Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 21, 2001
Publication Date: June 1, 2001
Citation: Knight, A.L., Christianson Jr, B.A., Unruh, T.R., Puterka, G.J., Glenn, D.M. 2001. Impacts of seasonal kaolin particle films on apple pest management. The Canadian Entomologist. 133:413-428. Interpretive Summary: Studies were conducted from 1997-1999 to evaluate the seasonal impact of kaolin-based particle films on apple pest management. The effect of season-long applications of particle films was highly dependent on the pest species. Particle films were very effective in reducing the population density of white apple leafhopper and direct fruit injury by both the codling moth and leafrollers. However, some pest species densities were higher in particle film treated plots such as the western tentiform leafminer, rosy apple aphid, and San Jose Scale. The impact of particle film on the population densities of green aphids and mullein bug were variable; and stink bug populations appeared to be unaffected by particle film applications. Biological control by specialized parasitoids and generalist predators appeared to be negatively impacted by particle film spray programs. No differences in pest densities occurred in plots treated for one vs two consecutive years. However, the density of phytophagous mites was significantly higher during 1999 in plots treated only in 1998. The effects of particle film on fruit quality parameters such as size, sugar content, and firmness were unclear.
Technical Abstract: Studies were conducted from 1997-1999 to evaluate the seasonal impact of kaolin-based particle films on apple pest management. Densities of western tentiform leafminer were significantly higher and percent parasitism was generally lower in treated vs untreated plots. The effect of particle film treatments on the green apple aphid was variable between orchards, however populations of rosy apple aphid were higher in treated vs untreated plots. Particle film treatments reduced the mean density of the white apple leafhopper and the density of spiders compared with untreated plots. Fruit injury by codling moth and fruit tree leafroller were significantly reduced in the treated vs untreated plots. The effects of particle film on the mullein bug were variable between orchards and years. Stink bug density and related fruit injury were unaffected by treatments. Fruit infestation by San Jose Scale was significantly higher in treated vs untreated plots in 1998; however, a supplemental chlorpyrifos spray controlled scale in 1999. Discontinuing applications at mid-season in 1998 reduced the number of aphid-infested leaves and increased fruit injury by leafroller compared with a full-season program. No differences in pest densities occurred in plots treated for one vs two consecutive years. However, the density of phytophagous mites was significantly higher during 1999 in plots treated only in 1998. The effects of particle film on fruit size, percent soluble solids and fruit pressure were variable between years and treatments.