Thursday, 6 December 2012

Yellow Patch 2 weeks later

Well it has been almost two weeks since my last post about yellow patch. Initially I was panicking due to the many unknowns that I was facing. I had never seen yellow patch (R. cerealis) damage turfgrass. Shortly after publishing that blog post I was inundated with information about the disease from other superintendents. Apparently I'm not the only one out there having difficulty with this disease on my greens!

 7th green Yellow Patch Nov 24
7th green Yellow Patch Dec 06, same location as above picture.
A fellow superintendent suggested to me that I try a nitrogen application. I immediately went out and sprayed an application of Ammonium sulfate at 0.05kg N/100m2 or about 9kg for all my putting greens or about $8 worth of product. This was basically the accumulated nitrogen needs for the turf for the winter months according the the growth potential calculations for my climate. If this proves to be a practical and effective means of control for this disease that would be great as an application of a pesticide runs about $600.
6th Green Nov 24
 Looking back at my nitrogen applications the last application was made on October 24 at about .01kgN/100m2. I had then stopped any further applications as it got quite cold in early November. In retrospect I think I should have applied the heavy "dormant" nitrogen application in late october no matter what the growth rates were doing. Maybe this would have helped my situation. In past years I had always applied nitrogen through the winter months as our climate is quite mild. This year I had reduced N applications significantly to try and combat the fusarium patch which I have been surprisingly successful in doing. Since the N application I have not seen any fusarium show up anywhere (not even one single spot actually!).
6th Green Dec 04
At the time of our discussion and my blog post I had no pesticides in stock. I ordered some as I had no clue if the nitrogen applications would make any difference especially considering the time of year. Well it has been two weeks now and I haven't been able to apply any pesticides to the infected greens. At first it was a shipping error and then heavy rains. Now it is a lack of water to fill my sprayer! I was able to spray some Iprodione on two of my greens but not the ones infected with the yellow patch due to wind. In either case I am now glad that I wasn't able to spray this green.
Incubated infected turf plug. Seems to be recovering.

Two weeks later it seems that the turf is starting to make a recovery. It has helped that the temperatures have risen a little this past week (average temp of about 6C). I am not only seeing signs of recovery on the sunny greens but also the shaded areas. Of course it is still very early and the winter hasn't even officially begun yet. I don't think I would have seen the results I am seeing if the weather was cooler. I will continue to monitor the disease and can now apply something if the disease decides to get nasty! I anticipate that if the temperatures drop slightly I might again have a problem. I can only hope that temperatures drop enough that this disease becomes inactive! Here's hoping for a deep freeze!

Greens in full sun are still synthetic pesticide free 5 months later!