Integrated Crop Management News

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Corn Rootworm Egg Hatch Peaking Around Iowa

June 12, 2017
Predicted corn rootworm egg hatch in 2017

Corn rootworm egg hatch in Iowa typically occurs from late May to the middle of June, with an average peak hatching date of June 6 in central Iowa. In 2017, the average hatching date will be about the same time as the 2014-2016 growing seasons. Development is driven by soil temperature and measured by growing degree days. Research suggests about 50 percent of egg hatch occurs between 684-767 accumulated degree days (base 52°F, soil). Most areas in Iowa have reached peak corn rootworm egg hatch or will within a few days (Figure 1).

Stalk Borers Moving in Southern Iowa

May 26, 2017
Economic threshold table for stalk borer

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

May 26, 2017
precipitation map April to May

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).

Iowa Sensitive Crops Directory Converted to FieldWatch, Inc.

May 25, 2017

The Iowa Department of Agriculture and Land Stewardship (IDALS), ISU Extension and Outreach Pesticide Safety Education Program, and the Iowa Agribusiness Association of Iowa want to remind pesticide applicators in Iowa that IDALS’ Sensitive Crop Directory has now partnered with the nonprofit company FieldWatch, Inc. to offer producers two online registries for sensitive crops and apiaries with a third online registry for applicators to view and download producer entries. These registries replace the former Iowa Sensitive Crop Directory.

Evaluating Herbicide Injury on Soybean

May 25, 2017

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

May 24, 2017

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

May 23, 2017

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.

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

May 15, 2017
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?