You Are Here: Management Updates 2006 Archive August 28, 2006

Date: August 28, 2006
Category: Insects
Subject: White Grubs

White grubs are definitely on the move. We have seen second instars in several locations in western Massachusetts, and have had reports of third instars (probably European chafers) in eastern Massachusetts.

And to add to the confusion, there are several farmers in western Massachusetts who are losing hay fields to June beetle grubs. Unfortunately for them, there are no control alternatives at this point. That species is much harder to handle than any of the one-year life cycle grubs, and the farmers have very few chemical alternatives.

But for those of you maintaining fine turf (golf courses, athletic fields, home lawns, and the like), you have some options. While we are probably past the point for imidacloprid (Merit™) to be effective, there is another product that is very similar chemically that claims to have more curative power than Merit™. This "new" product is chlothianidin, sold as Arena™. We have not tested late season applications in Massachusetts, but colleagues in New Hampshire and Ohio report that it has been very effective, even when common sense would suggest it should be too late.

And for those of you who have access to trichlorfon (Dylox™), we are entering the period of time when it is appropriate to use. Most eggs have hatched by now and grubs are getting larger day by day. Dylox™ is very fast acting and will kill grubs within a day or two, but will break down within a week or two. Note that Dylox™ cannot be used on school grounds in Masschusetts, and cannot be used anywhere in Maine. There may well be other restrictions in other states.

Whatever you do, be sure to water the area with at least 0.10 inch of water as soon after application as possible.

And finally, for those of you who have written me and suggested that I look into some non-chemical alternatives for grub control, you might be interested to know that I had arranged to conduct a field trial applying one promising nematode over an acre (leaving a few areas untreated for comparisons). We had planned to put out that test last week, which would have been perfect timing. About three weeks ago, the supplier notified me and said, "So sorry, we don't have any product."

So... I contacted another supplier, who agreed to provide enough nematodes to treat five acres. (We were going to purchase these nematodes - so it was not going to be a "hand out".) On Tuesday of last week, that supplier called me and said, "So sorry, we have had a collapse in our production line and we can't get anything to you until the second week of September." We will go ahead and put out a small scale trial (two acres), but I am concerned that the application will be too late to be effective against the rapidly growing grubs.

Therefore... in my personal opinion, until suppliers of nematodes and other non-chemical alternatives can improve on their reliability in delivery (and quality control of the product delivered), we are a long way away from wide-scale acceptance on biological control of grubs in turf.

Submitted by: Dr. Pat Vittum

DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The author and the University of Massachusetts are not liable for any consequences of any pesticide "recommendations". Mention of any trade name is not to be considered endorsement of a product.

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