Zachary O’Donnell ’27 spent the summer conducting field work at area farms with the Cornell Cooperative Extension Central New York Dairy, Livestock, and Field Crops Team, and the findings can now help Madison County alfalfa farmers make more informed pest management decisions.
O’Donnell’s work focused on sweeping alfalfa fields and gathering data on potato leafhopper populations, insects that damage alfalfa. Through this Upstate Institute Summer Field School research project, O’Donnell helped the team sample potato leafhoppers and their natural enemy populations in 31 alfalfa fields across eight counties in New York over five weeks.
“It is important for farmers to be aware of the abundance of potato leafhoppers in their fields since they can take action to reduce damage through cutting early or spraying pesticides,” O’Donnell said. “When spraying pesticides, there is a moment when it becomes less economical to spray than harvest or not spray, which is called the economic threshold. We calculated the economic threshold of the potato leafhopper at each site, each week, and relayed the information to farmers, so they could take necessary action.”
Donnell said, after analyzing the data, the team concluded that the leafhoppers’ natural enemies are not coming from heavily forested areas. Rather, predators originate on agricultural land. Given this fact, Donnell noted the importance of limiting actions such as spraying pesticides that may reduce these natural enemy populations.
Additionally, it can cost a farmer approximately $25 per acre to spray insecticides. Donnell said the data collected for this project helped illuminate areas that were over threshold and would benefit from harvesting early rather than spraying.
“Reducing spraying could save farms thousands of dollars each growing season,” he said. “As alfalfa is harvested four to six times a year, knowing whether pesticide sprays are warranted can help farmers save millions of dollars just in Madison County alone.”