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.
Below is an alphabetical list of snow mold fungicides based on their level of efficacy.
Fungicides listed by efficacy
Typhula blight control
Microdochium Patch Control
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:
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