New approach helps combat alfalfa snout beetle

"The use of biocontrol nematodes is needed to reduce the intense ASB pest pressure, and the resistant varieties help to maintain the beetle at low pressure," Elson Shields, professor of entomology, told growers at an August field day at Sheland Farms in Belleville, N.Y., which has been hosting field trials for alfalfa populations that are showing some tolerance/resistance to ASB.

Elson and Donald Viands, professor of plant breeding and genetics, came up with the tandem solution.

The results of ASB-resistant variety trials at Sheland Farms and other northern New York farms have shown enough successive improvement that Seedway has initiated seed increase of an ASB-resistant Cornell experimental line, according to Seedway representative John Uveges.

Tony Testa, research support specialist in Shields' laboratory, and personnel from Cornell's Forage Breeding laboratory have collected ASBs by the thousands on northern New York farms for years for greenhouse trials at Cornell, where Shields and Testa developed a screening method to identify alfalfa seedlings with roots free from ASB-feeding damage.

Jamie Crawford, a research support specialist in plant breeding and genetics, has grown more than 150,000 seedlings over the past 10 years to be challenged with ASB in the greenhouse, selected resistant plants and completed the breeding work needed to develop the strongest alfalfa populations for field testing. Seeds from selected seedlings were then planted across northern New York farms for field trials.

At Sheland Farm, where a long-term ASB population exists, "we are very heartened by how good these trials look," said Julie L. Hansen, senior research associate in plant breeding and genetics at Cornell. "We have seen consistent yield gains and less root feeding damage over several cycles of selection. We are excited about a yield increase of 0.2 tons per acre over two harvests and think that this difference will continue to increase with more breeding work."

Seedway has initiated its seed increase project in Idaho using the most promising ASB-resistant alfalfa line developed by Cornell. "If all goes well, we should have commercial seed of the first ASB-resistant alfalfa variety available for planting by growers in spring 2014 at the earliest," Uveges said.

Shields said that ASB's major larval feeding period occurs in September and early October. The pests' larvae that have been deep in the soil will rise to the surface as soil moisture increases.

While northern New York is the center of the alfalfa snout beetle problem, Shields said: "These results are valuable far outside this region, because alfalfa snout beetle will become established elsewhere in time. We are seeing rapid spread of ASB in Canada, where they have not addressed it with any research of their own. We expect the growers there will be calling soon, and we will have the results of the northern New York research available to help them."

Provided by Cornell University