(excerpts from publication "Managing Corn Rootworms - 1996")
C. Richard Edwards, Larry W. Bledsoe, and John L. Obermeyer, Extension
Entomologists
(excerpts from publication "Managing Corn Rootworms - 1996")
C. Richard Edwards, Larry W. Bledsoe, and John L. Obermeyer, Extension
Entomologists
Agriculturists in Indiana and Illinois have observed a steady and substantial increase in first-year corn fields (corn following soybeans) showing economic damage due to Western Corn Rootworm (WCR) larval feeding. Several years ago we received a few reports of rootworm larval feeding damage in first-year corn fields following soybeans in northwestern Indiana. Since WCR eggs are laid in late summer prior to hatch the next spring, the adults had to have moved into the soybeans to lay their eggs. Each year since then, we have seen a similar situation develop, but only in a slightly greater number of fields. The trend continued, and by 1995, hundreds of fields were reported as having the problem in northwestern Indiana, as well as few other areas of the state.
The following are given as possible explanations by Purdue entomologists:
Beetle adaptation to the
corn/soybean rotational system
Greater rootworm population
WCR in problem areas are
genetically different
Earlier corn planting/later
rootworm hatch cause WCR movement into soybeans
Corn residue in soybean fields
attracting the beetles
Drilled soybean production may
enhance WCR survival due to leaf canopy
In most fields, growers who rotate corn and soybeans annually will seldom need to use a rootworm soil insecticide. Also, corn grown in sand or muck soils is less likely to have a rootworm problem. The potential for most rootworm larval and adult problems can be determined by timely scouting and sampling.
A. Potential for a problem is minimal or nonexistent in first-year corn IF:
No WCR beetles were observed in the
soybean field the previous year.
B. Potential for economic rootworm problem exists in first-year corn IF:
In soybeans, WCR are numerous
during late July and/or August and the field will be planted to corn.
A field is being planted to corn
the first year following a soybean crop that had a high population of volunteer
corn or grassy weeds and rootworm beetles were present.
There are several references available from your local Extension office or Purdue University.
The information for this issue sheet was taken from this publication. The
publication provides detailed information about beetle and larval sampling,
criteria for applying corn rootworm control, performance of soil insecticides,
insecticide/herbicide/plant interactions, use of soil insecticides at reduced
rates, and more.
CONTACT: Your local Extension office
A comprehensive guide (550 pages) to the pests common to field crops in
Indiana. Includes color photos of the western corn rootworm (WCR) beetles and
larvae.
COST: $40.00
CONTACT: Entomology Extension Office, 1158 ARB,
Purdue University, West Lafayette, IN
49607-1158. Telephone (317) 494-8761.
Updated and printed annually, this pocket-sized guide provides brief
information about corn and soybean management, including descriptions of the WCR
larvae and adults, damage from the WCR, and how to sample to determine economic
thresholds.
COST: $3.00
CONTACT: Ag Communication Service, Media
Distribution Center, 301 S. Second, Lafayette, IN 47905-1092. Telephone
(317) 494-6794.
Published weekly from April through mid-September, and monthly February,
March, October, and November. Provides timely information of critical issues
during the growing season. For example, if the WCR is observed in several
fields, the next issue of the P&C Newsletter will address information
available about the extent of damage and control measures needed, if any.
COST: $30.00 plus sales tax in Indiana (5%)
CONTACT: Entomology Extension Office (see above address)
Edited by Karen Sowers, Gene Matzat, and Sarah Brichford, Extension Water Quality Specialists, Agronomy Department, Purdue University.
"Current Ag Issues" is produced by the Upper Tippecanoe River and Tri-County Water Quality Projects. The projects are a cooperative effort of Purdue Extension Agronomy, USDA Natural Resources Conservation Service, and the USDA Consolidated Farm Services Agency. 1996-1
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