Seasonal History and Chemical Control of European Chafer in Relation to
Degree-Days in New England Turf
Dr. Stanley Swier, University of New Hampshire, 3 years
($13,800,$13,200,$13,400)
Objective(s): 1. Determine the seasonal history of the European Chafer in N.E.
2. To correlate the presence of the insects life cycle stages to develop a degree day model
to predict their occurrence for best control. 3. To determine the pesticide application
window based on degree days for maximum control of late summer larvae.
2000 Results: Two golf courses were continually monitored for life stages of the European Chafer from spring to fall. The occurrence of life stages were correlated with degree days. European chafer populations were not as numerous in the plots as anticipated due to wet conditions. Overall, the cool wet weather delayed grub development by an estimated 2 weeks. The common consensus among turf entomologists is that the best time to treat grub populations is at adult flight to between 1st and 2nd instar. Therefore, the spray window computes to between 650-1500 degree days. The evidence strongly suggests that degree-days can be used to time spray applications over a wide geographical area. In 2nd and 3rd years of this project, the first year baseline data will be refined and validated.
2001 Results: Two golf courses and a the University of New Hampshire grounds were continually monitored for life stages of the European Chafer from spring until fall. The occurrence of these life stages was correlated with degree days. The various life stages (eggs, 1st instar, 2nd instar, and 3rd instar larva) occurred at these 3 sites at approximately the same number of degree days. The data from 3 sites in 2001 was very similar to one of 2 sites in 2000. There is no doubt that degree days will be able to be used to time chemical control. Chemical controls were applied from May until August. The ideal spray window for Mach 2 was very narrow, estimated from 900-1100 degree days, or early to mid July. The spray window for Merit or Meridian was much larger and ranged from 219 - 1580 DD, or 15 May to 14 August. The high rate of Merit and Meridian improved control only if used after 7 August.
