Integrated Crop Management News

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Weeds in a Wet Year

May 22, 2019

The delays in planting get the headlines (for good reason), but another issue with prolonged wet periods is the inability to manage weeds and cover crops in a timely fashion. The following is a brief review of some of the problems that may be encountered.

Late-Spring Soil Nitrate Test (LSNT) Use in 2019

May 22, 2019

Nitrogen (N) fertilization for this year’s Iowa corn crop has been complicated by frequent and sometimes excessive rainfall from late last fall through this spring. Many farmers who normally apply N in the fall couldn’t, and spring preplant N application and corn planting has been challenging in many areas with the wet and extended cold soil conditions. Therefore, many farmers are uncertain about the N availability for corn, early post-emergence assessment of soil N supply, and the potential for supplemental sidedress N application.

Evaluating Soybean Stands

May 22, 2019
Feet of row representing 1/1,000 of an acre at different row widths

As of May 20, an estimated 27 percent of Iowa’s soybean crop is planted according to the USDA-NASS Iowa Crop Progress Report.  Early-planted soybeans have been exposed to stressful conditions following multiple rainfall events, cold temperatures, and wide temperature swings in the last several weeks.

Recycling Pesticide Containers

May 16, 2019

Handling and disposing of empty pesticide containers is a necessary part of pesticide applications and recycling containers is an environmentally friendly and responsible way of disposing of them. In 2018 763,078 pounds of pesticide containers 55 gallons and smaller were collected and recycled for the state of Iowa. Iowa ranked number one in the Midwest for containers recycled in 2018.

Recycling options vary depending on the container size:

Alfalfa Weevils Active in Northern Iowa

May 14, 2019
degree-day map for alfalfa weevils in 2019.

Keep alfalfa weevils in mind while scouting for stands and evaluating for winter injury. A recent ICM News article gave some great tips for assessing winter injury and providing additional resources. 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.

Seedcorn Maggots Flying in Iowa

May 14, 2019
Degree-day map for seedcorn maggot in 2019.

Seedcorn maggot is a seed and seedling pest of corn and soybean. Plant injury is especially prevalent during cool and wet springs. The larvae, or maggots, feed on germinating corn and soybean seeds or seedlings (Photo 1). They can feed on the embryo, delay development or kill the plant. Infestations tend to be field-wide instead of having a patchy distribution like for many other pests. To confirm seedcorn maggot injury, check field areas with stand loss and look for maggots, pupae and damaged seeds (e.g., hollowed out seeds or poorly developing seedlings).

Late Soybean Planting Options

May 13, 2019
soybean yield departure from trend line by 50% soybean planting date

This spring's weather conditions may be slowing down corn planting but soybean planting has not yet been impacted. As of May 5, soybean planting progress is estimated at 8% compared to 11% for the 5-year average (USDA-NASS, 2019). However, because of recent rains and corn planting delays there is concern that soybean planting will soon fall behind. In this article, we discuss the soybean yield potential and maturity selection considerations as planting progresses into late May and possibly June.

Scouting for Black Cutworm 2019

May 13, 2019
estimated cutting dates

Black cutworm (BCW) is a migratory pest that cuts and feeds on early vegetative-stage corn. Black cutworm moths arrive in Iowa and other northern states with spring storms each year. These moths lay eggs in and around crop fields, and emerging BCW larvae can cut seedling corn. This pest is sporadic, making it essential to scout fields to determine if management is needed.

Estimate Alfalfa First Crop Harvest with PEAQ

May 10, 2019
predictive equations for alfalfa quality table

Every spring, alfalfa growth and development is different due to variations in climatic, variety, stand age and other crop production factors. With the 2019 growing season being off to a cooler than normal start, this has slowed alfalfa growth this spring. This is a good reminder that while calendar date may be one method used to determine when to harvest first crop alfalfa, this method is not the best method to use. Instead, the PEAQ method (Predictive Equations for Alfalfa Quality) developed by the University of Wisconsin does a better job.

Another Harsh Winter for Bean Leaf Beetle

May 10, 2019
Bean leaf beetle.

Bean leaf beetle adults (Photo 1) are susceptible to cold weather and most will die when air temperatures fall 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 hosts, such as alfalfa, tick trefoil, and various clovers. As the season progresses, bean leaf beetles move to preferred hosts, like soybean. While initial adult activity can begin before soybean emergence, peak abundance often coincides with early-vegetative soybean.