Department of Plant Biology and Pathology

Foran Hall, Room 366

Rutgers, The State University of New Jersey

59 Dudley Road

New Brunswick, NJ 08901-8520

turf.rutgers.edu

Clarke@aesop.rutgers.edu

848-932-6295

Fax: 732-932-9377

 October 15, 2014

Mr. Ricardo Jones

Chemical Review Manager 

Risk Management and Implementation Branch 1 (RMIB1)

Pesticide Re-evaluation Division (PRD)

Office of Pesticide Programs

US Environmental Protection Agency

Dear Mr. Jones:

 

I am the Extension Specialist in Turfgrass Pathology at Rutgers University. My area of 

expertise is in mycology focusing on ectotrophic root-infecting fungi, as well as selected 

foliar pathogens such as Magnaporthe, Sclerotinia, and Colletotrichum. I have had a 

research, teaching, and extension appointment at Rutgers for the past 32 years. Part of my 

job is to evaluate fungicides for their ability to control economically important turfgrass 

diseases and to make fungicide recommendations to turfgrass managers within the context 

of sound integrated disease management practices. My goal has always been to encourage 

turfgrass managers to reduce fungicide inputs on turfgrass sites whenever possible.

It has recently come to my attention that the EPA is re-evaluating fosetyl-Al for use on 

turfgrass and is considering reducing the allowable amount of active ingredient for this 

product for the control of turfgrass diseases. I have evaluated fosetyl-Al (the product for

turf is called Chipco Signature) for well over 20 years; first as an experimental material and 

then as a labeled turfgrass fungicide since 1996. Throughout this time, I have found fosetylAl to be an extremely effective fungicide for the control of anthracnose and Pythium 

diseases on turf with a documented record of safety when used according to label 

recommendations. 

Anthracnose and Pythium Blight/Root Rot are two of the most economically important 

diseases of turf. Anthracnose has become one of the most destructive diseases of annual 

bluegrass putting greens in North America and Pythium diseases affect all species of coolseason turfgrasses during the summer months in the US. Reducing the allowable amount of 

fosetyl-Al on turf would render this material ineffective for the control of these diseases (the 

current label rate of fosetyl-Al on turf is 17.6 lbs AI per acre per month).

As you know, fungicide resistance has become a major problem in the turfgrass industry. 

As a result, many fungicide chemistries are no longer effective against selected turfgrass 

diseases such as anthracnose and Pythium due to the development of fungicide resistance. 

In particular, the majority of golf course superintendents in the US can no longer rely on the 

benzimidazoles, dicarboximides, and QoIs to control anthracnose, and many have 

experienced reduced sensitivity to the DMIs for the control of this disease. Because of its 

mode of action, no cases of fungicide resistance have been documented for fosetyl-Al on 

turf diseases. As a result, turf managers rely on fosetyl-Al and chlorothalonil as the main 

means of controlling this disease and the amount of chlorothalonil allowed by the EPA for 
use on golf courses has become increasingly restricted over the past decade. As I mentioned 

earlier, reducing the allowable amount of fosetyl-Al for use on turf would render this 

material ineffective against this disease. This would likely result in golf course 

superintendents and sports field managers using higher rates of less effective products for 

the control of anthracnose such as polyoxin-D, fludioxonil, and fluazinam. The same is true 

for Pythium diseases on turf, with many fungicide chemistries (e.g., the phenylamides) no 

longer being effective or only effective at high label rates on many golf courses. Fosetyl-Al 

is a very important rotational partner for the control of Pythium diseases (as well as 

anthracnose) on turf. Removing this chemistry would result in heavy reliance on other 

fungicide chemistries increasing the potential for resistance.

With its systemic movement in turf, fosetyl-Al is one of the only materials that can be 

sprayed on the foliage of turf to control Pythium root diseases. Although other phosphonate 

materials (e.g., the phosphites) are also be translocated to the roots, many are not registered 

as fungicides and thus would likely be used illegally in place of fosetyl-Al if it were to be 

removed from the marketplace. Moreover, in my efficacy studies over the past 20 years, 

fosetyl-Al + the proprietary pigment in Chipco Signature has consistently been more 

effective than the phosphites for the control of anthracnose and often for the control of 

Pythium blight and root rot. 

In closing, I would strongly recommend against reducing the allowable amount of fosetylAl on turf, since doing so would essentially remove it from the list of efficacious products 

available to the turfgrass industry. If I can provide any additional information, please feel 

free to give me a call (908) 227-1190.

Sincerely,

Bruce B. Clarke, Chairman

Dept. of Plant Biology and Pathology

Director, Center for Turfgrass Science

Professor of Turfgrass Pathology

Ralph Geiger Endowed Chair