Wow, the last week of heat has really driven up the black cutworm development model. See the following map, most of Indiana should NOW be scouting emerged cornfields, especially in high-risk fields. Significant black cutworm leaf feeding and cutting of corn seedling begins about 300 heat units (base 50ºF). The following videos may be helpful, especially to understand how many variables must “line-up” for black cutworm to be an economic problem.

Black cutworm larval development refer to article in Issue 4, April 24, 2015

Black cutworm (Agrotis ipsilon) moths are “pushed” into the Midwest every spring from the Southwest, and females are attracted to certain fields, e.g., chickweed laden, for egg-laying. Cooperators throughout Indiana monitor their annual arrival, and density, with pheromone traps. Once black cutworm hatch, their larval development is dependent on a food source and heat. They say “timing is everything,” and this is certainly true with black cutworm arrival, weed control, larval development, and planting date. In today’s fast-moving pace of spring planting, corn usually “outgrows” the cutworm, before larger larvae can cause significant damage.

Black cutworm (Agrotis ipsilon), a long-time corn pest in the Midwest, is generally a problem today only in late-planted corn. Timing of winter-annual weed control, e.g., chickweed, is important concerning black cutworm egg-laying and larval development. Some traited corn and seed-applied insecticides have suppressive activity against small cutworm but not larger larvae. Scouting the field is the only way to know if problems exist, especially catching the damage early before plants are killed or delayed in growth. Needed rescue foliar insecticides, if applied in a timely manner, are very effective in controlling black cutworm.

• Thanks to the pheromone trap cooperators!
• Plenty of intensive moth captures this season.
• According to heat unit accumulations, NOW is the time to be scouting!
• Get muddy in the field, replanting is not a good option at this point.

Every spring, dozens of cooperators throughout the state put forth considerable effort in trapping for the arrival and intensity of black cutworm moths. I’m personally indebted to these faithful bug counters, hoping you also appreciate their efforts as reported in the “Black Cutworm Adult Pheromone Trap Report.” If you recognize a name or two on this list of reporters, by county, please thank them!

This year’s trap total, compared to the previous four, looks mediocre. Within these averages are many intensive moth captures over the six weeks of monitoring, follow up this moth arrival with larval damage scouting. Using the larval development model (see the accompanying “Black Cutworm Development Map”) it allows us to alert pest managers to be scouting emerging corn.

Black Cutworm Moth Trap Comparisons 2011-2015

A call from Troy Jenkins, North Central Co-op, this past week alerted us to the fact that Asiatic garden beetle grubs are making their presence felt in course-textured soils of fields in north central and northeastern counties. Seed applied insecticides have little effect in preventing these grubs from feeding on corn roots, more importantly the mesocotyl. Unfortunately there is no rescue treatment available. Damaged plants, if growing points aren’t compromised, may recover somewhat if grubs soon pupate (i.e., stop feeding) and ample moisture is available. Don’t let the size of the small grubs fool you, they are like grubs on steroids!

Japanses beetle (left) and Asiatic garden beetle (right) grubs compared in size.

Japanese beetle (left) and Asiatic garden beetle (right) heads compared, NOTE the small, white "pouch" on the AGB grub.

Wk 1 = 4/2/15 - 4/8/15; Wk 2 = 4/9/15 - 4/15/15; Wk 3 = 4/16/15 - 4/22/15; Wk 4 = 4/23/15-4/29/15;
Wk 5 = 4/30/15-5/6/15; Wk 6 = 5/7/15-5/13/15