Using resistant varieties in combination with insect-attacking nematodes shows promise for controlling alfalfa snout beetles (ASB) on northern New York farms, say Cornell University researchers.
"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," says Extension entomologist Elson Shields.
Shields and plant breeder Donald Viands came up with the tandem solution.
The results of ASB-resistant variety trials on northern New York farms have shown enough improvement that Seedway has begun increasing seed of an ASB-resistant Cornell experimental line. “If all goes well, we should have commercial seed of the first ASB-resistant variety available for planting by growers in spring 2014 at the earliest,” says Seedway representative John Uveges.
To develop the resistant lines, Cornell researchers collected thousands of ASB larvae and used them to challenge more than 150,000 seedlings in the greenhouse. Resistant plants were identified, new lines were bred and seeds from selected seedlings were planted in the field trials.
At Sheland Farms near Belleville, where a long-term ASB population exists, "we are very heartened by how good these trials look," says Julie Hansen, senior research associate. "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."
Shields says ASB's major larval feeding period is in September and early October. Larvae that have been deep in the soil rise to the surface as soil moisture increases.
While northern New York is the center of the alfalfa snout beetle problem, "these results are valuable far outside this region, because alfalfa snout beetle will become established elsewhere in time,” he says. “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."