Alfalfa growers in Madrid and elsewhere in North Country raising Nematodes to fight invasive beetle
Sunday, November 28, 2010 - 7:45 am

Twenty-one years of research and field testing have paid off for alfalfa growers in Madrid and elsewhere in the North Country.

Cornell University interns are introducing growers across Northern New York to an inexpensive farmer-friendly way to get rid of the invasive alfalfa snout beetle (ASB).

They are teaching farmers how to rear and apply native nematodes that appear to be an enduring solution ASB problem.

“Raising the nematodes on the farm was a great project for my 14-year-old daughter and we have seen positive results that benefited our farm and helped us help a neighbor who lost his alfalfa to the beetle and needed to buy some in,” said Lou Ann King of Mapleview Dairy in Madrid.

The 30-page “Rearing and Applying Nematodes to Control Alfalfa Snout Beetle” manual that condenses the Cornell research that led to an on-farm biocontrol method to control Otiorhychus ligustici is now online at www.nnyagdev.org.

More than 13 percent or 500,000 acres of the New York’s agricultural land has been infested by ASB that can destroy entire fields in one year.

The flightless insect likely arrived in the Port of Oswego in the ballast of sailing ships in the 19th century.

It has walked and hitchhiked from Oswego County to St. Lawrence County and seven other counties -- Cayuga, Clinton, Essex, Franklin, Jefferson, Lewis and Wayne – as well as southeastern Ontario, Canada.

Long-term funding for alfalfa snout beetle control research has been a priority for the farmers who guide the Northern New York Agricultural Development Program. The New York Farm Viability Institute provided additional research funding with the goal of limiting the spread of the pest to its current 9-county range in New York.

In 1989, Cornell entomologist Elson Shields and plant breeder Donald R. Viands began work at Peck Homestead Farm near Fort Drum, where ASB had destroyed 70-100 percent of the alfalfa there year after year since ASB invaded the farm in 1985.

ASB larva feed on alfalfa taproots, causing fields to look winterkilled (patchy with yellowed, leafless plants). Damage at the Peck farm also manifested in the milk check.

John E. Peck says, “We saw 25-30 percent loss in our milk production and as much as a 25 percent increase in production costs with the added expense of replanting every year or two.”

Shields estimates ASB-related crop damage can be as much as $1500/acre for the complete loss of a second-year stand.

Over time, treating the Peck fields with native entomopathogenic (insect-attacking) nematodes that feed on the ASB larvae caused the alfalfa snout beetle populations to drastically diminish.

Cornell Research Support Specialist Antonio Testa says, “The nematodes naturally recycle within the alfalfa snout beetle host, persist in the soil, and effectively self-disperse creating the opportunity for sweeping and perpetual control across treated fields.”

Peck says. “The success of this treatment is especially critical for us because we do not grow corn and rely on our hay crops.”

Cornell’s Cooperative Extension internship program supported outreach through Cornell students Joshua Knecht and Allyson Jones-brimmer, who engaged more than a dozen North Country farmers, including next generation young farmers, in raising the beetle-battling nematodes in 2009 and 2010.

The treatment combines two types of Northern New York-native nematodes that co-exist well. One prefers shallower soil, the other burrows deeper, broadening the effectiveness of the Cornell protocol.

The farmers working with the students mass-produced the native nematodes using small fish-bait cups filled with sawdust and waxworms. Each cup inoculated with approximately 15,000 nematodes produced approximately 25 million infective juvenile nematodes for field release. The newly-emerged nematodes were separated from the sawdust mix using screens and water. The rinse water containing the nematodes was applied to field surfaces through a variety of sprayers.

Two starter cups per nematode species were supplied by Cornell produced enough infective nematodes to seed start eight additional cups. Nematodes from those eight cups are sufficient to inoculate one 15-25 acre field and cost approximately $75 per field.

“Growers are able to inoculate their fields just one time to achieve long-term control. This eliminates the cost of annual applications of the more costly commercially-produced nematodes that persist in the field for less than a single growing season,” Testa says.

A step-by-step rearing and application manual developed by Jones-brimmer was field-tested and finalized with farmer input. Jones-brimmer says, “It is a pleasure to work with farmers interested in trying new things. Their comments helped me create a user-friendly manual to help other farmers.”

While Shields and Testa worked on biocontrol solutions for ASB, Cornell plant breeder Don Viands was selectively growing ASB-resistant alfalfa varieties, using varieties native to both New York and Hungary. Sixth and seventh generation selections were field-tested at Sheland farms with good results.

“Control with ASB-resistant varieties is quite possible. We have seen root damage scores consistently drop and believe we can achieve even better results with subsequent selections,” Viands says. “Seed companies participating with the Northern New York research project now have alfalfa with some ASB-resistance in commercial seed production for potential use.”

The next steps for the research team include documenting the ability for the biocontrol nematodes to persist across crop rotation. The typical rotation is four to five years of alfalfa and four years of corn before the field is returned to alfalfa production. The question is whether the nematodes will persist at sufficiently high enough levels to protect the subsequent alfalfa crops after the corn rotation.

The team is also working on developing an easy way for farmers to find a localized source of infective nematodes to start their rearing process each spring.

Testa says, “We are looking at the possibility of teaching farmers to bioassay soil samples from a field known to have nematodes to identify infective juvenile nematodes that can be collected to inoculate bait cups and support the on-farm field treatment from start to finish.”

Farmers interested in learning more about controlling alfalfa snout beetle and FFA and other students interested to participate with ASB control outreach can contact Tony Testa at 607-591-1493, at28@cornell.edu.

The “Rearing and Applying Nematodes to Control Alfalfa Snout Beetle” manual is online in the Field Crops: Alfalfa section of the Northern New York Agricultural Development Program website at www.nnyagdev.org