STUesday – Corn Rootworm 2014 & 2015 Monitoring Study

Corn Rootworm Monitoring in 2014 & 2015

Objectives

  • Evaluate and monitor corn rootworm protection of Pioneer® brand corn products with the Herculex® RW (HXRW) trait in the central and northern Corn Belt, specifically targeting fields where HXRW has been used in 2 or more consecutive growing seasons.
  • Estimate corn rootworm population levels in fields in the central and northern Corn Belt using Pherocon® AM/NB sticky traps.

Study Descriptions

Study 1: Evaluate and monitor corn rootworm protection

Years: 2014 and 2015
Locations: 136 fields in Iowa, Ill., Ind., Minn., Neb., S.D. and Wis.
Sampling Methods:
  • Targeted fields for sampling with a history of continuous corn and continuous use of HXRW trait (Table 1)
  • All fields were planted with a Pioneer brand corn product with Optimum® AcreMax® 1, Optimum® AcreMax® Xtra, or Optimum® AcreMax® XTreme insect protection in the year that sampling took place.
  • Sampled 10 roots per location (5 were 2-plant clusters)
  • Roots were washed and corn rootworm injury rated using 0-3 Node Injury Scale (NIS)

Table 1. Locations by state and history of fields sampled for evaluation of corn
rootworm protection efficacy in 2014 and 2015.
Field History IL IN IA MN NE SD WI Total
Not Reported 4 2 4 10
2 Years HXRW 9 1 1 2 3 16
3 Years HXRW 9 7 5 3 24
4 Years HXRW 14 3 2 14 1 9 43
5 years HXRW 2 2  2 6
≥ 6 Years HXRW 4 5 11 7 27
Competitive Trait Problem Field 4 1 5
HXRW/Soy Rotation 2 3 5
Total 48 3 20 39 2 1 24 136

Study 2: Estimate corn rootworm population levels

Year: 2015
Locations: 638 fields in Iowa, Ill., Minn., S.D. and Wis.
Sampling Methods:
  • Sticky traps placed in field beginning at blister stage (R2)
  • Sticky traps placed per field: 1 or 6
  • Beetles counted on each trap at 7-day intervals
  • If weekly count averaged more than 50 beetles/trap, trapping was discontinued
  • If the beetle count was below 50 beetles/trap average, new traps were placed in the field and for another 7 days
  • Trapping continued for 4 consecutive weeks, or until traps averaged >50 beetles per trap, whichever came first
Western corn rootworm and northern corn rootworm.

Results

Study 1: Evaluate and monitor corn rootworm protection

  • Corn rootworm injury was low at all locations in the study; average node injury score less than 1.0 (1 node removed).
  • Corn rootworm injury did not differ based on HXRW trait history (Table 2).

Table 2. Average node injury score (NIS) by field history.
Field History    NIS       Locs  
Not Reported 0.03 10
2 Years HXRW 0.08 16
3 Years HXRW 0.05 24
4 Years HXRW 0.09 43
5 years HXRW 0.02 6
6 Years HXRW or more 0.06 27
Competitive trait problem field 0.04 5
HXRW/soy rotation 0.05 5

Study 2: Estimate corn rootworm population levels

  • Corn rootworm population levels were categorized at zero, low, moderate, or high for each sampling location in 2015
    • Zero = no beetles collected
    • Low = traps average <21 beetles/week
    • Moderate = traps average 21-50 beetles in a single week
    • High = traps average >50 beetles in a single week
  • Corn rootworm beetle population levels observed (Figure 1):
    • 3.9% of locations had high populations
    • 11.3% of locations had moderate populations
    • 78.1% of locations had low populations
    • 6.7% of locations had zero adults collected

Figure 1. Population levels observed at corn rootworm beetle trapping locations in 2015.
Population levels observed at corn rootworm beetle trapping locations.

Corn Rootworm Management Considerations

  • Corn rootworm protection of Pioneer® brand corn products with the Herculex® RW trait was extremely consistent across all sampling locations in 2014 and 2015 and was not influenced by HXRW trait use history.
  • Although this study has shown that the HXRW trait remains an effective tool for corn rootworm management, DuPont Pioneer and university research suggests that continuous, uninterrupted use of the same corn rootworm Bt technology can lead to decreased corn rootworm susceptibility to that technology, and may result in reduced product efficacy against these insects.
  • To help maintain the efficacy of Bt corn rootworm products, it is essential to develop a multi-faceted rootworm control management plan.
  • Your DuPont Pioneer Sales Professional or your local Extension professionals can assist you in developing best management practices for your farming operation.
  • Please contact your authorized Pioneer Representative or consult with your local University Extension for more information regarding insect resistance management guidelines, best management practices and to understand whether there has been insect resistance documented in your area.

 

Authors: Jeff Mathesius, Marlin Rice, Ryan French, Brad Van Kooten, Mark Jeschke, and DuPont Pioneer Field Agronomists


Pioneer® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents. The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. 2014-2015 data are based on average of all comparisons made in 774 locations through Oct 20, 2015. Multi-year and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Product responses are variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary.

Herculex® RW HXRW – The Herculex® RW insect protection trait contains proteins that provide enhanced resistance against western corn rootworm, northern corn rootworm, and Mexican corn rootworm.
Herculex® RW Rootworm Protection technology by Dow AgroSciences and Pioneer Hi-Bred. Herculex® and the HX logo are registered trademarks of Dow AgroSciences LLC.
AcreMax® 1

AM1 –  Optimum® AcreMax® 1 Insect Protection System with an integrated corn rootworm refuge solution includes HXX, LL, RR2. Optimum AcreMax 1 products contain the LibertyLink® gene and can be sprayed with Liberty® herbicide. The required corn borer refuge can be planted up to half a mile away.

AcreMax® Xtra

AMX-R –  Optimum® AcreMax® Xtra Insect Protection system with YGCB, HXX, RR2. Contains a single-bag integrated refuge solution for above- and below-ground insects. Do not spray with Liberty®. Not all seeds in the bag are tolerant to Liberty herbicide. In EPA-designated cotton growing counties, a 20% separate corn borer refuge must be planted with Optimum AcreMax Xtra products.

AMX – Optimum® AcreMax® Xtra Insect Protection system with YGCB, HXX, LL, RR2. Contains a single-bag integrated refuge solution for above- and below-ground insects. In EPA-designated cotton growing counties, a 20% separate corn borer refuge must be planted with Optimum AcreMax Xtra products.

AcreMax® XTreme   Herculex(R) XTRA   Agrisure® RW   Yieldgard® Corn Borer   Roundup Ready® Corn 2   LibertyLink®

AMXT (Optimum® AcreMax® XTreme) – Contains a single-bag integrated refuge solution for above- and below-ground insects. The major component contains the Agrisure® RW trait, the YieldGard® Corn Borer gene, and the Herculex® XTRA genes. In EPA-designated cotton growing counties, a 20% separate corn borer refuge must be planted with Optimum AcreMax XTreme products. HXX – Herculex® XTRA contains the Herculex I and Herculex RW genes. YGCB – The YieldGard® Corn Borer gene offers a high level of resistance to European corn borer, southwestern corn borer and southern cornstalk borer; moderate resistance to corn earworm and common stalk borer; and above average resistance to fall armyworm. LL – Contains the LibertyLink® gene for resistance to Liberty® herbicide. RR2 – Contains the Roundup Ready® Corn 2 trait that provides crop safety for over-the-top applications of labeled glyphosate herbicides when applied according to label directions.
Liberty®, LibertyLink® and the Water Droplet Design are registered trademarks of Bayer. YieldGard®, the YieldGard Corn Borer design and Roundup Ready® are registered trademarks used under license from Monsanto Company. Herculex® Insect Protection technology by Dow AgroSciences and Pioneer Hi-Bred. Herculex® and the HX logo are registered trademarks of Dow AgroSciences LLC. Agrisure® is a registered trademark of, and used under license from, a Syngenta Group Company. Agrisure® technology incorporated into these seeds is commercialized under a license from Syngenta Crop Protection AG.