by Sharon Morrisey, Milwaukee County consumer horticulture agent
As a general rule, pruning of woody landscape plants should not be done in midsummer. The one exception is water sprouts on fruit trees, particularly apples and crabapples. Both are in the genus Malus and have a greater tendency to produce water sprouts than most other genera. Water sprouts form in response to pruning out large, diameter branches.
It has been shown that if the removal of water sprouts is delayed until late July or early August, fewer new water sprouts will form. If pruned out in early spring when all other pruning is being done, more water sprouts will be stimulated and a vicious cycle begun.
Water sprouts are branches that grow straight up from a larger-diameter branch. They grow very quickly and arise from latent buds buried deep inside the larger branch. The sprouts push through the outer layers of wood and bark.
As they grow taller and thicker, they become top heavy. Since they have no real connection of the branch, summer and winter storms can blow them over, and in the process, break the branch they are growing on. These sprouts also look awkward and out of place.
To avoid having to prune out large branches, begin developing the structure of trees when they are young so you remove only small branches.