Sunday, 19 August 2012

Fusarium Patch Plan of Attack

Fusarium, my fungal nemesis.
Well we are hardly through the summer but I am already starting to make my plan of attack for the coming fusarium patch (microdochium nivale) season. Ya I know, it's weird that I refer to the seasons by what diseases I have but that's my biggest concern. This year my approach is going to involve some serious prevention. This is due to the fact that this is not spring and the turf is only slowing in growth and its ability to naturally combat the fungal diseases is reduced when it's not growing. I will also be attempting to use only organic pest control products which don't work in the same way that traditional synthetic pesticides do. The effective organic pesticides only work when applied preventatively.

Our coastal climate is very tough for managing winter diseases. The winter temperatures are mild enough for disease activity but cool enough to almost cease any turf growth. We don't enjoy the insulating cover of snow but also don't have to worry about ice damage. Because of this cool wet climate we are often forced to make numerous fungicide applications during the winter to protect the slow growing turf from disease.

This year I am going into fusarium season with a few extra tools and strategies that I have picked up this last year.

Fertility: Beginning early September I will switch my nitrogen source over to Ammonium Sulphate. Studies show that increased sulphur levels have a detrimental effect on fusarium patch during some times of the year. I am also decreasing nitrogen levels sooner this year based on previous years growth data. The reduced nitrogen levels should help somewhat to reduce the lush turf conditions going into the wet season. It  is also a part of my bentgrass promotion program (see below).

Bentgrass in not affected by the
fusarium to the same extent
that Poa annua is.
Turfgrass selection: It's no secret that I have been working to increase the population of bentgrass on my greens. Some say it can't be done in my climate but I disagree. I currently maintain a private putting green that is 15 years old and is 99.99% bentgrass. We have never applied any fungicides to it ever as it manages quite well through the winter. It also has very little traffic but neither does my course when it's raining cats and dogs. Currently I don't have enough bentgrass to turn off the pesticides but I am seeing more and more each month. My hope is that next fall I will have enough bentgrass to allow natural selection to start it's magic on the Poa annua during the winter. This is a controversial topic is best left for another blog post if I ever work up the balls.

Organic Pesticides: I plan on using civitas throughout the winter but have my doubts. As civitas activates natural plant defenses it only makes sense that the plant has to be actively growing for those defenses to function properly. Maybe I'm wrong but that's just how I think. I will also continue on with my phosphite program but again the mode of action just doesn't seem effective during the cold winter months. I have heard some talk that the actual oil coating from civitas could prevent some disease activity but that's a long shot.

I plan on going out with full rate applications (currently do 1/4 rate applications weekly) every month or as required due to weather. I am having a hard time with this and will mostly likely play it by ear. Most of the data I have seen is from courses that experience prolonged snow cover which in a way preserves the fungicide application. Continuous rain and warmer temperatures, however, keeps the grass growing and metabolizing which uses up the pesticide quicker. I also want to keep my sprayer off the greens as much as I can. Less traffic = good.

I have seen some recent studies with phosphites and civitas but all of them were done on putting greens that were covered in snow for prolonged periods. I plan to see what can be done with these products when snow isn't an issue.

Synthetic Pesticides: I will continue to use the usual synthetics as needed to prevent catastrophic turf loss. Nothing new here. My ultimate goal is no synthetics but I'm not holding my breath. Hard to sell memberships and green fees with dead greens.

Cultural Practices:

  • Height of Cut (HOC): I will raise the HOC starting in October to help the turf better cope with the stresses. More leaf blade = more photosynthetic capacity in an already dark and gloomy period. Again, my purpose here is disease tolerance, not putting green performance. No one golfs here in the winter so why have greens that roll 9'-10' or more?
  • Aeration: I'm still on the fence but I think I am going to go without a core aeration again this fall and will instead continue with the solid tine aeration to keep drainage channels open. I plan on an aggressive core aeration next spring.
  • Rolling: Obviously haha. I plan to use my putting green trial to optimize my rolling frequencies to match optimum disease suppression. No longer will I only roll based on mowing frequency and weather. Again I have never done this and I'm pretty sure no one ever has before so this should be interesting to see. Slowed turf growth rates and soil microbe activity will be the biggest challenge as the turf will not be able to manage the stress of rolling as well as in the summer and the microbes will be less active. It will be all about a careful balance.
  • Mowing frequency: I will continue to monitor growth rates and will only mow when needed as predicted by my growth rate model. This should help keep stress levels down and prevent scalping as the turf is still growing all winter long.
All in all it will continue to be an eventful and busy winter. I'm going to need a roof and heater for my roller. Double rolling in 5C pouring rain....it's a possibility I'm not looking forward to.


Smoked with fusarium. Fairways are taking a beat down. They always recover without
the use of any pesticides.