Older oak trees have been plagued with health problems and are dying in large numbers throughout Maryland. Why? Both researchers and homeowners are asking the same question. The tree diagnostic laboratories have identified an assortment of diseases and pests on the dying trees. Yet no single, conclusive problem is killing them all. It remains a mystery. A few facts that everyone agrees on are these: We have never had so many mature oaks in our forests, so maybe this is the way they naturally decline. We experienced unusually wet summer weather in 2018 and 2019. Researchers believe this could have compromised the relationship between the mature oak roots and the fungus on which they depend for water absorption. As a homeowner, you can try to alleviate oak drought stress. If we experience a July/August drought, watering the area around the drip line of a tree can reduce stress. The objective would not be to stimulate growth with volumes of water, but instead to sustain the tree during the drought period. If your oak is in a lawn and you feed the turf once a year, that will suffice. Visit the Home and Garden Information Center website for a summary article.

Joyce Browning Horticulturist, Master Gardener Coordinator Video credit: Bethany Evans Longwood Gardens Professional Gardener Program Alumni; CPH