Almond trunk and branch canker diseases constitute a major cause of tree mortality in California. Numerous fungal pathogens have been associated with these canker diseases and pruning
wounds act as major
infection courts. Before this study, there were no products registered in California for the management of these diseases. In this study, fungicidal products including synthetic chemistries, biocontrols, paint, and a sealant were evaluated for preventing fungal pathogen
infection via pruning
wounds. In four field trials conducted over two dormant seasons, 16 pruning
wound treatments were tested using handheld spray applications against five almond canker pathogens, namely Botryosphaeria dothidea, Neofusicoccum parvum, Cytospora sorbicola, Ceratocystis destructans, and Eutypa lata. The fungicide
thiophanate-methyl (Topsin M; United
Phosphorus, Bandra West, Mumbai, India) provided 82% overall disease prevention against four fungal pathogens. The
biological control agent, Trichoderma atroviride SC1 (
Vintec; Bi-PA, Londerzeel, Belgium), tested at three application rates, resulted in 90 to 93% protection of pruning
wounds in field trials, and for individual pathogens ranged from 81 to 100% protection for the three rates. At the time of this publication,
Vintec is being considered for registration as a
biological control product for the prevention of almond canker diseases, while Topsin M is recommended to growers for the prevention of almond canker diseases. This research indicates that effective protection of pruning
wounds from
infection by almond canker pathogens can be achieved with a one-time spray application of
thiophanate-methyl or the biocontrol T. atroviride SC1 (recommended 2 g/liter) after pruning.