For some this disease has become a real issue in the last few years, for others it’s a non issue.
Dollar spot seems to present differently for different areas, I know for Ireland fairways seemed to be affected more, and for the UK most seem to be getting hit on tee’s and green surrounds.
Research by STERF into 10 different isolates of dollar spot collected from 6 countries, concluded that strains from the UK were among the most aggressive, so we need to get ahead of this disease.
We had some golf courses in the South West event last week who had seen dollar spot pressure touching 20% this winter, luckily not reports to me of disease outbreaks, but for context the picture below I received from my French counterpart Baptiste, from the South of France taken this winter…
Click here to fill out the 2024 dollar spot survey (please!)
With the survey we are just as interested in those who HAVEN’T seen any dollar spot at their site, as this will help us:
A) Track where the disease is hitting currently.
Glenn ran a twitter poll in January asking for locations who’ve seen disease, from that we have a basic map but we’d love to get more detail. For example I know we have more than one incidence in Ireland!
B) Identify sites in the « Danger zone » who aren’t seeing disease, as they may be performing some cultural practice which is helping in this space for example.
So please do complete it, and encourage others to do the same, the more responses we get the more robust the conclusions we can draw!
And it’s all anonymous.
From the survey feedback we’ve had so far we have some early indications, but we’ll make a full report when we have even more completions.
On nitrogen
We know this has a part to play.
Whenever Syngenta run internal, or external (STRI), trials we see the highest dollar spot pressure at sites where we purposely bottom out the nutrition, much like we do for microdochium trials.
We’ve had a little look at those applying less than 70kg/ha nitrogen to greens per year, and you can see from that group 70% are seeing dollar spot on the putting surface.
Again we’ll wait on more data before making any sweeping conclusions, but its an early indication that fertility input levels have a roll to play.
On soil moisture
Dollar spot and water have a complicated relationship.
High humidity (moisture in the air) is one of the two inputs into the Smith Kerns model, and with all fungal plant pathogens water on the leaf is a driver for disease.
So whilst keeping your surfaces dry looks initially like the top priority, a dry root zone and wet leaf is the worst of both worlds.
Without adequate moisture in the root zone the plant can’t readily access available nutrition, and as we know water is also essential for many other plant processes.
Of those who target keeping soil moisture in greens below 20% VMC, 60% reported seeing dollar spot.
Again will be many ‘moving parts’ behind that statistic, species composition, how effective your irrigation system is at keeping you where you want to be etc.
But we know a stressed plant is more susceptible to disease, and low soil moisture will cause plant stress.
(20% will not induce stress at all situations, depends grass species, dry down rates of the substrate…. but we will need to watch where periods between irrigation cycles allow that 20% to plunge outside of healthy ranges…)
No easy solution here, where we can make less frequent heavier drenches of water work that’s going to reduce the leaf wetness factor. Consider a good quality wetting agent like Qualibra to help you hold onto applied moisture for longer between cycles, and move moisture effectively away from the immediate surface.
Looking forward to teasing out the findings from the final report to see if we can effect some improvements for this years dollar spot season, watch this space.
If you didn’t already read the review of last years dollar spot trials you can catch that here.
