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 byAlternaria solani.This work was accompanied to find an alternative to chemical fungicides and to screen tomato varieties againstAlternaria 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 againstAlternaria solaniwas evaluatedin vitromodel.Alternaria solaniwas identified as the infectious fungus. The growth of the test fungiTrichodermaspp.viz.,Trichoderma viride,T. harzianumcollected form NAMDEC andTrichodermasp collected from field of BCSIR was monitored as optimum PH. All the selectedTrichodermaspp. were antagonistic toA. solani.Antagonistic capacity of theTrichodermaspp. was tested by dual culture, volatile as well as non-volatile method. It was observed,T. viridewas most effective in the reduction process ofA. solaniandT. harzianum.T.viridealso showed highest inhibition in volatile and non-volatile trials. Six plant extractsviz.,Adhatoda vasica(Nees),Azadirachta indica(A Juss).Ocimujm sanctum(L),Allium sativum(L),Datura metal(Linn) andZingiber officinale(Rose) were selected to evaluate theirin vitroefficacy of 5%, 10% and 20% concentration against theA. solani.Allium sativumwas the most effective one againstA. solani, followed byAzadirachta indica. The efficacy of five fungicidesviz., Bavistin 50WP, Mancozeb 80WP, Indofil M-45, Sulcox 50WP and Tall 25EC were evaluated for their fungitoxicity against theA. solaniat 100, 200,100, 600 and 800 ppm. Tall 25EC was the most effective fungicide againstAlternaria solanifollowed by Mancozeb 80WP. After screening the five tomato varieties againstA. 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 ofAllium sativumwas effective to controlAlternaria solaniat prescribed concentration. The highest PDI was found in BARI tomato-9 againstAlternaria solani.