Integrated Crop Management News

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Planning a Late Summer Perennial Forage Seeding?

July 23, 2020

Late summer can provide a window of opportunity to seed perennial forage legumes and grasses, whether you want to establish a new forage crop or need to fill in bare and thin spots in an existing forage stand. To help improve the chances for a successful late summer seeding of forages, consider the following.

Field preparation prior to seeding

Scouting reminders for spider mites

July 20, 2020
Twospotted spider mite.

As parts of Iowa enter severe drought on July 14 (D2, US Drought Monitor), I encourage you to scout for twospotted spider mites in crops. Twospotted spider mites can increase whenever temperatures are greater than 85°F, humidity is less than 90 percent, and moisture levels are low. These are ideal conditions for the twospotted spider mite and populations are capable of increasing very rapidly.


Potato Leafhoppers Abundant in Soybean and Alfalfa

July 10, 2020
Potato leafhopper adult (top) and nymph (bottom).

This year we have received many inquiries about potato leafhopper (Photo 1) in soybean and alfalfa. Although they are present in Iowa every year, populations are higher than in 2018 and 2019. Usually, potato leafhoppers are only considered a pest of alfalfa in Iowa, but they do feed on soybean, too. Potato leafhoppers prefer smooth leaves and are usually repelled by varieties with pubescence (hairs).

Measuring Conservation and Nutrient Reduction in Iowa Agriculture

July 9, 2020
Agricultural land use over time in Iowa.

An ongoing public concern is the loss of nutrients from agricultural land in the corn belt. In Iowa, nitrogen and phosphorus losses from farm fields are driven by a variety of factors. Since the mid-twentieth century, statewide corn and soybean acres have increased as extended rotations, hay, and pasture declined. Compared to perennial crops and small grain rotations, corn-soybean and continuous corn rotations are leaky systems.

Soybean Gall Midge Larvae Active in Iowa

July 2, 2020
Soybean gall midge distribution from 2018 and 2019 map

Soybean gall midge was confirmed as an economic pest of soybean in 2018. Worldwide, it is only known to occur in five states in the Midwestern US (Figure 1). Research began in 2019 to monitor the emergence of adults and incidence of larval feeding, as well as management options for the pest. This year, soybean gall midge adults were first collected on June 12 and larvae were detected in soybean on June 23.

Planted Non-Bt Corn? Plan to Scout for European Corn Borer

June 12, 2020

Farmers have enjoyed the benefits of Bt corn since its introduction in 1996, particularly “in the bag” transgenic protection from insect pests and the yield loss they inflict. European corn borer (ECB), Ostrinia nubilalis, was particularly challenging and the target of the first Bt hybrids. The adoption of Bt corn in the U.S. prompted a widespread suppression of ECB. Even so, ECB still shows up in conventional cornfields in Iowa and can be a devastating pest.

Watch for Japanese Beetle Emergence

June 11, 2020
growing degree map of iowa

Several Iowa State University Extension and Outreach Field Agronomists have reported fields with high numbers of grubs this spring. There are a number of grub species in Iowa, including Japanese beetle. With warm temperatures accelerating insect development, expect adult Japanese beetles to begin emergence in southern Iowa counties this weekend (Figure 1). The emergence is about 7-10 days ahead of the last few years. Literature shows Japanese beetle adults need about 1,030 growing degree days (base 50°F) to complete development and will continue emergence until around 2,150 degree days.

Corn Rootworm Egg Hatch Getting a Late Start in Iowa

June 9, 2020

Corn rootworm egg hatch in Iowa occurs from late May to the middle of June, with an average peak hatching date of June 6 in central Iowa. In 2020, the expected hatching date will be behind the average due to cool spring temperatures. Development is driven by soil temperature and measured by growing degree days. Research suggests about 50% of egg hatch occurs between 684-767 accumulated degree days (base 52°F, soil). Most areas in Iowa will reach peak corn rootworm egg hatch in 5-7 days (Figure 1).

Aphids Observed in Alfalfa Fields

June 5, 2020

Alfalfa weevils aren’t the only insect pest being found in alfalfa fields this spring. Reports of aphids, particularly cowpea aphids and pea aphids, have been made around the state. This article will discuss identifying the common aphid species found in Iowa as well as scouting and management recommendations for aphids in alfalfa.