Fungal Diseases of Persian Walnut in Uzbekistan and their Control

Abstract

Surveys have been made in Persian walnut plantations and groves in 2018 and 2019 in three regions of Uzbekistan. It has been revealed that anthracnose caused by Gnomonia leptostyla had the widest distribution among all diseases registered. Walnut varieties have varied significantly on resistance to the disease. Occurrence of downy mildew (Microstroma juglandis) was much lesser. Shaggy bracket fungus (Inonotus hispidus), the cause of white heart rot has been more or less common on walnut trees. Two-years field trials have been carried out to determine biologic efficacy of several fungicides against anthracnose on leaves, twigs and fruits of walnut. Difen Super 55% WP, Syllit 40% SC, Falkon 46% EC and Score 25% EC have revealed the highest efficacy (90% to 100%). Efficacies of lower rates of Syllit 40% SC and Falcon 46% EC, and Curzate WP, Coritus 50% WDG and Cresoxin 50% WDG were between 74.7% and 88.8%, while that of Myseb M-45 WP was under 65%; biological fungicides Phytolavin Water Soluble Concentrate and Sporagin WSC have shown efficacies between 20.9% and 45.0%.