Fungal canker pathogens of almond initiate
infection in trees primarily through pruning
wounds.
Biological control agents (BCAs) have the potential to provide long-term protection of pruning
wounds by colonizing the
wound surfaces and underlying tissues. Laboratory and field tests were performed to assess the efficacy of various commercial and experimental BCAs as
wound protectants against almond canker pathogens. Four Trichoderma-based BCAs were evaluated using detached almond stems in the laboratory against the canker pathogens Cytospora plurivora, Eutypa lata, Neofusicoccum parvum, and Neoscytalidium dimidiatum. Results indicated that Trichoderma atroviride SC1 and T. paratroviride RTFT014 significantly reduced
infections by all four pathogens. The abilities of these four BCAs to protect almond pruning
wounds against E. lata and N. parvum were further evaluated in field trials using two almond cultivars and during two consecutive years. Both T. atroviride SC1 and T. paratroviride RTFT014 protected almond pruning
wounds against E. lata and N. parvum as efficiently as
thiophanate-methyl, the recommended fungicide for treatment of almond pruning
wounds. Comparisons of different application timings of BCA in relation to pathogen inoculation revealed a significant improvement in
wound protection when inoculations were conducted 7 days versus 24 h post-BCA application for N. parvum, but not for E. lata. T. atroviride SC1 and T. paratroviride RTFT014 are promising candidates for the preventive protection of almond pruning
wounds and for inclusion in integrated pest management programs and organic almond production systems.