Integrated Crop Management News

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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.

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?

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?

Black Cutworm Monitoring 2017

May 9, 2017
black cutworm feeding on corn leaves and seedling stalk

black cutworm feeding on corn leaves and seedling stalkThis 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

May 1, 2017

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.

Scouting for Pests in Iowa Cover Crops

April 24, 2017
true armyworm

true armywormLandscape diversification, including the use of cover crops, can provide habitat and forage for beneficial insects. This is especially true in the spring when there is a lack of food. Alternatively, cover crops can also support field crop pests, including moths, beetles, flies and slugs. The early spring vegetation, sometimes called a “green bridge,” provides resources until the row crops emerge.

Alfalfa Weevils Active Throughout Southern and Central Iowa

April 10, 2017
alfalfa weevil adult

Adult alfalfa weevils become active and start laying eggs as soon as temperatures exceed 48°F. Alfalfa weevil eggs develop based on temperature, or accumulating degree days, and hatching can start around 200-300 degree days. Start scouting alfalfa fields south of Interstate 80 at 200 degree days and fields north of Interstate 80 at 250 degree days. Based on accumulated temperatures since January, weevils could be active throughout southern and central Iowa (Figure. 1).

Bean Leaf Beetle Mortality Predictions

April 7, 2017
Predicted overwintering mortality of bean leaf beetle

Bean leaf beetle adults (Photo 1) are susceptible to cold weather and most will die when the air temperature falls below 14°F (-10°C). However, they have adapted to winter by protecting themselves under plant debris and loose soil. Each spring, adult beetles emerge from overwintering habitat and migrate to available host plants, such as alfalfa, tick trefoil, and various clovers. As the season progresses, bean leaf beetles move to more preferred hosts, like soybean.

Plan to Scout Alfalfa Stands for Winter Survival

March 13, 2017

A warm weather pattern in late February caused soil temperatures across most of Iowa to rise above 40 degrees Fahrenheit (F). This warm period was likely long enough for alfalfa and some forage grasses (most ryegrass varieties and less winter-hardy orchardgrass and tall fescue varieties) to break dormancy. When low temperatures resume, alfalfa plants can reharden to a degree, but only to the extent that it still has stored carbohydrates available.

Resistance Management Plan for Soybean Aphid

February 14, 2017

Soybean aphid remains the most important soybean insect pest in Iowa, and management over the last fifteen years has primarily relied on using foliar insecticides. The economic injury level was defined in 2007, and is approximately 675 aphids per plant or 5,560 cumulative aphid days. From that multi-state research, a conservative economic threshold was developed to protect yield: 250 aphids per plant with 80% of the plants infested through the seed set plant growth stage (R5.5).