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Healthy Trees Resist Disease

Prevention is the surest cure

     Several Bay Weekly readers have contacted me lately concerning smelly fluid oozing from the trunks of older trees. One noticed it after seeing a large cluster of flies covering about a square foot of bark at the base of an oak tree.
     What they’re seeing is wet wood, or slime flux, a tree disease that afflicts older trees, especially after the tree has been struck by lightning or suffered wind damage. Symptoms are most severe if the trees are under stress from growing in soils that are heavily compacted, poorly drained or deficient in nutrients.
     Symptoms often do not appear until several years after some form of physical damage. Early visible symptoms are a dark-wet patch of bark that elongates over time. There may also be a strong foul odor, especially on elm trees.
     The early method of treatment was to use an ice pick to identify the area of spongy wood, then drill a three-quarter-inch hole at the lower end of the spongy wood and insert a piece of copper pipe into the hole. The purpose of the pipe was to direct the fluid drip onto the ground rather than the bark. Over the years, I never saw any benefits from this method.
     In the early 1970s, Dr. Alex Shigo of the University of New Hampshire initiated a study. He reported that the best method of control was to make the tree healthy again. If poor drainage was the cause, improve the drainage by either preventing water from pooling around the tree or installing drain tiles. If the soil from the tree’s drip line to the trunk was compacted, aerate the soil. If soil test results indicated nutrient deficiencies, apply fertilizer. His studies indicated that healthy trees never had the problem, and that by improving the health of a tree, the problem disappeared.
     When we moved to Upakrik Farm in Deale in 1990, one of the large oaks in our lawn had a mild case of wet wood. In 1992, I vertically mulched the trees using LeafGro. I have vertically mulched the trees every seven to eight years since. The wet wood on my oak tree disappeared by the fall of 1992 and has never reappeared. However, the symptoms are still visible in an elongated section of bark that is bleached out where the fluid once flowed.
     I recently saw a landscape where a well-known tree service was air-spading around an old oak tree, blasting the soil away from the roots. The turf had been removed, and dirt was flying all over the place. The next step would be to add new soil blended with compost and fertilizer before laying new turf. I was told that the company had developed this method of saving old trees.
     Vertical mulching would have been much less damaging and cheaper, too.
     As it would have been for a friend who paid $500 to have compost tea pumped into the ground around his tree. The company placed a five-gallon bucket full of LeafGro into a filter bag and suspended the bag in 100 gallons of water. This compost tea was injected into the ground via a three-foot needle.
I laughed at that.
     Keep your trees healthy by keeping them well nourished in well-drained, uncompacted soil. Fertilizing the lawn beneath the branches does not guarantee that the roots are being fed.