This Week in the Garden: Your Questions Answered, Week of April 20
Question:
I’ve heard I shouldn’t prune my oak trees this time of year – why?
Answer:
Try to avoid pruning any oaks from now until at least July 15. The reason is that we are currently in a HIGH RISK period for OAK WILT, from April 15 to July 15. Oak wilt is a deadly disease that affects oak trees. Oak wilt is caused by a fungus which survives in infected living oaks and in oaks recently killed by the disease. The fungus can also survive in firewood harvested from an infected tree.
Sap beetles are attracted to mats of the oak wilt fungus in infected trees, pick up spores of the fungus on their bodies, then carry spores to healthy trees. These beetles are attracted to trees that have been recently wounded by wind or storm damage, or by pruning. And these beetles can find these wounded trees within minutes of the injury.
Pruning most woody trees and shrubs should be done during the winter when diseases and pests are less active. But understandably, you might have to deal with storm damage or unexpected pruning. While we don’t typically recommend applying any sort of pruning paint, IF you are pruning during this time of year, then you should immediately apply a pruning paint over the wound.
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