Golf Course Management

OCT 2014

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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70 GOLF COURSE MANAGEMENT 10.14 ered through DNA analysis that the hemlock woolly adelgid was native to the Pacifc North - west. According to McDonald, whose ento- mological focus is biological control of insects, "This changed everything." "It meant both the adelgid and L. nigrinus are native to our country, and we could begin collecting L. nigrinus and bringing it back to the East Coast to use as a predator in HWA- infested regions," he says. He explained that in the Pacifc North - west, hemlock woolly adelgid is not a problem for hemlocks because it is kept in check by a natural system of insects. It has become a pest on the East Coast because no natural preda - tors are present in the environment. Once the adelgid infestation spreads to 45 percent of a tree's needles, the tree begins to decline, mak - ing this the ecological threshold for taking ac- tion. "We're attempting to recreate that balance here by introducing HWA's natural predators, and we've identifed L. nigrinus as one of the best," says McDonald. "When present, this beetle lowers the infestation rate of HWA on hemlocks well below the threshold, enabling them to regrow normally." Laricobius nigrinus is a tiny black beetle that McDonald describes as an "oddball" be - cause it's active in the winter, the inverse of most insects, which complete their life cycle in the spring and summer then go dormant in the fall. "Both L. nigrinus and HWA are unusual in this regard," he says. "The adelgid is in a resting stage in the summer, and around mid- October, when temperatures begin to cool, it comes out of its dormancy." That's when L. nigrinus arrives on the scene. It feeds on all life stages of the adelgid throughout the late fall and winter and into early May. It dramatically lowers the infesta - tion rate of the adelgid, allowing trees to re- grow and thrive even in the continued pres- ence of the pest. This makes L. nigrinus a perfect match for controlling the adelgid. In 2008, McDonald and Gerdon received support from the Grandfather G&CC board of directors to collect L. nigrinus beetles in the Pacifc Northwest for introduction to their property. Over the past six years, they have collected about 14,000 L. nigrinus beetles for release at more than 40 sites on Grandfather G&CC grounds, making the club the largest L. nigrinus release site on the East Coast. A second hemlock woolly adelgid preda - tor, Scymnus coniferarum, a small black and gold ladybeetle, was discovered in the Pacifc "We're attempting to recreate that balance here by introducing HWA's natural predators, and we've identifed L. nigrinus as one of the best," — Richard McDonald Hemlocks play a critical role in conserving mountain ecosystems; their branches supply much-needed shade to cool streams that are home to trout, other native fsh and a variety of aquatic life forms.

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