Corn Rootworm Egg Hatch Behind Schedule this Year

Jun 22, 2022

By Ashley Dean and Erin Hodgson

Corn rootworm egg hatch in Iowa typically occurs from late May to the middle of June, with an average peak hatching date of June 6 in central Iowa. Even with recent warm temperatures, hatching is a bit delayed this year due to cool spring temperatures. Development is driven by soil temperature and measured by growing degree days (GDDs). Research suggests about 50% of egg hatch occurs between 684-767 accumulated GDDs (since January 1; base 52°F, soil). Many areas have reached peak corn rootworm egg hatch, and the northern portion of the state could experience peak hatch within a week (Figure 1).

Figure 1. Accumulated soil degree days (base 52°F) in Iowa as of June 20, 2022. Expect 50% egg hatch of corn rootworm between 684-767 degree days

Figure 1. Accumulated soil degree days (base 52°F) in Iowa as of June 20, 2022. Expect 50% egg hatch of corn rootworm between 684-767 degree days.

To predict corn rootworm egg hatch for your area based on degree day accumulation, use the Iowa State Agronomy Environmental Mesonet website. Set the start date to January 1 of the current year, use the current date for the end date, and make sure the plot parameter is set to “soil growing degree days (base = 52).”

A severe corn rootworm larval infestation can destroy nodes 4-6; each node has approximately 10 nodal roots. Root pruning interferes with water and nutrient uptake and makes the plant unstable (Figure 2). Recent research predicts a 15% yield loss for every node pruned back to 1 ½ inches. Prolonged drought can exacerbate root injury and cause additional yield loss.

Figure 2. Severe root pruning by corn rootworm larvae can dramatically impact yield

Figure 2. Severe root pruning by corn rootworm larvae can dramatically impact yield.

Regardless of agronomic practices used to suppress corn rootworm (e.g., crop rotation, Bt hybrids, or soil-applied insecticides), every corn field should be scouted for corn rootworm root injury. Continuous corn fields and areas with Bt trait performance issues are the highest priority for inspection. It is ideal to look at corn roots 10-14 days after peak egg hatch because the feeding injury will be fresh. On some hybrids, corn roots can grow back and make it difficult to assess feeding injury later in the season. Assess corn rootworm feeding and adjust management strategies if the average injury is above 0.5 on the ISU 0 to 3 Node Injury Scale. Also consider monitoring for adult corn rootworm to supplement root injury assessments.

To refresh your root injury assessment skills, consider attending one of the seven corn rootworm demonstrations occurring in Iowa this summer.

Source : iastate.edu

Video: Why Invest in Canada’s Seed Future? | On The Brink: Episode 3

Darcy Unger just invested millions to build a brand-new seed plant on his farm in Stonewall, Manitoba so when it’s time for his sons to take over, they have the tools they need to succeed.

Right now, 95% of the genetics they’ll be growing come from Canadian plant breeders.

That number matters.

When fusarium hit Western Canada in the late 90s, it was Canadian breeders who responded, because they understood Canadian conditions. That ability to react quickly to what’s happening on Canadian farms is exactly what’s at risk when breeding programs lose funding.

For farmers like Darcy, who have made generational investments based on the assumption that better genetics will keep coming, the stakes are direct and personal.

We’re on the brink of decisions that will shape our agricultural future for not only our generation, but also the ones to come.

What direction will we choose?

On The Brink is a year-long video series traveling across Canada to meet the researchers, breeders, farmers, seed companies, and policymakers shaping the future of Canadian plant breeding. Each week, a new story. Each story, a piece of the bigger picture.

Episode 3 is above. Follow Seed World Canada to catch every episode, and tell us: Do you think the next generation will have the tools they need to success when they takeover? How is the future going to look?