Effects of some commercial products on root and crown rot caused by Phytophthora cactorum in apple cultivation

Root and crown rot caused by Phytophthora cactorum (Lebert & John) Schroeter is one of the most common diseases of apple (Malus domestica) in the world. Due to the negative influences of fungicides on the environment, using other applicable control measures is a plausible way for the management of the disease. The objective of the study was to evaluate the effects of eleven commercial products (bio-pesticides, fertilizers, and activators) on P. cactorum by comparing plant growth parameters (trunk diameter, plant height, number of branches, and root dry weight). Trials were conducted according to a randomized complete block design with three replicates in a greenhouse in 2 consecutive years. In the trials, saplings of Red Chief variety grafted onto MM106 rootstock were planted into pots containing soil mixture inoculated with P. cactorum. Two control groups (negative and positive) were also included in each treatment. Tested commercial products generally had significant (p < 0.01) positive effects on plant growth parameters (trunk diameter, plant height, and root dry weight) by reducing the severity of the disease (50%-93%). Of the tested commercial products, Alexin 95 PS, Companion, Endo Roots Soluble and Subtilex had the highest efficacies. There were negative correlations between plant growth parameters (trunk diameter, plant height, and root dry weight) and severity of the disease, but root dry weight had significant (p < 0.01) correlation (r = -0.56) with the severity of the disease. Present findings revealed that some commercial products could reliably be used against P. cactorum as an alternative to pesticides in apple cultivation.