Control of Phytophthora crown and root rot of apple trees with fosetyl‐aluminium in new plantings

Fosetyl‐aluminium applied as a foliar spray, monoammonium phosphate (MAP) as a planting hole treatment, and a combination of MAP and Enterobacter aerogenes (Kruse) Hornaeche & Edwards (B8) were evaluated for eight years for control of Phytophthora cactorum (Lebert & Cohn) Schroet, crown and root not in newly planted and artificially infected Macspur apple trees on MM.106 rootstock in the Okanagan valley of British Columbia. Fosetyl‐aluminium completely controlled the disease, and increased growth and fruit yield. The combination of planting hole treatment with MAP plus annual drench applications of strain B8 significantly increased trunk cross‐sectional area for the first three years after planting. The application of MAP alone did not have any effect on the disease, growth, or fruit yield of apple trees.