Integrated Crop Management News

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High Mortality Rates for Bean Leaf Beetle in Northern Iowa

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 from harsh temperatures under plant debris and loose soil. Each spring, adult beetles emerge from their 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.

Termination Timing of Cereal Rye Cover Crop for Improved Weed Control in Soybean

Current cooler weather conditions are posing challenges for growers with a cereal rye cover crop to get it terminated. However, for growers planning to plant soybeans into the rye cover crop, there may be a perk to letting the rye cover crop accumulate more biomass. That perk being the cover crop biomass can help with weed suppression. The ability of cereal rye to suppress weeds is directly related to the biomass accumulation at the time of termination.

Spring Forage Management Considerations

Pasture and forages stands have really started to green-up. Here are some fertilizer and weed management considerations and recommendations to help make the most out of pasture and forage stands this year.

Fertilizer considerations

Fertilization is just as important for forages as it is for row crops to maximize productivity. However, current fertilizer prices may have you seeing a lot of dollar signs.

Phosphorus, potassium, and lime considerations

To terminate or not to terminate?

Current cool temperatures increase the risk of failures in terminating cover crops. While cereal rye continues to grow during these conditions, activity of herbicides is reduced. Translocation of glyphosate to growing points is reduced under cool temperatures, slowing activity and increasing the potential for control failures. It is generally recommended to avoid applications when nighttime temperatures fall below 40 F, and we prefer temperatures at application to be at least in the mid-50s with clear skies.

Check FieldWatch® Before Pesticide Applications

Prepare for a safe pesticide application season by checking the FieldWatch® registry before making pesticide applications. The FieldWatch® registry provides easy-to-use, accurate, and secure online tools to enhance communications and awareness between crop producers, beekeepers, and pesticide applicators.FieldWatch® features a voluntary mapping tool through Google Maps™ that shows pesticide applicators the locations of registered sensitive crops and beehives so they can make informed decisions regarding pesticide applications.

Alfalfa Weevils Active throughout Southern Iowa

Adult alfalfa weevils become active and start laying eggs as soon as temperatures exceed 48°F. Like other insects, the development of alfalfa weevil depends on temperature, and we can use accumulation of growing degree days (GDD) to predict activity. Alfalfa weevil egg hatching begins when 200-300 GDD (base 48°F) have accumulated since January 1.

Seedcorn Maggots Get an Early Start

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

Preemergence Herbicides, Dry Soils and Rain

‘Preemergence herbicides need rain to be effective’

The potential for continued dry weather across the state raises concerns about the impact of dry soils on preemergence herbicides. Preemergence herbicides kill weeds by being absorbed into the seed as the seed imbibes water. To be effective, the herbicide must be located within the soil profile at the depth where weed seeds germinate (primarily the upper inch of soil). In addition, there must be sufficient water to keep the herbicide dissolved in soil water. Both factors can be adversely affected by limited rain early in the season.

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