) remaining in the field may be different than with normal harvest due to partial plant removal, grain harvest, or grazing. Therefore, adjustments can be made for future fertilizer or manure applications.

Expectations for Lodged Corn

August 17, 2020

Derecho. Another of those words we wished we hadn’t heard in 2020 but are quite certain we won’t forget about the results from its occurrence. Millions of corn acres were damaged, and there are many questions about the lasting impact.

In cornfields, what did it leave behind? The damage varies considerably, but for this article, let’s break injury into three categories:

Using Cereal Rye Cover Crop and Narrow-Row Soybean to Manage Herbicide-Resistant Waterhemp

August 6, 2020
Waterhemp density in soybean with marginal (left) vs. aggressive weed control program plus harvest weed seed control (right) in previous year’s corn.

Waterhemp control is an increasing challenge for soybean producers due to the evolution of multiple herbicide-resistant populations. With dwindling herbicide resources, there is a need to integrate non-chemical strategies into current weed management programs in soybean. Cereal rye is the most common cover crop grown in the Midwest due to its winter hardiness and short life cycle. The high C:N ratio of cereal rye compared to legume or brassica cover crops results in a slow degradation of the residues; thereby, increasing the duration of weed suppression.

Scout Now for Palmer Amaranth

July 28, 2020
meaghan standing next to palmer plant

This is the time of year to begin scouting for Palmer amaranth (Amaranthus palmeri) in Iowa crop fields. While Palmer amaranth has been identified in more than half of Iowa’s counties, new identifications have waned since the widespread introductions in 2016. Palmer amaranth is still a species to watch out for in every Iowa crop field. Minnesota recently reported finding the weed in a county previously not known to have infestations – thus the weed is still on the move.

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