Efficacy of Trichoderma harzianum in the control of Phytophthora infestans and its growth-promoting effect on two potato varieties

Abstract

Abstract Phytophthora infestans significantly affects potato crops, reason why farmers apply chemical fungicides as a quick and economical solution. However, the continuous, massive, and indiscriminate use of these products in the long term will have a negative impact on the environment and human health. Therefore, the use of dual-action bioagents has the potential to control the phytopathogen and increase sustainable potato yields. The objective of this study was to find a sustainable solution to minimize the use of chemical fungicides by combining improved potato varieties and different doses of Trichoderma harzianum. The field experiment was conducted using a complete randomized block design with a factorial arrangement, the factors of which were: varieties (commercial variety Yungay and improved variety CIP 302295.32), fungicides (Trichoderma harzianum and chemical fungicides such as metalaxyl+mancozeb) and doses (low, medium and high) in two production seasons. The results showed that high doses of chemical fungicides showed greater efficacy in controlling late blight in the improved variety CIP 302295.32. In contrast, the application of T. harzianum in vitro inhibits the mycelial growth of Phytophthora infestans, while in field conditions at medium and high doses of the bioagent in the improved variety CIP 302295.32, it does not outperform chemical control in both production seasons. This difference in control is due to field climatic conditions, which favour the development of the oomycete, making it more aggressive and virulent. However, the application of medium and high doses of T. harzianum in the improved variety significantly exceeded the chemical control in terms of height, number and weight of commercial tubers per plant and commercial yield of potatoes in both seasons. Therefore, the selection of the improved variety CIP302295.32 with the application of 1 kg ha-1 (concentration of 5 x 1012 of viable spores) of T. harzianum will be a sustainable solution for the control of late blight and good yield of potato.