Enhancement of the biocontrol mechanisms of Trichoderma longibrachiatum combined with different supplements for controlling Sclerotinia sclerotiorum in Phaseolus vulgaris.

The fungus Sclerotinia sclerotiorum is a highly destructive soil-borne pathogen that causes a significant threat to common bean production regions worldwide. In this study, Trichoderma longibrachiatum was mixed separately with various supplements to promote its efficiency in controlling S. sclerotiorum in common beans. The results indicated that the filtrate of T. longibrachiatum blended with potassium tartrate was the most efficient inhibitor of the growth and sclerotia formation of the pathogen. The same mixture also caused enormous morphological deterioration to the mycelia and sclerotia as observed using scanning electron microscopy. The FTIR spectra showed remarkable changes in vibrations related to the functional groups of all treatments. SDS-PAGE fingerprints and SCoT markers were used to determine the differences between treatments. In the greenhouse experiment, the rate of surviving plants in the treatment of T. longibrachiatum combined with potassium tartrate, thiamine, niacin, and a mixture of micronutrients was much higher than in the control groups after 30 days. The treatment of T. longibrachiatum mixed with potassium tartrate resulted in the highest levels of total phenolics, polyphenoloxidase activity, and peroxidase activity in the leaves of common beans. Furthermore, the same treatment displayed a higher number of surviving common bean plants under field conditions after 30, 45, and 60 days in soil naturally infested with the pathogen while also improving plant growth parameters. This study provides valuable insights into the effective biocontrol of S. sclerotiorum using T. longibrachiatum, in combination with various supplements, and highlights the potential for successful application of this strategy in common beans.