One of 4 pages of the proposed Land Use Plan from the April 2015 update
Improving our communities together
2015 04 30 Land Use Plan – sheet 3
Until July, sap beetles are attracted to fresh tree wounds and can transmit the oak wilt fungus to a healthy oak tree during pruning. The heat of July-August is believed to suppress the beetles and reduce the risk of infection. Note that all trees are under the normal stress of summer, depending on soil moisture, and some are still in their growing season then. So if you haven’t completed pruning of oaks by now, it’s best to wait until fall.