Delayed pruning: Prune late in the dormant season (February or later, before budbreak) by hand, when both pathogen inoculum and wound susceptibility are lower, hence minimizing the risk of infection compared to December and January.
Hand-painted TopsinM: Topsin is a fungicide that provides a protective barrier on pruning wounds against infection by the spores of trunk pathogens. After pruning and before rain, the latter of which induces spore production, liberation and dispersal, apply Topsin by hand with a paintbrush or sponge to cover pruning wounds.1
Double pruning: Prune early in the dormant season (December or January) with a mechanical-pruning machine; partially prune canes to a length of approx. 0.4 m. Prune again late in the dormant season (February or later) by hand to two-bud spurs, to remove potentially infected canes.
For details on how to adopt these practices, please see the management guidelines at the SCRI Trunk Disease Project website.
1Protectants registered for hand application during the dormant season in California are Thiophanate-methyl (Topsin M WSB; United Phosphorus, Inc., King of Prussia, Pennsylvania), Boric acid (Tech-Gro B-Lock; Nutrient Technologies, Inc., Dinuba, California), and VitiSeal (VitiSeal International LLC, San Diego, California). Topsin is also registered for spray application.