Corn Rootworm Update

Corn Rootworm Update

February is often a month of planning for most farm operations, but it also needs to be a time to assess the risks your farm may face in the upcoming season. Corn Root Worm (CRW) is often in the back of every growers’ mind but can easily be forgotten when a grower experience’s multiple years of low pressure. Unfortunately, 2021 is not trending towards a low-pressure environment and CRW shouldn’t be one of those risk factors to let slip by yet again. Every summer, AgriGold agronomist partner with Bayer to monitor CRW beetle counts across the corn belt. Through these combined efforts we have seen beetle populations steadily increase every year since 2015. In comparison, 2020 data shows a large population jump in continuous cornfields vs 2019 (Figure 1 & 2).  In general, continuous corn fields are at the highest risk levels we have seen since 2010.

Figure 1 & 2

2020: CORN ROOTWORM TRAP COUNT DATA SUMMARY

  • Variable CRW populations were observed, which suggest that environment and management affected CRW pressure

  • 22% of corn fields exceeded the economic threshold of 2 beetles/trap/day

  • 8% of the corn fields were on the brink of approaching threshold levels

  • Corn followed by corn had higher average max daily counts than first year corn (2.79 vs .42 beetles/trap/day)

  • 33% of continuous corn fields exceeded the economic threshold while less than 3.9% of first year corn exceeded the threshold

  • Counts of 0 were recorded in 21% of corn fields sampled across the corn belt

  • Soybean field counts were low, 29% of fields captured 0 adults & fewer than 4.7% of the fields exceeded the threshold

2021: MANAGEMENT CONSIDERATIONS

  1. Know your risk by scouting your own fields
    • Utilize sticky traps during reproductive stages
    • Threshold is 2 beetles per trap per day
  2. Rotate away from corn when thresholds are exceeded
  3. Control grass & volunteer corn in soybean fields
  4. Utilize multiple effective MOA’s for control
    • Use only pyramided traits
    • Rotate trait proteins every season
    • Incorporate insecticides in furrow
  5. Lower adult beetle populations with insecticide
    • Threshold is .7 -1 beetle per plant
    • Timing is critical, may require multiple apps
    • Utilize dual MOA insecticides

2021: WHAT REGIONS ARE MOST AT RISK

Using 2020 Corn Rootworm Beetle Counts to Assess the Risk of Economic Injury in 2021.

2021 Regions at risk

 

Sources:

  1. Bayer Crop Science, 2020 Corn Rootworm Trap Count Data Research Report