Alfalfa

Now is a good time to start scouting for potato leafhopper in alfalfa, as second-cut alfalfa grows.  Potato leafhoppers migrate up from the south in late spring to early summer.  While they may be present in first-cut alfalfa they’re seldom a problem.  But in the second-cut alfalfa numbers can increase rapidly.  Younger alfalfa is more susceptible to damage at lower leafhopper numbers.  Also, vigorous alfalfa can tolerate higher numbers, and stressed alfalfa can tolerate fewer – an important consideration should the current dry conditions continue.  If alfalfa is more than 7 day

Last week we reported that peak alfalfa weevil feeding damage occurs between 325 and 575 heat units (based on accumulation of heat units from January 1 with a base of 48°F).  The cool temperatures over the past seven days have slowed the accumulation of heat units and thus weevil development, though southern Ohio is now at the lower end of this range.  For more details on alfalfa weevil scouting and thresholds please see our April 13 article