black knot control on young plum trees
I planted about 12 bare root euro plums in the spring of 2013. Several already have black knot. I got them from 4 different nurseries so I think the problem is mine, not any one nursery. There was two huge choke cherry trees next door cut down in the early summer, maybe they were the source and it spread when they fell. Anyway, I don't think I can properly prune several inches back from each knot and still have much tree left. I was thinking of trying the following: mix some powder copper bordeaux with some diluted white latex paint and painting over the whole area after I cut the individual knots out. I figure the diluted latex should hold the copper in place for several months, hopefully keeping any fungus inside the branch from forming on the outside and spreading. Any thoughts on wether this would be worth it, or should I just prune them back to a walking stick? I'm probably going to order black knot resistant Blue Byrd Plum, President Plum and a Kenmore in the spring, but I'd like as many of the trees I planted this year to make it as possible.