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5-21-2003 |
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SPRING DEFOLIATORS NUMEROUS ON WHITE OAKS THIS SEASON According to Agriculture Commissioner Gus R. Douglass, the West Virginia Department of Agriculture (WVDA) has been receiving reports of defoliation on white oak this spring. Specimens sent to the Pest Identification Laboratory indicate that a miscellaneous group of caterpillars are causing the defoliation. The predominant defoliators include the common oak moth and several inchworms, including spring cankerworm, fall cankerworm, linden looper and half-wing geometer. Contact with landowners, WV Division of Forestry personnel and West Virginia University Extension Service personnel places defoliation as occurring in Braxton, Gilmer, Ritchie, Wirt, Jackson, Kanawha, Putnam, Wayne and Mingo Counties. The heaviest defoliation has been reported in and near Cabwaylingo State Forest in Wayne County. Elsewhere, the defoliation has been reported as moderate to heavy. “During the attempt to collect specimens for identification purposes, it has become obvious that the worst of the defoliation is over,” stated WVDA Forest Entomologist Sherri Hutchinson. “Most of the caterpillars are beginning to drop to the ground to pupate.” It is not unusual for inchworms, or loopers, to show up in large numbers. These are native insects that periodically have high populations that may be triggered by stress, such as drought conditions. They are present in high numbers for 2-3 years and then collapse due to high corresponding numbers of predators and parasites. This spring, the looper defoliation is occurring along with a number of other miscellaneous oak-feeding caterpillars, which is making the defoliation very noticeable. The common oak moth, Phoberia atomaris, is also a native insect, nearly an inch long when mature, hairless, and generally dark brown and black in coloration. They have two rows of small, black triangles that occur down the length of the back of the caterpillar. This pest prefers white oak as a host. The loopers come in a variety of different colors, but they all have the typical tail-to-nose “measured” movement. They defoliate a larger variety of hardwood hosts such as maple, wild cherry, elms and hickories. While it is never good for a tree to be completely defoliated, early spring defoliation usually results in a second flush of leaves. If the trees were very healthy prior to the infestation, the majority of trees should recover. Trees previously stressed from weather, insect or disease problems will have a harder time maintaining their health. At the very least, it does mean that the trees will be starting off the season in a stressed state. If drought conditions or other stress factors occur later this year, some decline and/or mortality will result. If you would like to report defoliation on white oak in counties
not mentioned, please contact the WVDA, Plant Industries Division
at (304)-558-2212. Contact with landowners, WV Division of Forestry personnel and West Virginia University Extension Service personnel places defoliation as occurring in Braxton, Gilmer, Ritchie, Wirt, Jackson, Kanawha, Putnam, Wayne and Mingo Counties. The heaviest defoliation has been reported in and near Cabwaylingo State Forest in Wayne County. Elsewhere, the defoliation has been reported as moderate to heavy. “During the attempt to collect specimens for identification purposes, it has become obvious that the worst of the defoliation is over,” stated WVDA Forest Entomologist Sherri Hutchinson. “Most of the caterpillars are beginning to drop to the ground to pupate.” It is not unusual for inchworms, or loopers, to show up in large numbers. These are native insects that periodically have high populations that may be triggered by stress, such as drought conditions. They are present in high numbers for 2-3 years and then collapse due to high corresponding numbers of predators and parasites. This spring, the looper defoliation is occurring along with a number of other miscellaneous oak-feeding caterpillars, which is making the defoliation very noticeable. The common oak moth, Phoberia atomaris, is also a native insect, nearly an inch long when mature, hairless, and generally dark brown and black in coloration. They have two rows of small, black triangles that occur down the length of the back of the caterpillar. This pest prefers white oak as a host. The loopers come in a variety of different colors, but they all have the typical tail-to-nose “measured” movement. They defoliate a larger variety of hardwood hosts such as maple, wild cherry, elms, and hickories. While it is never good for a tree to be completely defoliated, early spring defoliation usually results in a second flush of leaves. If the trees were very healthy prior to the infestation, the majority of trees should recover. Trees previously stressed from weather, insect or disease problems will have a harder time maintaining their health. At the very least, it does mean that the trees will be starting off the season in a stressed state. If drought conditions or other stressors occur later this year, some decline and/or mortality will result. If you would like to report defoliation on white oak in counties
not mentioned, please contact the WVDA, Plant Industries Division
at (304)-558-2212. |
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