Integrated Crop Management News

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Keep an Eye out for Soybean Defoliators

July 12, 2023
Graphic explaining soybean defoliation.

When it comes to soybean, one of the most common types of injury is defoliation from insects. This damage can be easily detected in the canopy by observing holes in the leaves or along leaf margins as insects with chewing mouthparts consume leaf tissue. The insects most responsible for defoliation are bean leaf beetles, Japanese beetles, and grasshoppers. There are numerous caterpillars that also cause soybean defoliation, including green cloverworm, soybean looper and alfalfa caterpillar.

It's Time to Check Whether Corn Rootworm Management Worked

June 26, 2023
Accumulated soil degree days map.

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. Development is driven by soil temperature and measured by growing degree days (GDDs). Research suggests about 50% of egg hatch occurs between 684-767 accumulated GDDs (since January 1; base 52°F, soil). Most areas within Iowa have reached peak egg hatch for corn rootworm (Figure 1), and we have heard several reports of folks finding larvae by digging roots in cornfields.

Japanese Beetle Adults Now Emerging

June 16, 2023
Figure 1. Growing degree days accumulated (base 50°F) in Iowa (January 1 to June 16, 2023). Adults begin emerging after 1,030 degree days. Map courtesy of the Iowa Environmental Mesonet, Iowa State University Department of Agronomy.

Japanese beetle development seems to be a bit ahead of schedule this year, much like other pests we track each spring. Japanese beetle adults begin emergence when approximately 1,030 growing degree days (GDD; base 50°F) have accumulated since January 1 and will continue emerging until 2,150 GDD have accumulated. Japanese beetle adults likely began emerging in the southern portion of the state last week, and emergence will likely occur within the next two weeks in northern Iowa (Figure 1).

Wondering if plant-parasitic nematodes are the cause of stunted, yellow corn?

June 16, 2023
Discolored and stunted corn roots heavily infected with the root-lesion nematode, Pratylenchus spp.

Plant-parasitic nematodes that feed on corn are relatively common in Iowa, but their presence in fields does not mean that damage and yield loss are occurring. The number of nematodes necessary to damage corn varies greatly among different nematode species, and the potential for yield loss can only be assessed by determining the types and numbers of nematodes present in a field. This article explains how to sample corn fields to determine if nematodes are causing damage and likely to reduce corn yields. Management options for nematodes on corn also are listed in the article.

Plant Tissue Testing may be Useful this Season but be Aware of Potential Drought effects on the Results

June 12, 2023

Variable rainfall and soil temperatures across Iowa since April have resulted in variable planting dates and early crop growth. As of today, June 12, upper soil moisture ranges from deficient to about normal. Some producers and consultants are wondering if the dry conditions are affecting the normal crop uptake of soil nutrients and plant tissue-test results. Tissue testing is an in-season diagnostic tool that can be useful to assess plant nutrient sufficiency but is affected by deficient or excessive soil moisture.

Dig into Scouting for SCN

June 12, 2023
Adult SCN females (some indicated with yellow arrows) on roots of a soybean variety with PI 88788 SCN resistance. Seven nitrogen-fixing nodules also can be seen in the image on the larger tap root at the top.

Most soybean producers in Iowa have heard of the soybean cyst nematode (SCN) and are aware it is considered the most yield-reducing soybean pathogen in Iowa. Adult females of SCN can be seen on infected soybean roots with the unaided eye and they now are present on soybean roots. Read more in this article about digging roots to check for SCN.

Soybean Gall Midge Adults Now Emerging

June 8, 2023
Soybean gall midge adults.

Two male adult soybean gall midges were found in emergence cages at the Northwest Research and Demonstration Farm near Sutherland on June 6. This is about one week earlier than previous first captures in Iowa since we started monitoring emergence in 2019. The first Midwest report of soybean gall midge emergence in 2023 was May 31 near Mead, Nebraska. You can keep up with soybean gall midge emergence at

Stalk Borers are Migrating to Corn

June 6, 2023
Degree days accumulated for stalk borer in Iowa.

Stalk borer is an occasional pest of corn, but it can be persistent in some fields, especially those fields near perennial grasses that serve as overwintering sites (fence rows, terraces, and waterways are typical sources). Tracking degree days is a useful way to estimate when common stalk borer larvae begin moving into cornfields from their overwintering hosts. Foliar insecticide applications are only effective when larvae are migrating and exposed to the insecticide. Start scouting corn for larvae when 1,300-1,400 degree days (base 41°F) have accumulated.

Return Program Available for Certain Chlorpyrifos Products

May 11, 2023

In late April, the Environmental Protection Agency (EPA) authorized product registrants, Corteva Agriscience and Adama US, to proceed with accepting return shipments of certain cancelled products containing the active ingredient, chlorpyrifos.