Management of Tomato Leaf Spot Caused by Alternaria tenuissima Wiltshire using Salicylic Acid and Agrileen
Alternaria tenuissima was isolated from tomato showing symptoms of leaf spot disease cultivated under greenhouse conditions from Asir region, Saudi Arabia. The ability of salicylic acid (SA) and the newly prepared bioactive matter "Agrileen" (AG) to suppress the leaf spot disease of tomato was evaluated. Exogenous application of SA (0.5 and 1.0 mM) or AG (2.5 and 5%) enhanced the growth and plant yield of tomato in addition to the reduction of infection with A. tenuissima. Photosynthetic pigments, total proteins, free proline and the relative water content of leaves were also enhanced when either SA or AG was applied. The protein pattern showed an increase in band intensity in plants treated with SA that express the increase in gene expression involved in resistance against stress conditions. The results confirmed that the application of SA or AG could protect tomato plants against A. tenuissima infection either through the direct strength of the defense system and a reduction of the severity of the pathogen.