Mid-May Degree Day Map to Predict Stalk Borer Growth Stage

Published before 2015

Stalkborer growth stage predictor map for Nebraska

Figure 1. Accumulated degree days January 1 - May 15, using a 41°F base. (Source: High Plains Regional Climate Center)

May 18, 2012

Scouting for common stalk borers should be underway across much of southern and east central Nebraska, based on accumulated degree days since January 1. Growers in southeast Nebraska should be determinining the need for treatment, based on scouting numbers.

Based on research at Iowa State University, stalk borer egg hatch begins at about 575 DD and ends at 750 DD. Begin scouting corn when 1,300-1400 DD have accumulated. This corresponds with the beginning of larvae moving out of grassy hosts. Determine the need for treatment when 1,400-1,700 DD have accumulated.

For more information on stalk borer life cycle and scouting recommendations, see the May 11, 2012 CropWatch article, Timetable for Common Stalk Borer Scouting Moves Up.

Robert Wright
Extension Entomologist, Lincoln

Table 1. Degree day requirements for common stalk borer development and management activities (41°F base).
Degree day accumulation from Jan. 1	Event (Egg and larva development)

575	Egg hatch begins
750	Egg hatch complete
1,400	10% of larvae move out of grasses
1,700	50% of larvae move out of grasses
	Event (Pest control)
1,300-1,400	Begin scouting grassy field borders and corn
1,400-1,700	Make insecticide treatment decision in corn

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