The spread of multiple herbicide resistant weeds brought an end to the era of total postemergence programs in soybean. Unfortunately, a prolonged rainy period prevented applications of preemergence treatments on many planted soybean fields in certain areas of the state. By the time fields are fit for field operations soybeans likely will be emerging and limit herbicide options in those fields.
Integrated Crop Management News
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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.
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?
The Pesticide Safety Education Program (PSEP) at Iowa State University and the Iowa Department of Agriculture and Land Stewardship (IDALS), Pesticide Bureau announce a new EPA-approved PowerPoint and narrated video to train workers and handlers under the 2015 revised Worker Protection Standard (WPS).
This 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.
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.
Landscape 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.
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 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.
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.