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Relating the Occurrence of Bollworm, Helicoverpa zea (Boddie), Larvae to Louisiana Crop Phenology

E.A. Peters, D.R. Cook, and B.R. Leonard


Bollworm, Helicoverpa zea (Boddie), larval populations were monitored in several field crops throughout the 2002 and 2003 growing seasons (Jun to Sep) at the Macon Ridge Research Station near Winnsboro, Louisiana (Franklin parish). Larval populations were monitored weekly by counting the number of larvae in each of seven different host crops including non-Bollgard cotton,Bollgard cotton, Bollgard II cotton (2003), maturity group (MG) 4 soybean, MG 6 soybean, grain sorghum, and non-Bacillus thuringiensis (Bt) field corn. Monitoring began in early June and was terminated in early Sep. Peak densities in field corn were observed during the R2-R5 growth stages, in grain sorghum during the 4-9 growth stages, in MG 6 soybean during the R1-R6 growth stages, in non-Bollgard cotton during the 7 NAWF-1 NACB stages, and in Bollgard cotton from the 5 NAWF-10 NACB growth stages. No larvae were observed in MG 4 soybean (2002 and 2003) or in Bollgard II cotton (2003). The only alternate host crop that exhibited similar temporal synchrony with bollworm larvae in Bollgard cotton was MG 6 soybean, indicating the possibility of including it in an IRM strategy for Bollgard cotton.

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Document last modified 04/27/04