Abamectin

The stem gall nematode, Anguina pacificae (Anguina), is presently the most devastating pest of Poa annua putting greens in California. Larry Costello, a University of California Farm Advisor, who observed swollen stems on Poa annua (Poa) collected at Pebble Beach, first discovered this nematode in 1978.

Infection by the nematode causes the plant to swell creating a gall at the base of the stem. The galls appear as bulb-like structures near the crown of the plant and tend to contain either eggs and adults or second stage instars ready to emerge. As the hundreds of nematodes within each gall feed on the Poa annua plant, the plant is damaged and eventually killed through a combination of interference with water and nutrient transport, as well as nutrient deprivation.

Chemical and biological controls for Anguina pacificae are very limited. There is only one registered chemical, Nemacur (fenamiphos: Bayer Environmental Science) that can control/suppress Anguina without injuring or killing the Poa plant. Nemacur is the most commonly used product for suppression and control of Anguina pacificae. However, Nemacur will no longer be manufactured for use in California by June of 2007.

It will no longer be available for sale by June of 2008. Unless new emphasis is directed toward the development and review of products and management strategies to combat Anguina pacificae, golf course superintendents will have no viable tools or registered products in the near future to combat this devastating nematode.

In an effort to pursue alternative products and strategies to suppress/control Anguina pacificae, a two-phase field research program was developed and funded through the cooperation of golf courses located in Central Coast and Northern California (Anguina Field Research Golf Course Working Group), the Northern California Golf Association (NCGA) and numerous product development companies.

The objective of Phase One was to evaluate a group of insecticides, nematicides and biological products for safe use on a Poa annua putting green. Phase Two consisted of efficacy trials to be conducted at three local golf courses that have historically exhibited significant Anguina pressure.

The Phase One turf injury field trial was conducted on a Poa annua green located at the Monterey Peninsula Country Club in Pebble Beach, California. Ten products were evaluated including A-1641 (mustard seed: UniRoyal/Crompton), Agroneem EC (azadirachtin, AgroLogistic Systems Inc.), Avid 0.15 EC (abamectin: Syngenta), Biolizer (chitinous shells of aquatic origin and seafood waste, California Liquid Fertilizer), BioSafe Nematicide (peroxyacetic acid, BioSafe Systems Inc.), Dimethoate 2.67 EC (Micro Flo Company), Malathion 5 EC (Micro Flo), Neo-Tec S.O. (sesame seed oil, Parkway Research), ProMax (thyme oil, BioHumantics) and Vydate (oxamyl, Dupont).

Sequential applications of Biolizer, Avid, Vydate, Dimethoate, Malathion, ProMax and Neo-Tec were applied safely to Poa annua greens at 1x and 2x label rates. A-1641 at 20.0 lb. and 40.0 lb/1000 ft2, and Agroneem at 32 oz and 64 oz/1000 ft2 caused minor discoloration three days after treatment, but the Poa annua recovered quickly and no negative effects were observed 14 days after treatment. A-1641 did not dissipate rapidly into the turf canopy following 30 minutes of irrigation and was unacceptable.

All products were safely applied on Poa without significant injury or reduction in turfgrass color or quality. The Phase Two replicated field trials for suppression and control of Anguina pacificae were deployed on Poa annua putting greens at each of three locations including Cypress Point Club, The Links at Spanish Bay and Laguna Seca Golf Ranch. Different products were evaluated at each location. The objective of this multiple application, multiple location, efficacy field trial concept was to evaluate products that have shown potential to suppress and/or control soil borne nematodes in the hope of finding one or two active ingredients that exhibit some degree of suppression/control of Anguina pacificae populations while decreasing Anguina induced turfgrass injury symptoms. Prior to the first treatment deployment on August 10, 2003, check and treatment plots on each green at each research site were sampled for nematode activity. Each plot was inspected for Anguina activity and a sample taken from those turf areas exhibiting the most severe damage. One two-inch diameter core sample was collected to a depth of four inches from each plot. Monthly nematode sampling was conducted during August, September, October, November and December of 2003, and then January of 2004. Composite nematode samples were sent to Nematodes, Inc. for analysis of Anguina pacificae and soil nematodes.

Nemacur, Malathion, Vydate, Avid and Dimethoate were selected for evaluation at the Cypress Point Club. Biolizer, Merit (imidacloprid) plus Signature (fosetylaluminum: Bayer Environmental Science), Sevin SL (carbaryl), Agroneem EC, and ProMax were screened at The Links at Spanish Bay. At the Laguna Seca Golf Ranch A-1641, NeoTec, Biolizer, BioSafe Nematicide and Soil Tilth Program (macro and micronutrients, essential elements, humic acids and seaweed extracts: Plant Disease Clinic) were evaluated.

Turf and soil sampling showed a correlation between an increase in the number of Anguina galls and a corresponding increase in the Anguina damage value. This information may be of particular value when designing a control program that synchronizes application timing and susceptible life stages. From the soil nematode sampling data collected, there did not appear to be any positive trends associated with the application of a specific treatment and an observed reduction in soil nematode populations. The timing of turf damage cycles as induced by Anguina pacificae varied from golf course to golf course. At Cypress Point peak flushes of Anguina induced Poa damage were observed in August and October. At Spanish Bay a flush of Poa damage was observed in August, followed by remarkable recovery in September, followed by tremendous Poa damage in October and November. Laguna Seca showed very minor Anguina induced Poa damage during August, September and October with a peak damage flush during December and January.

In addition it is imperative that alternative control products and cultural management strategies continue to be evaluated and identified so that golf course superintendents have an efficacious and environmentally sound menu of registered products for control of Anguina pacificae on Poa annua putting greens.

Mike McCullough is the Director of Turfgrass Services for the Northern California Golf Association.

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