Biocontrol de Alternaria solani y A. alternata en el cultivo de papa con Trichoderma harzianum

Abstract

Chemical control is the main management strategy for potato early blight, caused by Alternaria solani and A. alternata. The aim was to evaluate the efficacy of biocontrol of Trichoderma harzianum against A. alternata and A. solani and to understand their mechanisms of action. The inhibition of T. harzianum on A. solani and A. alternata was evaluated by means of dual cultures growing on the same plate or on facing plates, measuring the radial growth of the colonies. Greenhouse experiments were conducted in a randomized complete plot design with 12 replicates. Potato plants were inoculated until run-off with conidial suspension between 70-84 days after crop planting (DAP). Treatments: T1=inoculated control, T2=T. harzianum application at 60 and 75DAP, T3=T. harzianum applied weekly from 45DAP, T4=boscalid+piraclostrobin application at 60 and 75DAP. Leaf incidence was evaluated and the area under the disease progress curve (AUDPC) was calculated. Colonies of Alternaria spp. growing with T. harzianum had a smaller diameter, lower growth rate and darker color compared to the controls. In the greenhouse, differences in incidence and AUCPE were observed between the treatments with T. harzianum with respect to the control, being lower in some determinations. The AUDPC was similar in T3 and T4 in A. solani, while T4 was similar to T2 in A. alternata. This results are promissory to protection of potato crop from A. solani y A. alternate with T. harzianum.