Bacillus Thuringiensis for Use against Armyworm, Pseudaletia unipuncta (Lepidoptera: Noctuidae), On Wheat

Abstract

Spray table tests with Bacillus thuringiensis (Javelin WG) on wheat leaves against armyworm, Pseudaletia unipuncta (Haworth), showed that 1st and 3rd instars had LC50s of 0.09 and 0.55 kg per ha, respectively, 7 d after treatment. Wheat sprayed in the field in 1995 with Javelin WG at rates of 0, 0.28, 0.56, 1.12, and 2.24 kg per ha resulted in 82% and 62% 1st instar mortality 7 d after feeding on treated flag and middle leaves, respectively, at the highest rate. In 1996, the test was repeated and mortality was higher, with 98, 97, and 92.9% 1st instar mortality 7 d after feeding on treated flag, middle, and bottom leaves, respectively, at the highest rate. Third instars were less susceptible, with 89, 81, and 76% mortality 7 d after treatment at the highest rate on flag, middle, and bottom leaves, respectively. Leaf position had little effect on spray droplet numbers or mortality of larvae fed treated leaves, indicating that spray distribution was relatively even throughout the wheat canopy.