Preplant Root Treatments to Reduce the Incidence ofPhytophthoraSpecies on Dormant Apple Rootstocks

In trials over a 6-yr period, roots of dormant MM.106 apple (Malus domestica) rootstocks were soaked in aqueous fungicide suspensions before planting to reduce the incidence of naturally occurring inoculum of Phytophthora cactorum and P. cambivora, causal agents of Phytophthora crown rot. Initially, roots were soaked for 10 min or 1 hr in 1,000 mg/L of captafol, copper hydroxide, mancozeb, or metalaxyl or in 1.05% sodium hypochlorite. In later trials, metalaxyl and copper hydroxide were compared with etridiazole, fosetyl-Al, and oxadixyl (...)