You Are Here: Management Updates 2004 Archive May 25, 2004

Date: May 25, 2004
Category: Insects
Subject: Annual Bluegrass (Hyperodes) Weevil

We have just returned from Westchester County (NY) with turf samples, and were very surprised to find annual bluegrass weevil larvae in all stages already. We used the saline solution technique developed by Nancy Consolie (formerly the technician in Dan Peck's lab in Geneva) to float larvae out of plugs. The "recipe" is 150 cc of table salt (or the cheaper agricultural version) in one liter of water. Submerge the plugs in a bowl and the larvae will float to the top.

We found several small larvae, medium sized larvae, and large larvae in our samples. I was very surprised to see large larvae this early in the season. So for those of you in the metropolitan New York area, this is the "heads up" to check any areas that are looking a little "off color" at this point. Large larvae will be visible just with visual inspection - they look like grains of rice with brown heads and will be in the lower thatch around the crowns. Areas particularly at risk include any expanse of annual bluegrass at fairway heights or lower. We usually see more damage along the edges of fairways, edges of greens, and edges of tees in the spring.

If you find heavy populations (more than 50 to 80 larvae per square foot), you might want to consider spot treating the most heavily infested areas. There are no non-chemical alternatives available at this point. Use a fast-acting insecticide that will move through the thatch. (The various pyrethroids don't seem to work very well once the larvae are this well developed.)

For those of you in central Connecticut, Massachusetts, and southern Vermont or New Hampshire, remember that Westchester County usually is about a week ahead in development. So you may well already have some small larvae active, and should start seeing some of the tell-tale wilting within the week, especially if we have some hot weather in the next few days.

Good luck!!!

- Submitted by: Dr. Pat Vittum