Control of Early Blight of Tomato Caused by Alternaria Solani and Screening of Tomato Varieties against the Pathogen

Early blight is a common disease of tomato, which is caused by Alternaria solani.

This work was accompanied to find an alternative to chemical fungicides and to screen tomato varieties against Alternaria solani.

The infected leaves were collected from five tomato fields of Shere-e-Bangla Agricultural University, Dhaka and were cultured for the identification of the infectious fungus and The phytobiocidal role of six plants against Alternaria solani was evaluated in vitro model.

Alternaria solani was identified as the infectious fungus. The growth of the test fungi Trichoderma spp. viz., Trichoderma viride, T. harzianum collected form NAMDEC and Trichoderma sp collected from field of BCSIR was monitored as optimum P_H. All the selected Trichoderma spp. were antagonistic to A. solani. Antagonistic capacity of the Trichoderma spp. was tested by dual culture, volatile as well as non-volatile method. It was observed, T. viride was most effective in the reduction process of A. solani and T. harzianum. T. viride also showed highest inhibition in volatile and non-volatile trials. Six plant extracts viz., Adhatoda vasica (Nees), Azadirachta indica (A Juss). Ocimujm sanctum (L), Allium sativum (L), Datura metal (Linn) and Zingiber officinale (Rose) were selected to evaluate their in vitro efficacy of 5%, 10% and 20% concentration against the A. solani. Allium sativum was the most effective one against A. solani, followed by Azadirachta indica. The efficacy of five fungicides viz., Bavistin 50WP, Mancozeb 80WP, Indofil M-45, Sulcox 50WP and Tall 25EC were evaluated for their fungitoxicity against the A. solani at 100, 200,100, 600 and 800 ppm. Tall 25EC was the most effective fungicide against Alternaria solani followed by Mancozeb 80WP. After screening the five tomato varieties against A. solani, it was revealed that BARI Tomato-9 had the highest Percentage of Disease Index (PDI) and the leaf of BARI Tomato-7 had the lowest Percentage of Disease Index (PDI).

The extract of Allium sativum was effective to control Alternaria solani at prescribed concentration. The highest PDI was found in BARI tomato-9 against Alternaria solani.