If oaks are wounded or must be pruned during these months, apply wound dressing to mask the odor of freshly cut wood so the beetles that spread oak wilt will not be attracted to the trees. To avoid increased likelihood of stem cankers , prune honeylocusts when they are still dormant in late winter. If they must be pruned in summer, avoid rainy or humid weather conditions. Spring or summer pruning increases chances for infection and spread of the bacterial disease fireblight. Autumn or early winter pruning is more likely to result in drying and die-back at pruning sites.
Some trees have free-flowing sap that bleeds after late winter or early spring pruning.
Though this bleeding causes little harm, it may still be a source of concern. To prevent bleeding, you could prune the following trees after their leaves are fully expanded in late spring or early summer. Plants with marginally hardy stems such as clematis and shrub roses should be pruned back to live wood. After the initial pruning at planting, hedges need to be pruned often. Once the hedge reaches the desired height, prune new growth back whenever it grows another 6 to 8 inches.