Integrated Crop Management News

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Stalk Borers Moving in Southern Iowa

Tracking degree days is a useful tool to estimate when common stalk borer larvae begin moving into cornfields from their overwintering hosts. Foliar insecticide applications, if needed, are only effective when larvae are migrating and exposed. Start scouting corn for larvae when 1,300-1,400 degree days (base 41°F) have accumulated. Southern Iowa counties reached this important benchmark over the holiday weekend (Figure 1), and therefore scouting for migrating larvae should begin now to make timely treatment decisions.

Potential Nitrogen Loss in Spring 2017

Lately it seems to be an annual question with no exception this spring – has there been nitrogen (N) loss from my applied N? That question should also include what has been the N loss from the soil N supply or residual nitrate-N. There is usually tile drainage every spring and sometimes but not usually in the late fall (remember a couple of years ago). Also, losses if soils become saturated (free water filling the soil pores, standing water, anaerobic conditions) and soils are warm then denitrification happens (biological conversion of nitrate to N gas).

A New Late-Spring Soil Nitrate Test Publication Now Available

A new ISU Extension and Outreach publication, Use of the Late-Spring Soil Nitrate Test in Iowa Corn Production (CROP 3140), has replaced the previous publication (PM 1714). The publication is available from the ISU Extension Store.

Evaluating Herbicide Injury on Soybean

The potential for herbicide injury with preemergence herbicides is greater with soybean than corn. The risk increases with environmental conditions that reduce crop vigor and growth rate, and also with heavy rain that moves the herbicide to the depth of the germinating seed or emerging seedling. Much of the state has experienced these conditions, thus it is likely symptoms will be found in many fields as people return to the field with the improved weather.

Preemergence Herbicide Options for Planted Soybean Fields

The spread of multiple herbicide resistant weeds brought an end to the era of total postemergence programs in soybean. Unfortunately, a prolonged rainy period prevented applications of preemergence treatments on many planted soybean fields in certain areas of the state. By the time fields are fit for field operations soybeans likely will be emerging and limit herbicide options in those fields.

The Economics of Soil Health

The term “economics of soil health” has been used frequently in an attempt to quantify and validate the value of improving soil health. The traditional thinking about assigning dollar values to soil health metrics, which are many, can be very challenging and it is easier said than done.

One of the challenges in putting a dollar value on soil health is that the improvement in health is a long-term process. Expecting an immediate economic return can defeat the purpose of the long-term sustainability of soil health and its cumulative effects on soil productivity.

A Pest of the Past: Have You Seen Hop Vine Borer?

A common caterpillar we include in our ISU field guides is hop vine borer (Figure 1), but I can’t even remember the last time I saw one. I’m wondering if it’s an early-season pest of the past? Archived ICM News articles tell me it was most commonly observed in northeastern Iowa and states to the east. It was considered an occasional pest that caused stand loss in corn, particularly in fields with grassy weeds. Have you seen it lately?

Worker Protection Standard Training Video for Workers and Handlers Now Available

The Pesticide Safety Education Program (PSEP) at Iowa State University and the Iowa Department of Agriculture and Land Stewardship (IDALS), Pesticide Bureau announce a new EPA-approved PowerPoint and narrated video to train workers and handlers under the 2015 revised Worker Protection Standard (WPS).

Black Cutworm Monitoring 2017

black cutworm feeding on corn leaves and seedling stalk This is the time of year when calls about black cutworm (BCW) scouting dates start to roll in, especially when Corn Belt states to the east have reported high moth numbers in traps. Despite what is being observed in states to the east (Illinois, Wisconsin and Indiana), there have been relatively few captures in Iowa.

Update on Palmer Amaranth in Conservation Plantings

The 2016 growing season will be remembered by many for the widespread detections of Palmer amaranth across Iowa. While native seed mixes contaminated with Palmer amaranth seed used in Conservation Reserve Program (CRP) fields were the largest source of introduction, it is important to recognize that the weed was also found in at least 7 counties in areas other than CRP fields. Palmer amaranth seed can be transported by machinery, in feed or bedding and by wildlife, thus all fields in Iowa are at risk of being invaded by Palmer amaranth.

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