VIBURNUM LEAF BEETLE FOUND IN WESTCHESTER COUNTY

By Jerry Giordano

Community Horticulture Educator, CCE- Westchester County

Cornell Cooperative Extension of Westchester County has received some bad news. Dr. Paul Weston, entomologist of woody ornamentals at Cornell University, reported to CCE horticulture staff that the highly destructive viburnum leaf beetle had been found in Westchester County. This is the first time this invasive pest has been found in the county, although it had appeared in Dutchess County in 2006 and has been previously detected in most other upstate New York State counties. An observant resident of Hastings-on-Hudson reported the find through the Viburnum Leaf Beetle Citizen Science web site; a collaboration between horticulturists, home gardeners and entomologists at Cornell. Digital photos sent by the observer offered unmistakable proof of identification, said Weston in an email to Rick Harper and Jerry Giordano of the CCE office in Valhalla. Weston continued, “I haven't heard ... yet... whether the infested plant (or others nearby) were recently planted; I'm doubtful the beetle could have moved that far so fast given that it's been known to be in Dutchess County for less than 2 years." Needless to say, its presence here, though expected, is still disturbing, as it signals a potentially devastating pest threat to many species of the much loved viburnum, particularly many of the native types now growing naturally in the Westchester landscape.

Viburnums vary in their susceptibility to the viburnum leaf beetle, from those that are categorized as "highly susceptible" to those that are nearly immune. European cranberrybush viburnum (Viburnum opulus), American cranberrybush viburnum (Viburnum opulus var. americana, previously known as Viburnum trilobum), and arrowood viburnum (Viburnum dentatum) are in the "highly susceptible" group. Koreanspice viburnum (Viburnum carlesii), doublefile viburnum (Viburnum plicatum f. tomentosum), and Siebold viburnum (Viburnum sieboldii) are among the most resistant. Other species have varying degrees of susceptibility to this beetle. It can kill highly susceptible types in the first 2 to 3 years after an infestation begins.

Weston’s research group has developed a number of management strategies for viburnum leaf beetle, which are detailed on the Viburnum Leaf Beetle Citizen Science website at www.hort.cornell.edu/vlb/ Although a variety of effective control measures have been identified, Weston is hoping to develop control without pesticides using biological methods. Gaylord Desurmont, a graduate student in

Dr. Weston’s lab, is

beginning preliminary research using tiny wasps from Europe that specifically target viburnum leaf beetle, but progress will likely be slow until additional funding can be secured. “The reality is that research usually progresses as fast as the amount of funding available will allow”, said Weston. This is perhaps a chance on the part of those willing to contribute additional funding to significantly alter the destructive progress of this pest. Those wishing to take part in funding research toward controlling this insect in an earth-friendly manner should contact Carol J. Burnett, Assistant Director of Alumni Affairs, 274 Roberts Hall, Ithaca, NY 14853. You may also telephone Carol at 607-255-7661 or email her at cjb30@cornell.edu. Contributions should be accompanied by a note designating that the funds are to be used for the support of viburnum leaf beetle research in the Cornell Department of Entomology under the guidance of Ann Hajek.

Follow-up of the discovery of viburnum leaf beetle in Westchester is planned by local CCE staff with assistance from Dr. Weston. In the meantime, please visit the Citizen Science website to familiarize yourself with details about this insect, its history in the Northeast, and possible management strategies. The more eyes looking for this "Little Brown Menace," as Weston has referred to it, the better!

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