Forecasting Stalk Borer Growth Stage - UNL CropWatch, May 23, 2013

Forecasting Stalk Borer Growth Stage - UNL CropWatch, May 23, 2013

May 23, 2013

GDD map indicating stalk borer development

Figure 1. Accumulated degree days from January 1 to May 20, using a 41°F base. (Source: Al Dutcher and the High Plains Regional Climate Center)

Stalk borer hatch and migration to new hosts can be predicted using degree days (DD). 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.

This week's map indicates that stalk borer eggs have hatched across most of the state. Be ready to scout for larvae when 1400 degree day accumulation has occurred.

Robert Wright
UNL Extension Entomologist

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)


Egg hatch begins


Egg hatch complete


10% of larvae move out of grasses


50% of larvae move out of grasses

  Event (Pest control)


Begin scouting grassy field borders and corn


Make insecticide treatment decision in corn


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