Grasshoppers and insecticides

Each year, I hear the statement that grasshoppers must be sprayed when they are small because adult grasshoppers are notoriously hard to kill. I was not certain that this statement was true, so last year I sprayed adult differential grasshoppers in a laboratory experiment. Ten adult grasshoppers were singly caged in paper cups and covered with nylon mesh for each treatment. Cups containing the grasshoppers were then sprayed in a mechanical spray chamber with an insecticide at a rate of 19.6 gallons of water per acre and 25 psi by using an 80005-E nozzle

Producers and Applicators Legally Responsible to Heed Preharvest Intervals for Treated Soybean

Based on reports from my Extension agronomist colleagues, hundreds of thousands of soybean acres were sprayed with insecticides during July and August for control of soybean aphids and bean leaf beetles. All insecticides listed in Table 1 have at least a 21-day preharvest interval, and several have moderate intervals of 30 days or very long preharvest intervals of 60 days. The preharvest interval is the minimum number of days a farmer must wait before harvesting a treated crop

BugCast: A podcast about insects

Podcast--you may have heard the word, but you don\u27t know what it means. I can assure you that if you have kids in high school or college, they will know. It is relatively new technology that often, but not always, uses the iPod to capture and display either audio or video. According to Wikipedia, the free online encyclopedia, podcasting is a method of distributing multimedia files, such as audio programs or music videos, over the Internet for playback on mobile devices and personal computers

Western bean cutworm flight near the end

The flight of the western bean cutworm is coming to an early close this year. Blacklight trap captures from both Boone and Woodbury counties indicate that the populations peaked on July 5 and July 9, respectively (see figures). The historical data from Woodbury County indicates that the flight started six days earlier, and peaked six days earlier, than it had any previous year in western Iowa. It appears that the flight will end considerably earlier; maybe by as much as 10 to 14 days

Evaluate insecticide seed-treated cornfields

I have had reports of white grubs causing significant stand loss in a handful of fields, while reports of black cutworm and wireworm damage have been infrequently reported this spring. Now would be a good time to evaluate the performance of cornfields with insecticide seed treatments. The systemic seed treatments (Cruiser, Gaucho, and Poncho) were widely promoted last winter as effective treatments for control of white grubs, wireworms and cutworms

Lady beetles or bean leaf beetles

Misidentification of insects is not uncommon. The colors, shapes, and sizes of the legions of insects that inhabit Iowa often exceed our own imaginations. However, for those of us involved in agriculture, there are several dozen insects that we should recognize. Two are the twelvespotted lady beetle (also called the spotted lady beetle) and the bean leaf beetle. The former is a beneficial, and the latter a serious pest. I would not have given the confusion over the identification of these two insects serious thought if not for a surprise encounter this week. A clear plastic bag, containing dozens of twelvespotted lady beetles was delivered to campus along with the comment, This sure looks like a bad year for bean leaf beetles

Soil insecticides and replanting restrictions

Cool soil conditions have delayed emergence of some early planted fields. Information from southern Iowa indicates that 3 weeks after planting some corn has yet to emerge. Poor plant stands may result from poor germination or be caused by soil insects such as white grubs or wireworms. For farmers that need to replant and that previously applied a soil insecticide, questions may be raised about what product can be legally used during the replanting operation

The Bt corn refuge: Is it really necessary?

Corn growers are increasingly adopting the corn biotech traits in YieldGard®, Herculex®, and Agrisure® for yield protection against corn rootworms and/or European corn borers in what we call Bt corn hybrids. All of these traits require that corn growers follow Insect Resistance Management (IRM) requirements to effectively manage this technology. Surprisingly, I heard numerous corn growers during my recent winter meeting circuit around the state scoff at the IRM requirements. I\u27m sure many of them were thinking, is a Bt corn refuge really necessary

Cowpea aphid: a new pest in Iowa alfalfa?

Iowa producers may have a new pest to contend with in alfalfa. On July 29, Joel DeJong, ISU field specialist-crops, and I visited an alfalfa field near LeMars that had large populations of “black” aphids as reported by Peter Westra and Todd Russ (LeMars Agri-Center, LeMars, Woodbury County). The field was suffering from drought stress and small populations of aphids were fairly easy to find. Hal Tucker (Tucker Consulting, Storm Lake) also has reported finding alfalfa fields with black aphids covering entire plants in northwestern Iowa

Leafminer injury common in soybean

Several crop scouts have inquired about soybean leaves with brown pockets or blisters often found along the edge of the leaflet. These blisters are the chambers created by soybean leafminer larvae. Only one larva occurs in each chamber, but I have seen leaflets with as many as three chambers and larvae. I have never seen any economic damage caused by the larvae but the adults do transmit bean pod mottle virus. The adult leafminer was featured in the June 17, 2002, Integrated Crop Management newsletter, page 102