Integrated Crop Management News

Every spring, alfalfa growth and development differs due to variations in climatic, variety, stand age and other crop production factors. With the 2020 growing season being off to a cooler than normal start, alfalfa growth is also off to a slower start this spring. This is a good reminder that while calendar date is one method used to determine when to harvest first crop alfalfa, it 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.

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 rely on the accumulation of growing degree days (GDD) to predict activity. Alfalfa weevil egg hatching begins when 200-300 degree days have accumulated since January 1.

Bean leaf beetle adults (Photo 1) are susceptible to cold weather and most 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 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 soybean and other hosts. While adult activity can begin before soybean emergence, peak abundance often coincides with early-vegetative soybean.

Over the past two decades, scientists and beekeepers alike observed drastic declines in bee populations. On average, beekeepers lose significantly more honey bee colonies each year and fewer native bee species are spotted in the wild. This is especially apparent in the Midwest where research conducted at Iowa State University observes multiple factors that contribute to the decline in bees and other pollinators. According to an annual Bee Informed Partnership survey, Iowa beekeepers typically lose between 40-60% of their hives each year.