The Effect of Foliar Spray Application with Salicylic Acid and Bacillus subtilis AB1 on The Growth and Protection of Grapevine Bushes from Powdery Mildew Disease Caused by the Fungal Pathogen Uncinula necator

Abstract

El-Mosto, E., Z. Hassani and M. Abou Shaar. 2024. The Effect of Foliar Spray Application with Salicylic Acid and Bacillus subtilis AB1 on The Growth and Protection of Grapevine Bushes from Powdery Mildew Disease Caused by the Fungal Pathogen Uncinula necator. Arab Journal of Plant Protection, 42(3): 328-334. https://doi.org/10.22268/AJPP-001244 This study was conducted to evaluate the effect of foliar spray with three concentrations of salicylic acid (100, 200 and 300 mg/L), Bacillus subtilis AB1 at a concentration 2×106 cfu/ml, and the combined mutual effect of both, compared with a farmer's control on vegetative growth, clusters weight, productivity, and reduction of powdery mildew disease spread on grape vines. The growth length was significantly increased (140.7 cm) by applying the foliar spray of the bacteria + salicylic acid (200 mg/L) compared to the two treatments of salicylic acid 100 mg/L and the farmer's control (55.2 and 82.5 cm, respectively), whereas no significant differences were obtained between them and the rest of the treatments. The foliar spray with the treatment of both components (bacteria + salicylic acid 300 mg/L) was superior to all studied concentrations in relation to the average leaf surface area, clusters weight and productivity. All studied treatments reduced the severity of powdery mildew infection on leaves, except for salicylic acid at 200 mg/L (0.19) and no significant differences were recorded between all treatments (0.11-0.12) except for the two treatments (bacteria alone and farmer's control (0.15 and 0.14), respectively, in terms of reducing disease the severity of infection on fruit clusters. Keywords: Grapevine, salicylic acid, Bacillus subtilis AB1, vegetative growth, productivity, powdery mildew