A comparison of motorised knapsack mistblower, medium volume application, and spinning disk, very low volume application, of Helicoverpa armigera nuclear polyhedrosis virus on cotton in Thailand
Ma. Parnell et al., A comparison of motorised knapsack mistblower, medium volume application, and spinning disk, very low volume application, of Helicoverpa armigera nuclear polyhedrosis virus on cotton in Thailand, CROP PROT, 18(4), 1999, pp. 259-265
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 co
tton in September and October 1995 to investigate the efficacy of spinning
disk spray application, at very low volume (VLV) rates, compared to motoris
ed knapsack mistblower spray application at medium volume (MV) rates. Trial
s 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 pe
rformance 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 l
eaves were made. The results of leaf sample bioassays indicated that VLV ap
plication by a spinning disk sprayer gave better control than did MV applic
ation by a mistblower. (C) 1999 Elsevier Science Ltd. All rights reserved.