Impacts of seasonal kaolin particle films on apple pest management.
The impact of multiple applications of the kaolin-based particle film M96-018 on the population density of selected pests of apple (Malus domestica [M. pumila]) and their natural enemy populations were measured in several Washington State (USA) orchards from 1997 to 1999. Densities of western tentiform leafminer (Phyllonorycter elmaella) were significantly higher and percentage parasitism was generally lower in treated plots than in untreated plots. The effect of M96-018 on green aphids (Aphis spp.) was variable between orchards; however, populations of rosy apple aphid (Dysaphis plantaginea) were higher in treated plots than in untreated plots. M96-018 reduced the mean density of the white apple leafhopper (Typhlocyba pomaria) and the density of spiders (Araneae) compared with untreated plots. Fruit injury by codling moth (Cydia pomonella) and fruittree leafroller (Archips argyrospilus) was significantly reduced in the treated plots compared with the untreated plots. The effect of M96-018 on the mullein bug (Campylomma verbasci) was variable between orchards and years. Stink bug (Hemiptera: Pentatomidae) density and related fruit injury were unaffected by M96-018. Fruit infestation by San Jose scale (Quadraspidiotus perniciosus [Diaspidiotus perniciosus]) was significantly higher in treated plots than in untreated plots. Discontinuing applications of M96-018 at mid-season reduced the number of aphid-infested leaves and increased fruit injury by leafroller compared with a full-season programme. No differences in pest densities occurred in plots treated for one than two consecutive years; however, the density of phytophagous mites (Acari: Tetranychidae) was significantly higher the subsequent year after plots were treated with M96-018.