Thus, a severe pruning of last year's growth on plums is not likely to affect this season's crop to the extent that it would peaches. Over-pruning causes excessive vegetative growth and reduces fruit production. Plum varieties differ significantly in growth habit. Thus, pruning will have to be modified based on growth habit of the variety you have. You can do summer pruning in August or September.
Nothing needs to be put on the pruning cuts.
Research has shown that wound paints do nothing to help the healing process. The most important thing to remember is to make good smooth cuts by having a good pruning saw, lopping shears, or hand pruners. Sid Mullis is director of the University of Georgia Extension Service office for Richmond County. Contact the webmasters.