Berta Onland wrote: A number of years ago, I finally had to cut (after several attempts at pruning out) my only plum tree down because of black knot. It persists around the property mostly on what I believe to be wild cherry trees and some chokecherry bushes. I want to grow plums though so any tips?
I'm not familiar with black knot, but I found what seems to be a useful reference
here. Apparently some varieties of plums are more susceptable than others:
Japanese plums are said to be less susceptible than American varieties. A number of plums, including President, Early Italian, Santa Rosa and Shiro carry varying degrees of resistance to the fungus. Susceptibility varies depending on the climate zones. Varieties that are susceptible in humid southern climates may be less so in dryer or cooler ones.
So you could try one of those varieties perhaps. Also because the spores are active in spring, you can reduce the incidence of infection by spraying neem oil from before bud break every 7 to 10 days till the weather gets drier.
They also suggest inspection for the first signs of infection and pruning especially in winter:
Look for cracks, discoloration, swelling, or other first signs of infection. Check carefully around twig and leaf axils.
disinfecting the pruning saw/knife in between cuts to avoid spreading the infection.
Planting upwind of possible trees that harbour the disease may also help. Good luck.