Biocontrol of Alternaria alternata Causing Leaf Spot Disease on Faba Bean (Vicia faba L.) Using Some Trichoderma harzianum Isolates Under In vitro Condition

Faba bean is among common legume crops used as a fresh vegetable in Turkey.  Alternaria alternata is one of the main fungal diseases attacking faba bean in Turkey. Investigation of leaf spot disease of faba bean was carried out to find out suitable management strategies under laboratory condition. Five A. alternata ( A1, A2, A3, A4, and A5) and five  Trichoderma harzianum  isolates (T1, T2, T3, T4, and Tc) including control were arranged in complete randomized design factorial, forming a total of 25 treatments. Dual culture plate test revealed that the percentage growth inhibition of  A. alternata by T. harzianum  was in the range of 53.85 to 82.81 %. In addition,  Trichoderma  isolates (T2 and T3) were found the most effective with the highest antagonistic activity against  A. alternata  isolates fungal pathogen caused minimum length and width diameter of leaves lesions. The species of  Alternaria  and  Trichoderma  isolates were identified according to cultural characteristics and alignment analysis of ITS sequences in GenBank of NCBI. The results point out that T . harzianum  provides the use of high potential antagonists capable of controlling the leaf spot disease of faba bean plant.