A comparison of motorised knapsack mistblower, medium volume application, and spinning disk, very low application, of Helicoverpa armigera nuclear polyhedrosis virus on cotton in Thailand
1999
Parnell, M.A. | King, W.J. | Jones, K.A. | Ketunuti, U. | Wetchakit, D.
A wettable powder formulation of Helicoverpa armigera nuclear polyhedrosis virus (NPV) was applied against larvae of the cotton bollworm (Helicoverpa armigera) (Hubner) in Thailand. Field trials were carried out on rainfed cotton in September and October 1995 to investigate the efficacy of spinning disk spray application, at very low volume (VLV) rates, compared to motorised knapsack mistblower spray application at medium volume (MV) rates. Trials were done to ascertain if any control benefits would arise from using VLV spinning disk sprayers as an alternative application method to mistblower sprayers (at medium volume) commonly used on cotton in Thailand. Sprayer performance was assessed by bioassay of leaves sampled from spinning disk VLV and mistblower MV spray application plots. Volumes of spray deposited were determined and measurements of droplets deposited on targets attached to leaves were made. The results of leaf sample bioassays indicated that VLV application by a spinning disk sprayer gave better control than did MV application by a mistblower.
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