For example, an alfalfa crop 10 inches tall would need more than one leafhopper per sweep to warrant control. Those insecticides, however, also kill beneficial insects.
A better option, Johnson said, is for growers to plant a leafhopper-resistant variety the next time they seed the field.
Finally, growers need to pay attention to harvest dates to avoid harvesting forage crops too late in the season.
"If enough stresses occur, growers really need to be aware of when they harvest the last crop," Johnson said. "Traditionally, for those in the northern part of the state, somewhere around Sept. 5 should be the last growing-season harvest. For those in southern Indiana, we probably can stretch that to around Sept. 15.
"This allows enough time to build those carbohydrate reserves before a killing freeze comes along, so we have a plant with a full tank of energy through the course of winter. And then, as we break dormancy the following year, enough reserves are there for a vigorous break winter dormancy crop."