Effects of flooding, rootstocks and fungicides on Phytophthora crown rot of almonds

Abstract

Flooding for 2 days in the absence of Phytophthora cambivora either killed or severely retarded the growth of seedling Chellaston almonds and the peach rootstock Nemaguard. Flooding either before or after inoculation favoured the development of P. cambivora in Chellaston almond seedlings. Both Chellaston and Mission were more susceptible than Nemaguard to P. cambivora. A water suspension of 250 ml of metalaxyl at 333 or 1000 mg a.i./litre in hibited the development of lesions on stems if applied as a drench before or at the time of inoculation, but not when applied 3 or 7 days later.