Application of some Epidermal Coating Antitranspirant Products for Controlling Wheat Leaf Rust Caused by Puccinia triticin

This study aimed to evaluate the effect of spraying three epidermal coating antitranspirant products namely kaolin (Ka), magnesium carbonate (MgCO₃) and fulvic acid (FA) at different concentrations before rust inoculation on controlling wheat leaf rust disease. Results in seedling stage indicated that higher concentration of kaolin (6%) followed by fulvic acid (0.06) increased incubation period of cv. Sakha 93 compared with control treatment. However, opposite result was observed in case of cv. Sids 1, where MgCO₃ (6%) was the best one. The higher three concentrations of tested products decreased
the number of pustules/cm² or seedling leaf area. Fulvic acid was the most effective one compared with kaolin and MgCO_3..In case of pustule size, kaolin reduced the pustule size followed by MgCO₃ , while fulvic acid was the lowest one comparing with infected control. Scanning electron micrographs of wheat seedling leaves sprayed 24 h before inoculation showed deformed uredospore shape, abnormal germ tube and appressoria. Also, alter topography of wheat leaf surface compared with untreated leaves. Cross section in sprayed fulvic acid treatment showed increase in the thickness of spongy cell walls comparing with control treatment. Results obtained on wheat cv. Sids 1 adult plants sprayed 3, 7 and 10 days before inoculation (dbi) indicated that none of the tested products used significantly increased incubation period or latent period. On the other hand, concentrations and days before inoculation significantly affected these two parameters. Data obtained also indicated that area under disease progress curve (AUDPC) was decreased by application of these products and their concentrations, while number of pustules/cm₂ significantly affected by the tested product, dbi and the interaction between them. Also, these products changed the infection type from susceptible to moderately susceptible, moderately resistant or resistant according to the product used, concentration and dbi. These results were confirmed by decreasing rust severity and average coefficient of infection in different degrees according to the product used, concentration and dbi. Antitranspirant increased the plant pigments in treated plants compared to untreated infected ones.