Bacillus subtilis QST 713, copper hydroxide, and their tank mixes for control of bacterial citrus canker in Saudi Arabia

Abstract

Citation: Ibrahim YE, Saleh AA, El_Komy MH, Al-Saleh MA. 2016. Bacillus subtilis QST 713, copper hydroxide, and their tank mixes for control of bacterial citrus canker in Saudi Arabia. J Cit Pathol. iocv_journalcitruspathology_30994. ______________________________________________________________________________________________________________________________ Abstract Citrus bacterial canker (CBC) is a devastating disease that affects production of almost all commercial citrus cultivars in subtropical citrus growing regions worldwide. In this study, the effect of monthly foliar sprays of wettable powder formulation Serenade® MAX of Bacillus subtilis QST 713, alone or as tank mixes with copper hydroxide, on CBC disease development was evaluated under greenhouse and open air nursery conditions. The Serenade® MAX as a tank mix with copper hydroxide significantly reduced the disease severity and incidence, followed by the copper hydroxide treatment, compared to the control. The disease incidence on leaves of inoculated trees treated with a combination of copper with Serenade® MAX was never higher than 19%, whereas the disease incidence reached 43% for non-sprayed trees. It was possible to reduce the number of copper sprays down to 6 sprays per season when it was mixed with the bio-fungicide Serenade® MAX to effectively control CBC, compared with 8 sprays of copper hydroxide alone per season. Based on our results, the application of Serenade® MAX may have not only the potential for CBC management in conjunction with copper hydroxide or other disease control measures, but may also reduce the frequency or rate of copper sprays in citrus groves.