Ricardo Jones

Chemical Review Manager

Risk Management and Implementation Branch I (RMIB 1)

Pesticide Re-evaluation Division (PRD)

Office of Pesticide Programs

US Environmental Protection Agency 

Ph: (703) 347-0493

Dear Mr. Jones,

It was brought to our attention that the Environmental Protection Agency (EPA) is considering 

restricting the amount of fosetyl-Al deployed across all agrochemical businesses. As you may 

know, fosetyl-Al is a phosphite fungicides that suppress fungal growth of Pythium species, 

Colletotrichum species, Microdochium species and likely many other fungi. There are benefits 

outside of fungal growth as well. My goal with this letter is to show the impact this product has 

had on the turfgrass industry and how reducing the use rate would significantly alter the 

progress we have made in environmentally sound management of turfgrass.

I am a turfgrass pathologist at NC State University and I assure you fosetyl-Al is an essential 

chemistry for managing putting greens, fairways, tees and even athletic fields in the SE US. 

Since 2008, our turfgrass disease diagnostic lab has received approximately 4,000 creeping 

bentgrass samples of which 50% (2,000), 18% (720), and 8% (320) were diagnosed with abiotic 

decline, Pythium root rot, and anthracnose. All of these issues are listed on the label for a 

fosetyl-Al formulation called Signature, and this product is extremely effective at keeping these 

issues suppressed during the golfing season. We have a rich history with fosetyl-Al at NCSU as 

my predecessor Dr. L.T. Lucas observed that a pigmented formulation of fosetyl-Al kept 

turfgrass alive during the heat of our summers. Over the past 25 years, numerous researchers 

including myself have documented the profound impacts of fosetyl-Al on disease management 

in turfgrass systems as well as the side effects of increased plant vigor. Reducing the amount 

of fosetyl-AL would cripple many disease management programs throughout the Southeast and 

indeed the US. Golf course superintendents are a clever bunch however, and they will find a 

substitute. Yet that substitute will likely not be a regulated product or a more toxic fungicide.

Fosetyl-Al has proven effective against diseases such as anthracnose, Microdochium patch 

(pink snow mold), Pythium diseases, and even dollar spot. Yet this product does more than limit 

sporulation of fungi or fungal-like organisms. It has been clearly shown that this product 

increases turf vigor through enhanced protection of rooting, stimulation of host-plant resistance 

mechanisms, and when formulated with a pigment (StressGard technology from Bayer) it 

enhances photosynthetic ability of turfgrass plants. Take all together, fosetyl-Al is a great 

product to maintain plant health in an extremely stressful environment. Although this product is 

frequently applied, we know first hand that it reduces the deployment of other fungicides such 

as chlorothalonil and mancozeb. Furthermore, this product has been essential in refining fertility 

and moisture management of golf course playing surfaces. As our research capabilities have 

progressed, we have only begun to understand the physical processes associated with fosetylAl. I suspect with the advent of rapid genomic sequencing we would see a plethora of hostplant resistance mechanisms stimulated by this product as well as up regulation of numerous 

genes associated with the photosynthetic mechanism. Fosetyl-Al is a unique fungicide that 
does more than simply suppress fungal growth. It has become a staple for managing excellent 

turfgrass with limited inputs in the Southeastern US. Reducing the use rate would greatly 

impact turfgrass managers in my state and throughout the US.

It is also interesting to note, that since the adoption of fosetyl-Al in the turfgrass industry the 

reports of fungicide resistance have declined. Leading to the early 1980s, numerous 

manuscripts detail the development of fungicide resistance to products such as benomyl, 

thiophanate methyl, cadmium based products, DMIs and dicarboximides. Recently almost all 

populations of Colletotrichum cereale are resistant to QoI fungicides such as azoxystrobin and 

pyraclostrobin. This likely developed prior to the widespread adoption of fosetyl-Al in golf 

course management in particular. Although this is just an observation and a theory on my part, I 

suspect that fosetyl-Al has reduced the selection pressure on numerous fungal plant pathogens 

and thereby has protected many growers from failures due to fungicide resistance. 

As I already mentioned, golf course superintendents are a clever bunch. They will find another 

product or suite of products to continue providing excellent playing surfaces for their customers. 

There is a surplus of phosphite products on the market, many are formulated as fertilizers. Yet, 

the quantity of fosetyl-Al or potassium phosphite in these products are difficult to ascertain and 

more importantly they are not regulated. Moreover, applying these products will likely result in 

the over-application of nitrogen and phosphorus because many of the fertility based phosphite 

products are linked with these plant macromolecules. Some golf course superintendents will 

chose not to use these products, but they will increase the amounts of other fungicides in their 

programs. To my knowledge fosetyl-Al has not been implicated as a potential carcinogen and is 

relatively a lower risk product compared to other fungicides. While I wholeheartedly believe that 

turfgrass management has little impact on the environment, yet removing this particular product 

could be a tip in the wrong direction for environmental stewardship. 

Finally, I want to discuss some recent research in our program. The phytobiome, or microbial 

populations associated with plants, has become a hot topic in plant science. Many scientists, 

including myself, believe that elucidation of microbial communities associated with plants will 

lead to novel mechanisms for managing plant health and plant diseases. As such, we 

investigated the influence of certain pesticides on microbial communities on turfgrass leave 

blades. Our hypothesis going into this experiment was fungicides likely reduce microbial 

numbers and thereby reduce microbial diversity. However, we found the exact opposite. We 

did not detect a difference between treated plots and non-treated plots and with fosetyl-Al 

treated plots we actually observed a slight stimulation of general bacterial and actinomycete 

communities. Currently we do not understand the ramifications of these findings, but application 

of fosetyl-Al does not affect microbial richness and diversity of turfgrass systems. I suspect the 

same results would occur in other economically important crops. 

In summation, I strongly disagree with the proposal to reduce the use of fosetyl-Al in all 

agrochemical businesses. I think this would have far greater impacts when growers and 

turfgrass managers seek alternatives that are likely more environmentally devastating than 

fosetyl-Al. Moreover, it would hinder progress in environmentally sound management of 

turfgrass systems and basically revert the industry to a standard set back in the early 1980s. 

Fosetyl-Al is an essential tool for turfgrass managers and frankly I do not understand the EPA’s 

proposals. I cannot see any benefits to reducing the use rate of this product, unless increasing 

the amounts of fertility and other fungicides is considered a benefit. I implore the EPA to 

reconsider this proposal. Pursing this reduction will significantly impact the turfgrass industry 
and will have negative impacts on the urban environment. Please reconsider the proposal 

reduce the use rates of fosetyl-Al. If you would like to discuss my views in further detail, feel 

free to contact me using the information below. 

Regards,

Jim Kerns, Ph.D.

Assistant Professor and Extension Specialist of Turfgrass Pathology

NC State University, Department of Plant Pathology

Campus Box 7616

919.513.4820

jpkerns@ncsu.edu