Evaluation of shelf life of biocontrol agent Trichoderma isolate T13 with different formulations

Abstract

Trichoderma isolate T13 has been identified as a potential biocontrol agent against the Panama wilt pathogen Fusarium oxysporum f. sp. cubense and it can be produced in mass quantities in-vitro. However better formulation is required for field applications. Therefore, here we report the evaluation of different formulations of Trichoderma isolate T13 in relation to its shelf life. As carrier materials, Talcum powder and Lignite were used in different ratios as follows (t1=0:50, t2=1:4, t3=2:3, t4=1:1, t5=3:2, t6=4:1, t7=50:0) and 10 mL of concentrated conidia suspension (6.16«109conidia/mL) of T13 was added to each treatment for the preparation of formulations. The best ratio was selected by assessing colony forming units (cfu/g) of Trichoderma T13 culturing in Trichoderma selective media at every 4 weeks intervals after inoculating into the sterilized soil. It has been revealed that 4 weeks after inoculation of soil, T13 population was significantly increased in all treatments (p<0.05) except t6 and t7 compared to T13 population at day zero. At 8th week of the post-inoculation, cfu/g of t2 significantly increased (p <0.05) while in other treatments’ cfu/g was increased but not significant compared with 4 weeks of the post inoculation. At 12th week of the post inoculation, fecundity (cfu/g) of t2 significantly increased (p <0.05) while cfu/g of t3 and t4 was insignificantly decreased. At the same time, viability of T13 in t1, t5, t6 and t7 was diminished significantly (cfu/g). However, cfu/g of t2 was started to reduce after 16 weeks of the post-inoculation and the t1, t3, t5, t6 and t7 showed decreasing trend with the time. According to the results, during 20 weeks from post-inoculation, formulation t2, showed significant conidia viability of Trichoderma isolate T13. Therefore, it can be concluded that, Talcum; Lignite 1:4 would be the best ratio for the formulation of T13 conidia for field application.