Efficacy of Kaolin-Based Particle Films to Control Apple Diseases

Studies were conducted from 1997 to 1999 to evaluate the effect of processed kaolin-based particle film applications on the incidence and severity of apple (Malus domestica Borkh.) diseases. Greenhouse and field studies demonstrated that pre-emptive application of hydrophobic and hydrophilic particles reduced the incidence of fire blight (Erwinia amylovora (Burrill) Winslow et al.) in blossoms and injured shoots. Hydrophobic and hydrophilic particles suppressed sooty blotch (Gloeodes pomigena (Schwein.)) and flyspeck (Schizothyrium pomi (Mont. & Fr.) Arx: anamorph Zygophiala jamaicensis Mason) to levels equivalent to conventional fungicides. In field studies, apple scab (Venturia inaequalis (Cooke) Wint.: anamorph Spilocaea pomi Fr.) was not suppressed by hydrophilic particles. Hydrophilic particles did not interfere with the action of conventional fungicides or the activity of calcium hydroxide to suppress apple scab. Hydrophilic particles did reduce powdery mildew (Podosphaera leucotricha (Ell. & Ev.) E.S. Salmon (anamorph Oidium farinosum Cooke)) russetting on fruit, but leaf infection was extensive.