Integrated Crop Management News

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Corn Rootworm Peak Egg Hatch is Occurring

June 20, 2024
corn rootworm egg hatch 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 larvae in cornfields.

Are Nematodes Causing Stunted, Yellow Corn?

June 19, 2024
Nematode A.

Plant-parasitic nematodes that feed on corn are relatively common in Iowa. But their mere presence in soils does not mean that damage and yield loss are occurring. Symptoms of damage include stunting and yellowing of leaves. This article explains how to sample corn fields to determine if nematodes are causing damage and are likely to reduce corn yields.

Japanese Beetle Adults Emerging Now

June 13, 2024
Growing degree days map.

Japanese beetle development seems to be a bit ahead of schedule this year, which is not surprising with the warm temperatures this 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).

Start Looking for SCN Females on Soybean Roots Four Weeks After Planting

June 11, 2024

The moment a soybean field is planted, the clock starts ticking on when the first SCN females of the year will become apparent on roots. These females normally can be seen about four weeks after planting. For Iowa this season, the first SCN females will begin appearing over many weeks in June and possibly early July for very late planted soybeans. This article reviews tips on how to look for SCN females on roots and what to do when they are found.

2024 Cover Crop Options in Prevented Planting Fields

June 7, 2024
Field culvert with flooding.

Continued above average rainfall from April through May has led to flooded fields and conditions that are too wet to plant or do field work in parts of Iowa. Early June planting decisions surrounding your delayed and prevented planting provision should involve a conversation with your crop insurance provider. The Ag Decision Maker File A1-57 talks about the insurance provision implications related to late planting, prevent planting, and replanting decisions in Iowa.

Forage Options with Prevented Planting Fields

June 7, 2024
Multiple sorghum species.

Many fields are flooded or too wet to continue planting in many parts of Iowa. Delayed and prevented planting crop insurance dates are fast approaching with an unfavorable weather forecast. Decisions surrounding delayed and prevented planting provision need to involve a conversation with your crop insurance provider. There is a nice article available on the Ag Decision Maker website that talks about the insurance provision implications.

Begin Scouting for Stalk Borers

May 31, 2024
corn leaves shreded by stalk borer.

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.

Asian Copperleaf Makes a Return

May 24, 2024
Asian Copperleaf.

As of this spring, we’ve identified Asian copperleaf (Acalypha australis) in crop fields in six counties, and it's likely in more. As we find more populations, it is easier to monitor their development through the growing season. Field agronomists have been monitoring two of the infestations this spring and have observed many emerged seedlings in Boone and Franklin counties. As farmers scout fields and prepare for postemergence herbicide applications, it is important to keep an eye out for this new Iowa weed.

Blast from the Past: European Corn Borer is Back on the Radar

May 19, 2024
European corn borer moth

European corn borer (ECB) is a pest that most farmers haven’t had to think about since the late 1990s. ECB was the main target of the first Bt corn hybrids introduced to the market in 1996. Since then, Bt hybrids have effectively managed ECB populations and even provided economic benefits to farmers that don’t use Bt through areawide suppression. Before this, ECB was estimated to cost U.S. farmers over a billion dollars annually in yield losses and control costs, earning it the title of “the billion dollar bug.”

Start Scouting for Black Cutworm in Emerged Corn

May 8, 2024
Black cutworm cutting map.

Black cutworm (BCW) is a migratory pest that arrives in Iowa with spring storms each year. Black cutworm moths lay eggs in and near crop fields, and larvae can feed on leaves or cut corn seedlings. Larvae must attain a certain size (fourth instar) to be large enough to cut corn plants, and cutting can occur until plants reach the V5 stage (five leaf collars present). Black cutworm is unpredictable, making it essential to scout to determine whether BCW larvae are present in a field and if management is required.

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