Campus & Beyond

Alumni Ag Experts Help Protect NY’s Poinsettia Industry

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Editor’s note: This story was adapted from a feature in the Cornell Chronicle.

By Caitlin Hayes

Last summer, Mark Van Bourgondien, co-owner of CJ Van Bourgondien Wholesale Greenhouses on Long Island, noticed white flecks and slight discoloration on a few of his young poinsettias. He quickly found the culprit: tiny white Lewis mites, which he and others in the industry had dealt with before. But this time, the usual control, a miticide, didn’t work.

Van Bourgondien called Cornell’s Long Island Horticultural Research and Extension Center (LIHREC)—his go-to when problems arise.

Dan Gilrein, MPS ’82, associate agriculture program director and entomology specialist for Cornell Cooperative Extension of Suffolk County, collected samples from Van Bourgondien and others in the region facing the same problem.

Back at LIHREC’s greenhouse, he confirmed the mites’ resistance and found an alternative treatment that could address the problem.

Integrated Pest Management's Elise Lobdell inspects a poinsettia.

“We’ve been able to manage it with Dan’s help,” says Van Bourgondien, whose family has been in the greenhouse business since 1916.

Lewis mites are just one of many potential threats and challenges to growing poinsettias, the colorful ornamental plant that is ubiquitous in holiday displays.

The plants require careful calibration of the greenhouse environment—low humidity with moderate temperatures—and are susceptible to multiple types of root rot, poinsettia mosaic virus, foliar fungal diseases called poinsettia scab, powdery mildew and botrytis blight, bacterial leaf spots, and infestations of different species of white flies and mites.

The plants require careful calibration of the greenhouse environment—low humidity with moderate temperatures.

Many of these threats are introduced from cuttings shipped from overseas and show up at various stages of a long season, with ample time for problems to arise; growers plant in early summer and need the crop in peak condition for an extremely narrow window of sales in late November and early December.

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“There’s a real art to growing poinsettias, and the people who are doing it have often been doing it for generations,” says Margery Daughtrey, PhD ’23, senior extension associate and plant pathologist in the School of Integrative Plant Science in CALS. “They really care about the crop and do everything they can to protect it.”

There’s a real art to growing poinsettias, and the people who are doing it have often been doing it for generations. They really care about the crop and do everything they can to protect it.
Margery Daughtrey, PhD ’23, senior extension associate and CALS plant pathologist

Profit margins for poinsettias are thin, and their production in New York has declined over the last three decades. But growing poinsettias provides year-round work for the 120 to 130 full-time employees of Emma’s Garden Growers, a Long Island plant wholesaler, and allows the business to maintain a connection to its customers, as well as boosting income going into the new year.

“A lot of people depend on this business—they want to be employed year-round—so that means: poinsettias,” says co-owner (and father of three Cornell alums) Eric Keil, whose family has been in the horticulture business on Long Island for four generations.

A “Candy Cane” poinsettia — A Candy Cane poinsettia.

“The services at LIHREC are absolutely essential to our industry; I don’t know how growers in other states really get by without this kind of support.”

When further investigation is needed, the LIHREC team collaborates with New York State Integrated Pest Management in CALS and researchers on Ithaca’s campus.

In the case of this season’s Lewis mites, Gilrein is continuing work with on-campus partners to understand the underlying mechanism of the mites’ resistance, how it could affect future seasons and other crops, and what optimal controls could be used.

“We feel there are some newer controls that we haven’t tried,” Gilrein says, “so we’re engaged in seeing how those perform and whether or not a biological control could work or could make sense.”

Solving a problem—or finding a culprit and ways to outwit it—is satisfying, Daughtrey says. And the stunning beauty of the poinsettia crop can also be its own reward.

“When the plants are in the greenhouse, and they’re lined up perfectly in their rows, all the same height and in full bloom, with all variations from white to peppermint to deep red—it’s just awfully beautiful,” Daughtrey says. “Especially on a snowy day, to walk in and see all that color; it’s marvelous.”

(All photos provided.)

Published December 13, 2024