Corn Insect Update 5/9/19

Originally Posted in the Wisconsin Pest Bulletin

Volume 64 Number 2 Date 05/09/2019

BLACK CUTWORM – A weekend storm front on May 5-6 brought additional flights of black cutworms northward into the state. DATCP’s 44 monitoring locations collected 267 moths, with 10 sites registering significant counts of nine or more moths in two nights. The highest trap count for the week was 20 moths near Hampden in Columbia County. Pheromone traps have captured a cumulative total of 758 specimens since the first moth appeared on April 4.

The black cutworm counts recorded this spring are considered moderate in comparison to captures in high-moth years,though delayed spring field preparation and early-season weed growth have provided highly favorable egg laying habitat for female moths arriving over the past 4-5 weeks.Based on the first major BCW migration event on April 12 and the expected slow accumulation of degree days over the next two weeks,the earliest peak corn cutting window will not open until May 27 near Beloit, May 29 near Madison, and June 4 near Hancock. However, the second wave of significant captures recorded in the past week signals the cutting period could be protracted, with a second peak damage period starting around June 6.

The late start to 2019 planting season and the consistent moth migrations documented since mid-April indicate a high risk of BCW damage to vegetative corn this spring.

*Mustang Maxx Preventative or Rescue at 2.5 oz – 3 oz /acre. Hero Preventative or Rescue at 4 oz/acre.*

SEEDCORN MAGGOT -Emergence of first-generation flies from overwintered pupae has peaked.Peak fly emergence theoretically occurred last week across southern Wisconsin with the accumulation of 360 degree days (sine base 39°F), and is forecast for the Appleton, Hancock and Tomah areas of central Wisconsin in the week ahead Heavy egg laying is likely during this time. Cool, moist soil conditions prevalent statewide are less than optimal for rapid seed germination and highly favorable for seedcorn maggot (SCM) infestation, increasing the risk of maggot damage to susceptible crops such as corn and soybean seeds and seedlings. Planting as close as possible to the ‘fly-free’ period between the first and second generations can reduce risk and is the primary cultural control for this spring soil insect pest.If SCM infestation is suspected, dig up apparent seed skips in the row and examine seed for evidence of damage. Cutworms, wireworms, and white grubs are other insects that can contribute to stand loss.

* Make sure your growers have either Capture LFR or Ethos XB in the Starter Fertilizer tank to help against Seed corn Maggot!*

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