The planting season may be wrapping up, but the crop protection season has just begun. And there are a myriad of legged and rooted pests that will be doing their job to reduce your yield for the year. Scout your fields, report to your consultants what you have found, and take action to protect your revenue from the new crop of corn and soybeans.
• Corn rootworm began hatching the first week of May, which Purdue entomologist Larry Bledsoe says is the earliest hatch in the past 35 years. Illinois entomologist Mike Gray says that is significant for this year, “Unlike in previous years, corn rootworm larvae this spring will be feeding on small-rooted corn plants in drier soil conditions. I anticipate good larval establishment this season, and where densities are high, significant pressure will be exerted on the root systems of corn plants throughout May and into mid-June. With a larval hatch some 3 to 4 weeks early, anticipate the early arrival of adults, possibly by mid-June.”
• Bean leaf beetles are crawling toward your soybeans. Because of the mild winter, more of the adults have survived and are awaiting newly emerging soybeans. That implies there will be more second generation beetles, both of which will carry a viral disease that reduces the value of soybeans by discoloration. Iowa State University entomologist Erin Hodgson says the number of beetles might be reduced by the high adoption rate of insecticidal seed treatments.
• Soybean aphid researchers have long said predator insects such as ladybugs may be a better control method for aphids than insecticides. Michigan State University researchers are now recommending creating communal habitats for ladybugs and other insect predators around fields so they will be ready to pounce if the aphids arrive. They have said such a habitat within 1.5 miles is important, and have suggested that neighbors cooperate on a jointly-owned predator habitat.
• Corn seedling diseases are being reported heaviest in corn planted April 23-27, prior to a cold, wet spell. Iowa State University plant pathologists report pythium fungi are to blame for destruction of some seedlings that did not have good root growth prior to the deterioration of the mesocotyl that helped get moisture to the young seedling. Ohio State University researchers report that some seed treatments have worked to prevent problems, but not on all species of the fungus.
• Are you rotating corn herbicides? Avoid crop injury with the careful application of post-emergent herbicides, says Purdue weed specialist Travis Legleiter. Avoid application of a contact herbicide prior to rain to prevent it washing into the whorl. Avoid the use of growth regulators after several nights of temperatures of 45º or cooler. When tank-mixing, follow the most restrictive label to determine the right crop growth stage restriction.