Personnel from Ohio State University Extension continued to sample for western corn rootworm adults (WCR) in soybean fields for the ninth year. Data from the 2005 rootworm trapping program have been assembled. This is an overview of the results from that survey. Sampling was done using Pherocon? AM yellow sticky traps placed in 94 fields covering 26 counties ( see map). Six traps were placed in the soybeans on metal posts at canopy height and located at least 100 feet from the field edge and evenly spaced in the field. The traps were initially placed in fields in late July and removed in late August or early September. Traps were serviced once a week throughout the sampling period with a new, clean trap. After each trapping week, the numbers of beetles collected were summed and divided by the number of traps (6) and the number of days the traps were in the field resulting in the average number of beetles collected per trap per day.

A summary of the weekly catches of WCR adults per trap per day from the 2005 growing season is presented in Table 1. Research indicates that catches in soybean of 5 or more beetles/trap/day during any trapping week indicates a potential problem with rootworm in the field the following year.

The trapping data from 2005 had the following results from the 94 fields:

Only a single field with an average > 5 beetles/trap/day Five fields with an average between 4 and < 5 beetles/trap/day Most fields were <3 beetles/trap/day

The field that had > 5 beetles/trap/day was in Williams County. Those fields between 4 and 5 beetles/trap/day were in Champaign (2), Shelby, Van Wert, and Williams Counties. We should mention that many fields, especially those in NW Ohio, had also been sprayed for soybean aphid. It is not clear exactly how that might have effected the collection of FYWCR; however, we believe that if there were high numbers of the WCR, they would have been collected in higher numbers on the yellow sticky traps at least one time during the sampling survey. Additionally, we did not hear of many problems with FYWCR in first year corn this past summer.

So What Does This Mean?

Based on the potential treatment level of 5 beetles/trap/day during any trapping week, if the single field with over 5 beetles/trap/day is planted to corn in 2006, a treatment of either a soil insecticide, Poncho 1250 or Cruiser CRW seed treatments (the highest rate of each), or a transgenic rootworm corn (YieldGard Rootworm or Herculex RW, or perhaps YieldGard Plus or Herculex Xtra) should be considered for control of rootworm. As we have stated previously, these data do not mean that other fields in a county that were not sampled do not need treatment. But we feel that the data do give good information about the fields that were sampled and about the overall abundance of the beetles this year. Rootworm populations continue to be relatively low. We do NOT recommend widespread treatment for rootworms unless you had scouted your field and know you have a population in the field. However, there might be those very few soybean fields that do have populations sufficient to warrant treatment next spring. Because of this continued concern with this insect, we urge growers to develop a sampling plan next year in their soybean fields, and to sample roots for feeding injury in their first year corn for the presence of FYWCR.

Counties and personnel involved with the first year corn rootworm trapping in 2005.

County	Agent	County	Agent
Allen	C. Young	Miami	H. Watters
Auglaize	J. Smith	Morrow	S. Ruhl
Champaign	H. Watters	Paulding	J. Lopshire
Crawford	S. Prochaska	Putnam	G. Arnold
Darke	S. Foster	Sandusky	M. Koenig
Defiance	B. Clevenger	Seneca	E. Lentz
Fulton	G. Lebarge	Shelby	R. Bender
Henry	D. Sonnenberg	Van Wert	A. Kleinschmidt
Hancock	G. Wilson	Williams	F. Chirra
Mercer	T. Mangen	Wood	A. Sundermeier

Funds for traps were provided by Monsanto, Pioneer Hi-Bred International and a grant from the OSU IPM Program to the OSU Extension Agronomic Crops Team.

| Back |