Assessments of formulated bacterial strains against crown and root rot of pistachio trees

Gummosis (Crown and root rot) is the most important disease of pistachio trees caused by different species of Phytophthora which destroy significant numbers of fertile and non-fertile trees each year in Iran. Different approaches have been applied to reduce the severity and incidence of the disease. In recent years, biological control as an eco-friendly approach has been increased in the world. The effectiveness of Talk powder and Wheat bran formulations of five Pseudomonas strains (T17-4, VUPF760, VUPF5, VUPF506, and CHA0) was assessed on seedlings inoculated with Phytophthora drechsleri under greenhouse conditions. The highest and lowest reduction rates of disease severity belonged to VUPF760 and VUPF506 with 55 and 11%, respectively compared to the control and other treatments. Seedling inoculated with bacterial strains had higher heights, fresh and dry weights of shoot and roots. VUPF5 increased the ratios of height, fresh and dry weight of shoot and root by 1.4, 1.3, 1.1, 1.2, and 1.1 respectively, compared to non-inoculated control seedlings.