by Elizabeth A. Tomlin
“An accurate diagnosis is key to solving problems on tree farms,” emphasized Brian Eshenaur, Plant Diagnostician, Plant Pathology, Senior Extension Associate for the New York State Integrated Pest Management program with Cornell University.
Eshenaur, along with Dr. Elizabeth Lamb, New York State Integrated Pest Management Program/Horticultural Specialist, Cornell, and Lily Calderwood, Commercial Horticulture Educator, Cornell, presented an updated program on Hemlock Wooly Adelgid, Balsam Woolly Adelgid and other Christmas tree diseases at Goderie’s Tree Farm/BTF-Wholesale’s 10th annual Open House in Fulton County, NY.
Lamb described Hemlock Woolly Adelgid (HWA) as an aphid-like invasive insect native to Asia that is now presenting a serious threat to forest and ornamental hemlock trees in the Northeast. It is recognizable by the white “woolly” masses of wax that are about half the size of a cotton swab. They are produced by females in late winter and are visible at the base of hemlock needles throughout the year, even after the adults have died.
“They look like they are ‘flocked’,” Lamb commented.
The insect that targets Eastern and Carolina hemlock trees has been reported to have severely damaged some sites with losses of up to 90 percent of saplings and 50 to 69 percent of total stand density.
HWA is spread by wind, birds, humans or other animals and reproduce twice yearly. Lamb noted that no males are produced; all are female and reproduce asexually.
The disease is active during the winter, allowing it to avoid summer predators and allowing it to sap hemlock’s increased winter energy intake.
The tiny black insect lives and feeds on the hemlock. Once eggs hatch, nymphs move to new needles and attach themselves to the base, feeding from starch reserves and nutrients, causing needles to dry up and fall off and preventing growth. Hemlocks with the disease may live up to 20 years before death.
Cutting and moving the tree can cause the spread of the insect to other trees.
“There is no documentation of spruce infestation in New York,” Lamb remarked.
Report any discovery of HWA to DEC’s Forest Pest Management Information Line at 1-866-640-0652.
Balsam Woolly Adelgid (BWA) targets all species of fir — especially Fraser, balsam and Canaan Fir.
“This one will kill the tree,” reported Dr. Lamb. “Christmas tree growers are seriously at risk from this insect and disease.”
Lamb reported that BWA is also reproduced asexually by females. The disease causes “gouting” and unsightly bulbous swellings.
Nymphs (aka crawlers) are spread over short distances by wind or animals movement. They attach to the bark of the tree, where they insert their piercing, straw-like mouth into the bark, sucking out the sap. As they feed they produce a woolly covering of wax. They remain sedentary until they mature into adults, laying eggs under the wax. Depending on latitude and elevation, these insects may produce three generations per year, even overwintering as immature nymphs.
“It doesn’t take long to get a large population,” said Lamb.
Because the Balsam Woolly Adelgids are tiny and difficult to see, the white woolly wax substance is one key to discovering them. Flat top appearance or a weak, slanted terminal; swollen, gouted twigs that drop their needles; dead shoots or branches and wilted appearance of shoots are common symptoms to scout for.
Eshenaur advises that these trees need to be handled carefully to discourage spreading of the insect to nearby trees. “Do not drag this tree,” Eshenaur cautioned. “That will cause spreading.”
Bagging the tree is strongly advised and burning it should be considered.
The Cornell IPM team strongly advised monitoring nursery stock, which is potentially a host for these invasive insects. “Buy clean nursery stock. Scout plant material as it arrives with a hand lens.”
Another way they are moved is through transporting firewood from other localities, as they may be harbored in the bark of the wood. Practice prevention.
For more information on this serious disease go to
Beneficial insects are being investigated for controlling these diseases.
Lamb reported that due to pollinator issues, there are potential possibilities for “pollinator habitats.”
“Christmas tree growers are good stewards of the land,” commented Lamb. “There is so much interest now in pollinators.”
Folks interested in the pollinator habitat program may contact for more information.
Due to the new diseases related to ticks, the IPM team advises growers to “keep the grass down” in tree lots, especially where folks are coming in to cut trees themselves. “There is a renewed interest in people cutting their own Christmas trees,” said Lamb.
Eshenaur spoke to attendees about root rot in their nursery stock. “There are a couple important root rot diseases that can be a problem,” Eshenaur said. “In order to take action and head off future problems it is important to know which one you have.”
Lamb emphasizes the importance of “face to face interaction and the development of a relationship between Extension and growers” to help make all of their programs relevant. Contact Dr. Lamb at
“This was the 10th year for BTF Wholesale/Goderie’s Tree Farm hosting an Open House and it was one of the best turnouts we’ve had since the first one, which was a joint venture with Christmas Tree Farmers Association of New York,” remarked Peter Goderie. “There were 65 attendees from 38 farms, some traveled from as far away as Buffalo, NJ and Painted Post, NY. But the majority were from the Capital District, Adirondacks and Syracuse/Oswego area.”
Goderie’s also had wreath, kissing ball and garland making classes and demonstrations, along with bow making and decorating during their Open House event.
“Ned Chapman from Dutch Church Farm discussed his recent visit to the Michigan Tree Farmers summer meeting and a number of research projects involving Christmas Tree production that are going on, as well as the results of a focus group study on tree consumers,” reported Goderie. “Ned also talked about his Christmas Tree plugs and the direction he is heading, having them available for spring plantings and the potential use of tissue culture instead of seed for production.”
Goderie said that attendees discussed where the “check-off” program was heading and that the group seemed to be mostly against the check-off program.
For more information go to