International Journal of Pest Management (2005) 51, 63-70

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R.K. Mensah, W. Liang, D. Gibbs, R. Coates and D. Johnson (2005)
Evaluation of nC27 petroleum spray oil for activity against Helicoverpa spp. on commercial cotton fields in Australia
International Journal of Pest Management 51 (1), 63-70
Abstract: We determined the efficacy of an nC27 petroleum spray oil (PSO) (Caltex Canopy®) against Helicoverpa spp. on commercial cotton crops. Cotton plants treated with 1 - 5% (v/v) of the nC27 PSO were better at deterring oviposition by Helicoverpa spp. than benchmark synthetic insecticides. Applications of 2 - 5% (v/v) PSO provided similar efficacy to the conventional insecticides against very small and small (first - third instar) and medium to large (fourth - fifth instar) Helicoverpa spp. larvae, but the efficacy of 1% (v/v) PSO against medium and large larvae was significantly lower than that of the conventional insecticides. Thus, the optimum rate of application of the PSO was determined to be 2% (v/v). The study also showed that the PSO was more efficacious against the very small and small larvae than the medium and large larvae. The oil kills larvae mostly through direct contact but some activity arises through ingestion of oil residues. In this study, the mortality of Helicoverpa spp. larvae arising from ingestion of oil residues lasted for 2 - 3 days after treatment. Thus the main mode of action of the PSO remained through suffocation of the larvae. When the PSO was applied during the early to mid cotton season (October to mid-January) it controlled Helicoverpa spp., below the recommended economic threshold of two larvae per m. In contrast, when the PSO was applied during the mid and late cotton season (mid-January onwards) economically acceptable control of Helicoverpa spp. was not achieved. This was most likely due to the fact that adequate coverage of PSO sprays on cotton plants was achieved only early in the season when plants were smaller. In the mid and late season, when the cotton plants were bigger, adequate coverage was not achieved. During this period, the PSO may have to be used as a mixture with pesticides to control Helicoverpa spp. effectively. In conclusion, the nC27 PSO was efficacious against Helicoverpa spp. larvae and could therefore be a useful tool to complement IPM programmes in cotton crops.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Robert K. Mensah, Weiguang Liang

Research topic(s) for pests/diseases/weeds:
control - general

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Helicoverpa armigera Cotton (Gossypium)