You Are Here: Management Updates 2005 Archive July 7, 2005

Date: July 7, 2005
Category: Insects
Subject: Black Turfgrass Ataenius

I have received several phone calls this week from golf course superintendents up and down the East Coast, reporting grub activity from the black turfgrass ataenius (BTA). Calls came from New Jersey, southeastern Massachusetts, and Connecticut, among other places. While I have not confirmed the diagnosis (in other words, I have not seen the guilty parties myself), each superintendent described the grubs perfectly - small grubs (C-shaped, three pairs of legs, about 1/4 inch long) and often fairly gray on the backside. The timing is right for BTA grubs to be active, particularly in southern New England. (Note that BTA is only a golf course problem.) This is the only grub species that would be present in the grub stage at this particular time.

Here's a quick review of the BTA. Adults spend the winter in wooded areas near fairways and move out to the fairways in spring. Often you can see adults on the surface or in the baskets when mowing in late April. Females lay eggs in the soil in May, and these hatch into small grubs that begin feeding on turf roots. They go through three instars (stages of development), each lasting two or three weeks. They pupate (still in the soil) for about a week and emerge as new adults in mid summer. Some years there is enough time for the new adults to mate, lay eggs, and start a second generation.

Most years the insecticides that are applied to target annual bluegrass weevil (ABW) adults in spring also eliminate many of the adult BTA, which are active at about the same time. Imidacloprid (most often sold as Merit™ for golf courses) can be very effective against BTA grubs. Many courses in New England have been treating for ABW adults for several years and presumably minimizing BTA adult activity as well, so it had appeared that BTA populations were on the decline. But something about 2005 has been very much to the liking of BTA.

So be on the look-out. The telltale symptoms: turf appears to be under drought stress, often with a purplish tinge, but does not respond to watering. BTA grub activity often is more pronounced in areas that are moister (e.g., near sprinkler heads or in lower lying areas) and have higher levels of organic matter in the soil.

For the short term, if you find BTA grubs active, you can get some relief by treating with trichlorfon (Dylox™). It is very fast acting and breaks down quickly (in less than two weeks). Be sure to check the water pH - if the pH is higher than 7.5, use an additive to lower it because Dylox™ is very sensitive to high pH and breaks down in a matter of minutes. Remember to irrigate the treated area with at least 0.1 inch of water. Note that the tolerance level for BTA grubs is somewhere between 30 and 50 grubs per square foot at this time of year, so just seeing a few grubs does not necessarily mean you will need to take action.

If you are planning to treat with imidacloprid or halofenozide (Mach 2™) in the next few weeks to control the usual suspects (Japanese beetles, oriental beetles, European chafers), those applications should provide ample protection against a possible second generation of BTA.

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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