Corn rootworm isn?t called the billion-dollar pest for no reason and as we are moving right along this growing season, now is the time where corn rootworm is starting to make its appearance and cause the most damage in fields, so farmers need to be on the lookout.
AgriGold agronomist based in northern Illinois, Kevin Gale, says corn rootworm should be at the top of your mind this growing season.
?No doubt, there was high pressure in 2021, and with it lots of egg laying and low mortality rates this spring set the stage for high pressure again here in 2022. Soils were drier as root warm eggs hatch this spring, especially in the northern part of Illinois-Central Iowa corridor. We didn’t have a very cold winter, so we suspect mortality rates are low for larvae. High pressure is likely to continue until we get those saturating rains right at rootworm hatch. Continuous corn acres are likely to have the highest pressure. beetles are attracted to pollen, So fields that were planted late and those with lots of volunteer corn or weeds in Beanfields are also prime candidates for high rootworm pressure.?
Gale says farmers need to consistently be scouting for corn rootworm throughout the next six weeks. He says each node pruned can reduce your yield up to 15 percent, so farmers need to stay on top of the pest.
?I would expect beetle emergence to begin right away, it’s going to be right on time, typically now until the end of July, depending on where you’re at in the Corn Belt. So, now’s a great time to be scouting fields. Root digs can show what level of damage we see in our fields and determine if our management or trait choices are offering good control. With smaller root systems on some of the later planted crop this year, damage may be more visible, especially in areas hit by the July 5 storm that rolled through the Dakotas, Iowa and Illinois. As beetle start to emerge, we can gauge pressure by placing yellow sticky traps in fields and by counting beetles. If you average two beetles per day over a week timeframe in a corn-on-corn environment, we need to make sure we’re controlling rootworm with different management practices next year. In a corn-bean rotation, that threshold is an average of one and a half beetles per day over a weekly timeframe.?
Gale mentions where the areas who are at high-risk for corn rootworm pressure are this season.
?Yeah, significant pressure areas are typically that Northern Tier or northwest Illinois, the areas that I cover, where we’ve had higher incidences of corn-on-corn acres and farmers that tend to use some of the same traits year after year. There’s also a lot of pressure in the western Corn Belt moving from Nebraska into Iowa, Wisconsin, and Minnesota. As we transition further east and south to areas with mainly crop rotation, we encounter less pressure. Growers in those areas may not be using traits that control corn rootworm as a result, so scouting is still going to be needed in those areas to determine if we can get by with that in the future.?
Gale says if a farmer happens to have heavy corn rootworm pressure that rescue treatment options are limited. Gale reassures that there are quite a few steps that farmers can take to control rootworm as they move forward.
?I Think the first obvious management tactic is use crop rotation if possible. You break up the corn rootworm cycle and you benefit from a higher soybean yield to following corn-on-corn. But if you’re going to grow corn-on-corn, number one, utilize a good traited hybrid like SmartStax, but AgriGold is excited to introduce SmatStax PRO products for 2023 planting as well, which offers a new mode of action with RNAi technology. If growing continuous corn, consider insecticide applications to help reduce pest pressure for next season. Typically, it’s going to take more than one application to get that entire crop of beetles under control, especially when beetles tend to emerge over several weeks. Timing is very important. You want to get those knocked down prior to egg laying. You also want to make sure we’re controlling volunteer corn in soybeans. This can allow corn rootworm to survive and lay eggs for next year’s crop. And lastly, reach out to your local agronomist. We have a lot of experience working through corn rootworm issues and can offer sound management advice going forward.?
To learn more and find an agronomist near you, visit AgriGold.com.
