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September 14, 2010

Here is another post that just came in on the loss of PCNB and potential replacements for this fungicide. It is from Dr. Joe Vargas at Michigan State.


As most of you know by now, PCNB may not be available this year, or in the future, for snow mold control due to a cancelation by the EPA. The law does allow distributors to sell any PCNB that they have in stock. It also allows golf courses to use any PCNB that they have in stock. What the EPA ruling does is prohibit the manufacturers from selling anymore PCNB to distributors or anyone else. Because we felt this would eventually happen, and for other reasons, we at MSU have been conducting studies in Northern Michigan at Tree Tops Resort and at the HTRC in East Lansing in search of PCNB replacements. The following suggestions for alternatives to managing snow mold without PCNB are based on 20 years of research. There may also be other fungicide combinations that may have similar efficacy, but these listed here are the combinations we have had success with over the years. Many of the fungicide combinations listed below already come as prepackaged combination products.

Snow Mold Species

There are two basic types of snow mold, Typhula blight, which is caused by two different species, and Microdochium Patch. Typhula incarnata, which is the major pathogen in southern Michigan and, during milder winters, in northern Michigan and Typhula ishikariensis, which is only found in Northern Michigan and is the most prevalent pathogen in more harsh winters are the two causes of Typhula blight in MI. Typhula sp. are more problematic on creeping bentgrass and perennial ryegrass. The other snow mold is Microdochium Patch, caused by Microdochium nivale, which is more of a problem in southern Michigan under snow cover. It is a problem throughout Michigan in the cool wet weather of spring and fall. Microdochium patch is more problematic on annual bluegrass.

Chemical Management

Below is an alphabetical list of snow mold fungicides based on their level of efficacy.

Fungicides listed by efficacy

Typhula blight control


  • Chlorothalonil
  • Fludioxonil


  • Myclobutanil
  • Propiconazole
  • Tebuconazole
  • Triadimefon
  • Triticonazole

Microdochium Patch Control


  • Azoxystrobin
  • Fluoxastrobin
  • Iprodione
  • Mancozeb
  • Pyraclostrobin
  • Thiophanate-methyl
  • Trifloxystrobin
  • Vinclozolin


  • Chlorothalonil
  • Polyoxin D Zinc Salt

Suggested fungicide combinations as alternatives to PCNB

The following are suggested fungicide combinations for snow mold control on greens and fairways in regions where snow does not cover the turf for long periods of time. These are also good alternatives for fairways where cost is a consideration, although complete control of the snow molds will not occur in years of severe pressure.

Chlorothalonil combination with:

  • Azoxystrobin or
  • Fluoxastrobin or
  • Iprodione or
  • Myclobutanil or
  • Propiconazole or
  • Pyraclostrobin or
  • Tebuconazole or
  • Thiophanate-methyl or
  • Triadimefon or
  • Triticonazole or
  • Vinclozolin or

The following are suggested fungicide combinations for snow mold control on greens and fairways in regions where permanent snow covers the ground for 3 or more months:

  • Azoxystrobin + Fludioxonil + Propiconazole
  • Azoxystrobin + Fludioxonil + Chlorothalonil
  • Fluoxastrobin + Chlorothalonil + Polyoxin D Zinc Salt
  • Myclobutanil + Fluoxastrobin + Chlorothalonil
  • Pyraclostrobin + Propiconazole+ Chlorothalonil
  • Tebuconazole + Chlorothalonil + Thiophanate-methyl + Polyoxin D Zinc Salt
  • Tebuconazole + Chlorothalonil + Iprodione
  • Triadimefon+ Fosetyl-Al + Iprodione
  • Triadimefon+ Fosetyl-Al + Trifloxystrobin
  • Triadimefon +Trifloxystrobin + Chlorothalonil
  • Triticonazole + Pyraclostrobin + Vinclozolin
  • Triticonazole + Pyraclostrobin + Chlorothalonil
  • Triticonazole+ Fosetyl-Al + Iprodione
  • Triticonazole + Fosetyl-Al + Trifloxystrobin

Pre-package 3 way mix

  • Instrata (Propiconazole + Chlorothalonil + Fludioxonil)

Dr. Joe Vargas, Michigan State



September 10, 2010

Here is some information for Dr. Jim Kerns, the new turf pathologist at the university of Wisconsin. It is the Wisconsin recommendations for snow mold treatments for this winter if PCNB is not reinstated.

From Jim Kerns:

Here is what we've developed for superintendents in Wisconsin as substitutes for PCNB.

1. Good: 2 oz Thophanate-methyl + 5.5 oz chlorothalonil (this is a great mixture for pink snow mold and moderate gray snow mold pressure)

2. Better: 4 oz iprodione + 5.5 oz chlorothalonil (once again great for pink snow mold and moderate gray snow mold pressure 2 oz propiconazole (microemulsion formulations) + 0.3 to 0.5 oz Medallion (excellent for high pressure sites, but it fairly expensive)

3. Best: 4 oz iprodione + 5.5 oz chlorothalonil + 2 oz propiconazole (microemulsion formulation) 4 oz iprodione + 5.5 oz chlorothalonil + 0.72 oz propiconazole (concentrated EC formulation)

4. Supreme: 7 to 9 oz Instrata 4 to 6 oz Interface + 2 oz propiconazole (microemulsion formulation)

Other pathologists are also putting together recommendations. I will post those as they become available.



September 9, 2010

Here is some important information from Dave Berg of Reinders, Inc. It is about the 'stop sale' order on PCNB just before the snow mold season.

In the past 72 hours, the professional turf industry has been made aware of an alarming situation regarding the availability of Amvac's PCNB fungicide. The attached letter from Amvac dated 9-7-10 describes the current situation regarding the EPA's 'Stop Sale' order on PCNB. In short, PCNB is not available today from Amvac and most likely will not be available for the 2010 fall season without a sudden and unexpected reversal by the EPA. Amvac already sought emergency injunctive relief in federal court over the weekend and was denied.

This stop sale order refers only to Amvac and the PCNB products is their possession. Current PCNB inventories of distributors, dealers, and end-users is not affected and may be sold and applied this fall. Per Amvac, virtually the entire 2010 season's new inventory for all U.S. distribution is still on the docks and can not be shipped. This action has caught everyone by surprise and needless to say all distributors are vigorously weighing options to replace PCNB and deliver cost-effective solutions for the industry.

We will share any new developments as they become known.

Dave Berg

Business Mgr

Reinders, Inc.


Here is the letter from AMVAC, makers of PCNB.

September 7, 2010
To: Terraclor, Turfcide and ParFlo Customers - United States
Re: PCNB – Stop Sale

Dear Valued Customers:

As you may have read from our press releases, last month the United States Environmental Protection Agency issued a stop sale order with respect to our PCNB product line within the United States on the ground that our product contained a trace impurity that is not listed on our confidential statement of formula (CSF). We were shocked and surprised at the order, as it was issued without any advance warning just as our main selling season was starting and related to an impurity about which we had notified the agency nearly 20 years ago.

By way of background, under FIFRA for each registered compound, a registrant is required to list in its CSF all components that either (i) constitute at least 0.1% (1 part per 1,000) of the compound or (ii) are determined by EPA to be of toxicological significance. In 1993, we informed EPA that our PCNB manufacturing process yielded a trace impurity. It was unclear then (as now) whether this impurity had to be listed on a CSF. The agency took that information without further comment. In 1998 and then again in 2005, that agency approved our CSF for PCNB without making mention of any of the trace impurity. Last June, we engaged in discussions with USEPA about our CSF with a focus on impurities and embarked upon what we thought would be a mutual effort to assess purity levels, manufacturing processes and our CSF disclosure.
Without furnishing any technical analysis, notice or opportunity to explain our position, the agency stopped sale of our product in August. Bear in mind that the stop sale order did not include any contention that our product poses any risk to health or the environment. Indeed we are talking about an impurity of less than 10 parts per billion or 0.000001%. We promptly called for meetings with USEPA to hammer out an informal resolution, but quickly determined that the matter had been effectively handed off to government lawyers.

In the interest of protecting our business and saving our season, we filed a motion for emergency
relief from the stop sale with the federal court arguing, among other things, that the issuance of the order amounted to the taking of our property without due process. Last Thursday, however, that court denied our motion. In making his ruling, the judge noted that although the agency’s actions were troubling and Amvac had been treated unfairly, the agency was legally permitted to take this action.

At this stage, we plan to amend our CSF and work as expeditiously as possible with USEPA to get this stop sale removed. We will also continue down the path of further litigation, as we continue to believe that the order is an abuse of process. However, there is no guarantee that the agency (or a court) will work through this issue in less than four months (which they are permitted under applicable law). As a result, we are not confident that we will be able to ship product to our customers in time for turf application in the late Fall and Winter of 2010. We sincerely apologize in advance if we are unable to supply your needs in time for your application. Nevertheless, we thought it best to give you ample time to protect your business interests as we work on this matter. We will, of course, keep you apprised of material developments as we learn of them.

Thank you for your understanding and support. We look forward to continuing to serve you when this storm passes. For your reference, we are also including a copy of our latest press release on the subject. If you have questions on the continuing status of this matter, please contact Jeff Alvis at 817.742.7423. If you would like us to send this note to anyone else in your organization, please contact Glen Anderson at 888.462.6822.