Modes of action and inhibitory activity of Trichoderma species on potato and tomato pathogenic Phytophthora infestans: A review

Late blight, caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of potatoes and tomatoes, resulting in low yields and economic losses for farmers. Trichoderma spp. are known for their antagonistic abilities against a wide range of pathogens, including P. infestans. This review provides an overview of the current knowledge on Trichoderma spp., by (1) classifying the diversity of modes of action of Trichoderma species and (2) assessing the antagonistic ability of several species and strains of Trichoderma spp. against P. infestans in dual culture, through a meta-analysis. We found that many species of Trichoderma spp. have a double action against P. infestans, both (1) direct on the plant pathogen by emitting enzymes and volatile organic compounds and (2) plant-mediated by enhancing the host plant's defence potential. The meta-analysis showed that direct Trichoderma antagonistic ability against P. infestans is species and strain dependant. Among the most effective species, T. asperellum stands out with a mycelial inhibition potential of up to 90% for some strains. These findings were used to build a decision-making system, that accounts for Trichoderma-plant-Phytophthora interactions, pedoclimate, and strategies of Trichoderma spp. application on crops. The paper provides new insights into the management of P. infestans on potato and tomato crops and highlights promising biocontrol or fungicide mixtures, including several Trichoderma spp. and little-known species with promising regulatory effects on P. infestans.