Adult Corn Rootworm Suppression to Prevent Oviposition

A chemical-control strategy that might eliminate the need for a grower to apply a granular insecticide at planting or cultivation time is the application of a foliar spray by a commercial aerial applicator. Iowa began experimenting with the application of foliar broadcast sprays to control adult corn rootworms in 1974. In theory, if female beetle numbers can be sufficiently reduced during the egg-laying period, a damaging population of corn rootworm larvae should not develop the following season. The technology that stimulated interest in the concept was the development of a persistent formulation of carbaryl insecticide (Sevin® 4-0il). Experiments conducted during 1974-1976 demonstrated that the formulation had sufficient persistence to warrant full-scale field testing

New Solutions in Con Rootworm Control

At this meeting you have already heard that the northern com rootworm can be a pest of rotated com. The western com rootworm also has been reported in rotated com. In one of the workshops, Dr. Mike Gray, an invited speaker from the University of Illinois, will explain the adaptation of the western com rootworm to com grown in rotation. Recently the western com rootworm has been reported in rotated Iowa com as well. The Iowa Extension Crop Specialist from northeast Iowa, Brian Lang, was aware of a grower in Allamakee County that has had root lodging in his rotated com for several years. During this past season, Brian placed traps in one of the grower\u27s fields to capture beetles as they emerged from the soil. The presence of beetles in the traps would indicate that com rootworm eggs were in the soil and larvae had survived on the crop of first-year com. Over a three-week period Brian\u27s traps averaged a total of 14 western com rootworm and 1.5 northern com rootworm beetles. The presence of adult northern com rootworms could be explained by extended diapause as Marlin discussed. The adult western com rootworms could mean that they also are capable of extended diapause or that the western is laying eggs in Iowa soybeans as they are east of us. During the next crop season we will be attempting to determine the extent and the reason for western com rootworm survival in rotated Iowa com

Watch Soybean Aphid Numbers - NOW

Last week the conditions in Minnesota were very good for soybean aphid reproduction. With those conditions, the populations increased rapidly in many locations throughout Minnesota. We have been expecting 2008 soybean aphid populations to be lower as they were in 2004 and 2006, but the 2008 weather has not been exactly “typical.

Black Cutworm Treatment Options

As technology traits in corn seed increase seed prices and the price received per bushel increases, it is wise to consider black cutworm management in corn. Many areas of Iowa were cool and wet last spring, 2008. That weather often delayed planting and created flooded areas that had to be replanted. These conditions may have caused black cutworms to be more common than usual

Will 2009 be a Soybean Aphid Year

After high numbers of soybean aphids last year, Iowa agriculturalists are beginning to ask the question, “Will 2009 also be an aphid outbreak year?” Iowa State University entomologists working in soybeans have not seen enough aphid eggs on buckthorn to be alarmed. Remember, however, that aphid numbers will vary greatly from area to area and field to field. The variability in aphid numbers will not only depend on the overwintering success of aphids, but also reproduction on buckthorn in the spring, planting dates, the variety of soybeans planted, environmental conditions including temperature and rainfall, and the numbers of natural enemies

Management of bean leaf beetle to reduce defoliation

The last three issues of the ICM newsletter have contained articles on the bean leaf beetle in soybean. The April 29 article reported high winter survival of the beetles; the May 6 article outlined the early-season management of the beetle and bean pod mottle virus; and the May 20 article showed how to distinguish between twelvespotted lady beetle and bean leaf beetle. My article adds to the saga by discussing beetle management to reduce defoliation

Calculation of specific economic thresholds for the commercially available yellow sticky traps used for adult corn rootworm monitoring

During the mid 1980s, Iowa State University researchers described a sampling program that used yellow sticky traps for monitoring adult corn root worms. The Pherocon AM trap, then available commercially, served as the basis for a sampling program. This program was pro­ posed as a practical means for commercial corn growers to predict the need for soil insec­ ticides to protect a subsequent year\u27s corn crop from corn rootworm larval damage. Using this decision tool, farmers were expected to apply insecticides only when needed instead of preventively. Since then, a trap called the Multigard, from an additional supplier, has been used to monitor beetle populations. Both traps are yellow, rectangular cards coated with adhesive. The traps differ in color, however; the Pherocon is canary yellow and the Multigard is a fluorescent yellow

Should I Be Concerned About Corn Rootworms Now?

It is March already, the tillage equipment is being readied, and we are thinking eagerly about planting the 2008 crop of corn. Yet it seems a long time until we have to worry about corn rootworm larval feeding on the corn roots. However, there is something that you should be thinking about now, before you plant the corn

Evaluation for an integrated pest management program for northern corn rootworm extended diapause

Until about 1965, nearly all the northern corn rootworm (NCR) reproduced a single generation yearly. Because it could only survive on cultivated corn and its dispersal stage never coincided with the beginning of a cropping season, crop rotation controlled this pest in Iowa corn fields for over a century