You Are Here: Management Updates 1999 Archive June 3, 1999

Date: June 3, 1999
Category: Insects
Subject: Weevils, Weevils, Weevils

The insects are beginning to move - most white grub species have been feeding actively for a few We just returned from Westchester County, New York (on Wednesday, 2 June) and can report that the Hyperodes weevils seem to be slightly AHEAD of normal in development. Most of the population is in the largest larval stages, feeding actively, and causing damage in areas where populations exceed 40 or 50 larvae per square foot.

For golf course superintendents in southern New England (from Hartford south), check the suspect areas NOW. The easiest way is to cut a small wedge with a knife and look for larvae in the thatch. The larger ones are already beginning to move down into the upper root zone in preparation for pupation. For superintendents in central New England, watch the suspect areas closely - and look for the small larvae NOW. (Small larvae are often still up in the upper parts of the thatch.)

The only option for management at this point is trichlorfon (Dylox, Proxol), used as a spot treatment in areas where larvae are active. Note that some labels do not include Hyperodes (annual bluegrass) weevils, so in some states such an application is not legal. In other states, materials can be used as long as the site is labeled. Know which is the case for your state and act accordingly! Note too that even trichlorfon will not kill all the larvae, but often can knock out enough of them to allow the grass to begin to recover. And of course some of you can take advantage of the selective pruning and start overseeding with bentgrass.

Finally, once your sampling shows that a substantial proportion of the population is in the pupa stage (kind of diamond shaped and all white, no brown head capsule), it is too late to do anything. Bide your time, wait for the new young adults to appear, and consider treating the second generation at that time. (Right now it is too early to tell, but some of those second generation applications may go on as early as 23 or 24 June in Westchester county.)

Good luck!

- Submitted by: Dr. Pat Vittum