Opportunistic pests take advantage of drought-weakened trees

 

HoustonTreeDamage
Photo courtesy of Houston Chronicle.

This story ran in the Houston Chronicle and features Davey Tree expert Jack Swayze talking about insects and diseases attacking the local trees.

Posted: 10/5/12

By Kathy Huber, garden editor

Although rains have eased the 2011 drought, opportunistic pests are taking advantage of weakened trees.

Bark beetles are having a field day among pines, and fungal diseases such as ganoderma and hypoxylon are pestering stressed oaks and other hardwoods.

Cases of ganoderma have probably doubled this year, says Jack Swayze of Davey Tree Expert Co. Once you see the shelflike fungi around a tree's base, internal decay is in the works. Call an arborist. While there is no cure, it's sometimes possible to extend a tree's life with good culture, including deep watering, proper fertilization and pruning. Compost and mulch also are beneficial, but don't pile them against the trunk.

Hypoxylon canker also is worse after a drought, says Kenneth Grayson of Fosters Tree Service.

"I'm seeing it all over town, especially in oaks, but also in maples and sycamores."

Branch die-back is one symptom of hypoxylon. Foliage on diseased limbs turns yellow and dries. The disease spreads from branch to branch until the tree dies, a process that may take one or more years. In the late stages of the disease, bark will slough to reveal powdery spores.

The only way to control hypoxylon is maintaining tree health and preventing bark wounds and root injury. Deep watering, proper fertilization and pruning are also crucial.

kathy.huber@chron.com

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