Effect of Different Liquid Carriers On the Shelf-life and Antifungal Effectiveness of Trichoderma harzianum

The negative effects of plant protection chemicals on the environment and human health have led scientists to research alternative control methods. Fungi, especially Trichoderma have an important place in biological control, one of the most common alternative methods. Licensed as an agricultural product, it has been effectively used in agricultural lands. This study aimed to evaluate long-lasting carriers of the ET 4 and ET 14 Trichoderma harzianum isolates, proven effective against different pathogens in previous studies, to allow licensing for their commercial and mass production in the industry. The efficacy of ET 4 and ET 14 isolates against Alternaria solani (isolate ET 66) was initially confirmed by testing in vitro and in vivo conditions. Then, spores of the fungus isolate developed on potato dextrose agar (PDA) were transferred to five different liquid media (soybean oil, neem oil, canola oil, paraffin oil, and glycerine) prepared as the carrier formulations. They were kept at room (22 ℃) and refrigerator (+4 ℃) temperatures for 10 months. The viability tests of the bioagent fungus were performed by sowing into PDA from the monthly samples taken from the formulations. In addition, at the end of the tenth month, the efficacy of the bioagents was tested against the pathogenic fungus in vitro and in vivo conditions. Even though the most successful carrier was neem oil with a very intense bioagent development, the bioagent maintained its viability in all carriers even at the end of the 10th month, with percent inhibition rates varying between 37.85% and 52.33% in vitro and between 14.26% and 3.95% in vivo conditions. It was concluded that paraffin, glycerin, and especially neem oil were good carriers for the T. harzianum bioagent, that the shelf life could be extended even more with further studies, and that it could be licensed as a biopesticide after toxicological and ecotoxicological evaluations.