EVALUATION OF FOLIAGE SPRAY OF SOME RESISTANCE INDUCED CHEMICAL AGENTS TO CONTROL DOWNY MILDEW DISEASE OF CUCUMBER

Abstract

The aim of this study was to evaluate the efficiency of β- Aminobutyric acid, Chitosan, compound, and Salicylic acid as a resistance inducing agents in cucumber plants against downy mildew disease caused by Pseudoperonosporacubensis(Berk. & Curt.)Rostow compared to fosetyl- Al. Results of this study revealed that there was a significant effects of the above agents in reducing the percentage of infected leaves, disease index (DI) and the rate of disease increase (r) compared with control treatment. Results also indicated the prescience of high efficiency of β- Aminobutyric acid when it used as a foliage spray at 2000 µg/ml concentration two days after the artificial inoculation with fungal suspension.Results also improved the efficiency of β- Aminobutyric acid at 1000 µg/ml concentration, Chitosan at 2000 µg/ml concentration asfoliage treatments two days before the inoculation with fungal suspension in reducing the disease infection. The spray of β- Aminobutyric acid on cucumber plants at 2000 µg/ml conc. two days after the inoculation with fungal suspension resulted in reducing infection of downy mildew compared with fungicide or control treatment. Results of this work also revealed that the higher the concentration used the more effects were got compared to lower concentration. Foliar spray with chitosan was superior over the spray with salicylic acid, fosetyl- Al and resulted in decreasing the disease infection percentage, disease index and rate of disease increase and also superior over fosety-Al spray treatment.