Rolling and Fusarium Patch - A Summary of Observations By Jason Haines

The following is a summary of my many blog posts about my observations about rolling and fusarium patch. The entire detailed articles can be found at http://penderharbourgolf.blogspot.ca/

This spring I initiated a small study to see what (if any) impact lightweight rolling had on silvery thread moss populations on Poa annua putting green turf. I used a small chipping green in our practice area and divided it into plots with different daily rolling frequencies of 0-8x daily. In late May I observed that the plots that were rolled had less fusarium than the plots that were never rolled. I collected the data and sent it into Dr. Larry Stowell at PACE Turf to be statistically analyzed. The following chart illustrates what effects rolling had on fusarium patch incidence on my putting greens in late May.

Obviously I was pretty excited about my findings. Until then I hadn’t heard of any cultural practices that I could do that effectively controlled fusarium during periods of cool wet weather. The only effective control for fusarium has always been fungicides and I am always looking for ways to reduce my pesticide use. I hypothesize that rolling has a similar mode of action on fusarium as it does with Dollar spot by increasing the beneficial microbial populations in the soil. I have no way to prove this on my site though. It could have been a number of things such as dew/guttation removal and bulk density of the soil. Clearly more scientific study is required.

Based on my observations of both disease incidence and turfgrass quality on my rolling trial putting green I decided to start rolling my greens 2x daily. I had been warned numerous times from turfgrass experts that rolling more than 3-4x per week wasn’t a good idea. In June I was now rolling 14x per week in an attempt to culturally control the fusarium. In June I rolled my putting greens 60x. Now I wasn’t rolling for green speed but as an important IPM tool. Rolling this much allowed me to raise cutting heights further reducing disease pressures.

Golf Tees show the Fusarium Patches on the Control Plot (never rolled ever)

I was forced to make a contact fungicide application in early June as I wasn’t totally convinced that rolling could completely control fusarium especially in a curative mode. I had a lot of very active mycelium and couldn’t afford any significant turf loss going into our busy season. I left a few areas unsprayed and it turns out that the fungicide application wasn’t necessary and the 2x rolled untreated turf easily outgrew the damage caused by the fusarium. The fact that I have been monitoring growth rates via clipping yields for the past year gives me a very valuable tool to determine when I can confidently hold off with fungicide applications and outgrow the disease.

This plot is rolled 1x/day. The cluster of disease suggests that the disease could be spread by a mower from a nearby control plot located to the top right of this plot.

I began using my trial green as an indicator to find the optimum rolling frequency for both turfgrass quality and disease suppression. It wasn’t until early July that I went back to rolling 1x daily as the plots that were rolled more were starting to get a little muddy with the heavy rains we were experiencing. By this time my attention had shifted from fusarium to dollar spot as the rains suddenly stopped and the temperatures finally warmed up.

This plot is rolled 4x daily

Going into fall, I plan on giving rolling a shot. I think that there is some potential for it to work combined with other cultural practices but I’m not holding my breath. Growth rates will be slowing and any additional stresses will be magnified. Typically stress = bad. Currently I am using phosphites and Civitas for disease control with really good results. Of course winter is a different story so falling back to the reliable synthetic fungicides is always an option. I will also be conducting a small study on my nursery turf to better see if rolling has an effect of fusarium in the winter months with and without different fungicide treatments. Stay tuned!

Poa annua rolled 8x daily with a HOC of 0.090" during full seed head flush with only 2 hrs of sunlight/day. Whoa! do you see what I see? Where's the seedhead? Oh snap!