Cornell: Leek moth threatens Northern New York’s onion farms

The Cornell Cooperative Extension (CCE) associations of Northern New York are asking farmers to report any findings of leek moth, a pest that prefers onions, garlic, chives, shallots, leeks, and other similar crops.

Cornell University and CCE researchers — working with a Northern New York Agricultural Development Program grant to trap the pest to identify its range — say that if the leek moth takes hold in the major onion-production areas of New York, the economic damage could be significant to the $54 million industry.

“The Northern New York Agricultural Development Program (NNYADP) grant will help us determine where leek moth is, how fast it is spreading, and will help growers properly time control treatments,” Cornell Cooperative Extension of Clinton County Executive Director Amy Ivy, a horticulture specialist, said in a news release.

Masanori Seto, with the Cornell University Department of Entomology at the New York State Agricultural Experiment Station in Geneva, says the current distribution of leek moth includes Clinton, Essex, Jefferson, and St. Lawrence counties as well as one county in Vermont.

A nocturnal pest, the leek-moth adult is rarely seen unless trapped, according to researchers. Leek moth was first spotted in the U.S. in Northern New York in 2009 in garlic and onions in a home garden in Plattsburgh (Clinton County.) The pest was identified in St. Lawrence County, near Canton, in 2010. Commercial growers in Essex and Jefferson counties reported finding leek moth in their fields in 2012, the news release said.

The adult leek moth is speckled brown, black and white with a white spot halfway down its outer pair of wings, researchers say. The adult survives the winters in northern New York and becomes active in the spring. The larva feeds mainly on plant leaves, from inside. It sometimes bores downward into the plant bulb and leaves feeding damage, according to researchers.

Leek-moth damage stunts plant growth, introduces rot, reduces the storage life of onions and garlic, and hurts the marketability of the crops, according to the news release. Cornell University entomologist A. M. Shelton is evaluating insecticidal treatments in his Ithaca campus lab. He is developing a growing day-degree model to help growers target the right times to apply insecticides to crops, the release noted.

As part of the NNYADP-funded grant, Shelton is also investigating ways to use biological-control agents effective in controlling leek moth.

“Eradication is not realistic, so we are learning to properly time treatments to reduce leek moth populations and the associated crop damage,” Ivy said in the release.

Two insecticidal products are currently approved for use on organic crops and three for use in conventional farming, the release noted.

Ivy encourages growers to implement the cultural practices currently available to growers to prevent leek-moth infestation. Those practices, the release explained, include the use of row covers right after planting to prevent adults from laying eggs on host crops, crop rotation, delayed planting, good field and harvest hygiene, scouting and destruction of leek moth pupae or larvae, and early harvesting before the final seasonal flight occurs.

The farmer-driven Northern New York Agricultural Development Program says it funds on-farm research, technical assistance, and outreach projects to support the productivity and economic viability of farms across New York state’s six northernmost counties.

Contact Rombel at arombel@cnybj.com