Tuesday, 7 April 2015

Controlling disease on tees and approaches without pesticides

This past winter I was inspired by research out of Oregon State University by Clint Mattox on alternate control methods for the control of Microdochium nivale. I wasn't ready to take the plunge on greens but thought that I could adapt their findings to my tees and approaches. They used iron sulfate and sulfur to get reasonably good control of the disease over the winter on poa putting greens. I wrote about my early success with this plan earlier this past winter.

My tees are predominately ryegrass and bentgrass with a tough of poa. My approaches and green surrounds are mostly poa but have some bentgrass as well.

A great deal of the disease control success can be attributed to the incredibly mild winter we have had. Despite the nice weather there were times of high disease pressure on the course. Early January we were socked in with fog and the disease exploded. The recent warm and wet weather has also set the disease going on the putting greens and approaches.

Here is my application record. Nitrogen applications are based on growth potential for bentgrass.
kg applied

I also applied Primo Maxx monthly throughout the winter in an effort to reduce the spread of the disease by mowers. We cut tees 7 times from October until today despite the warm weather.

The cost of iron sulfate for the winter was about $55. I don't know of many traditional pesticide applications on 3000m2 that are that cheap!

Now the use of iron sulfate is solely for disease control. Because of this I feel it is important to calculate the EIQ of this practice. In the past I applied nothing for disease suppression so my EIQ was 0. This year the EIQ from the sulfur in the iron sulfate is 629! The EIQ from the use of ammonium sulfate is 1188! WOW! That is a total EIQ of 1817! To put that into perspective the total EIQ on my putting greens excluding sulfur contained in fertilizer is about 1000.

This brings up the
Disease control on approaches. 
question of what the actual impacts of these alternative control measures are? Just because they aren't pesticides doesn't mean that they are safe, or less harmful for the environment. Either way I am torn. Do I continue to use "fertilizer" for disease control throughout the winter? Do nothing as I always have and suffer the less than perfect conditions? Or start using expensive traditional pesticides? If it comes down to perception, the do nothing is best, followed by the fertilizer method.

Thankfully I have all summer to ponder because, damn, the tees were sweet this winter.......

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