snow molds

First, my hypothesis is that the guy in Frank's post has chilling injury in his pants, not gray snow mold.

But, speaking of snow molds, we are starting to see some in this part of the world. We had an extended snow-cover that started in early Dec and as it has melted over the last 2-3 weeks pockets of snow mold have become apparent. I've been hearing about snow molds in golf courses but also in home lawns (particularly in low-maintenance lawns where the turf was very long and flopped over/matted down over the winter).

Since I have not received samples, I can't say for sure, but I suspect most of them are Microdochium (pink snow mold) since our snow-cover was probably not long enough for Typhula. And, even the pink snow mold is most prevalent on areas where the snow piled up extra deep, or in shady sites where melting was delayed.

John mentioned conferences, and though I am not the international-pathologist-of-mystery that he is, I did have the opportunity to participate in Nebraska's turf conference about two weeks ago. I talked about some of the work we've done at K-State with nozzles and dollar spot control.

While there I had some good conversations with Roch Gaussoin from U of Nebraska and Ty McClellan from the USGA. Ty and I have been playing tag to a number of turf conferences over the past few months--I've been running into him all over. Then, I also had a chance to meet my new turf neighbor Zac Reicher who is transitioning from Purdue over to the Cornhusker state.

And speaking of conferences, it is hard to believe that the GIS is coming up in just over a week. I'll be co-teaching a class with Frank and our colleague Phil Harmon on Monday. On Tuesday I'll be lending a hand at the "microscope class". I heard a rumor that Kaminski will be assisting in the microscope class too, but luckily my job description does not include keeping him in line :)

Another Good Winter for Snow Mold

As Megan mentioned we got hammered with snow last week. The total snowfall amounts vary but we received over 15 inches of snow! Yes it took me most of the day on Wednesday to clear my driveway, but a wonderful neighbor used his bobcat to clear "plow trash" at the end of my driveway. The picture was taken last Wednesday morning and I was clearing a path for my dog to use the restroom. Following the snowfall, temperatures plummeted! The high last Thursday was 7 and the low was -4, so I think the snow is going to stick around a while.

With the amount of snowfall we received last week that fell on unfrozen ground, it appears that this winter is going to be conducive for gray snow mold development. Gray snow mold is induced by two Typhula species- T. incarnata and T. ishikariensis. Other names for the disease are Typhula blight and speckled snow mold. All cool-season turfgrasses are affected by gray snow mold, but the degree of severity differs with turfgrass species and the length of snow cover. Persistent snow cover provides an ideal environment for the gray snow mold pathogens to thrive and infect turfgrasses. If snow cover persists for more than 60 days than gray snow mold is likely to be problematic. When snow cover persists for more than 90 days, gray snow mold is often very severe. It is important to have an idea of how long snow persists in your location to develop a successful gray snow mold management program. Fungicides that are efficacious in areas with low to moderate snowfall may not be effective in areas with high snowfall amounts. I know I have posted our snow mold trials before, but it never hurts to repeat things. The reports clearly state how much snowfall was recorded at testing location. So pick the most appropriate site based on your conditions and hopefully you can find a chemical or mixture of chemicals that work for your budget.

What happens if we experience a winter thaw do I need to reapply fungicides? This is a question we routinely get, however I have yet to experience a winter thaw. I know I have only been here for one winter, still the last couple of winters have been fairly harsh. It is frivolous to apply fungicides when the ground is frozen, so that is the first thing to check. If the ground is not frozen then the answer is maybe. We are working with commercially available ELISA (enzyme-linked immunosorbant assay) kits to determine how long chlorothalonil and iprodione persist under snow cover and in the absence of snow cover. This technology is used to determine fungicide concentration in fleshy fruits like apples. We have just received some new data that demonstrates that our extraction method works very well and we are eagerly working on collecting degradation data this winter. Along with determining how these fungicide degrade, we are performing inoculations in the growth chamber to figure out when we lose protection to Microdochium nivale. There is more to come with this research so please stay tuned!

One interesting side note we learned from this project is the actual concentrations of the pesticides in the bottle/tank and what is detected on the plant. For example, Daconil Weatherstik is 54% chlorothalonil, when mixed in 2 gallons of water per 1000 sq ft the concentration of the solution drops to about 16 %. Then once the chemical is applied and allowed to dry for one hour we can detect about 600 parts per million on and within the leaf. I don't know if anyone else thinks those are interesting numbers, but I sure did. This spring we are going to repeat this experiment and we plan to include a sample to test fungicide concentration directly from the nozzle.

Best wishes for a happy holiday season and a happy new year to all of our readers! I am heading to North Carolina this Saturday for the holidays, so this will likely be my last post for the year. Thanks to all of the readers and thanks to John for putting the blog together!

Jim

Odds and Ends

Parts of the Midwest have been relatively cool and wet and as a result we have seen a lot of Microdochium patch in our diagnostic clinic. If the weather remains cool and wet than Microdochium patch can become fairly severe and may warrant a fungicide application. There are many fungicides that work well curatively against Microdochium patch. For more specific information please consult our webpage: http://www.plantpath.wisc.edu/tdl/. At our webpage you can access our research reports, from which you can see what chemicals performed well in our snow mold trials this spring.

A few courses in Wisconsin have reported some minor leaf spot symptoms on creeping bentgrass. After talking with the superintendents, the symptoms were not severe enough to justify a fungicide application. Many superintendents throughout the Upper Midwest are still dealing with winter injury of Poa annua. One particular superintendent has implemented a fairly aggressive cultural program to encourage re-growth. He has aerified and dimple tined greens, along with a fairly heavy fertilization and a light topdressing. He has seen significant improvements and is well on the road to recovery.

Finally, Derek Settle at the Chicago District Golf Association has observed brown ring patch at several locations in the Chicago land area. Outside of Derek’s report, we have not heard reports of brown ring patch anywhere else in the Midwest yet. If you are struggling with brown ring patch or suspect you may have this disease please feel free to contact us. You can find our contact information on the website posted above.

Microdochium Patch (aka Pink Snow Mold)