September had been a dry month until this morning. The monthly total up until the 26th September was a meagre 18mm but a short, sharp spell of rain in the early hours of the 27th saw an additional 11mm fall in a short time followed by 16mm on the 28th to bolster the monthly total a little. Temperatures have still been mild overnight giving us slowing but steady growth as the growing season draws closer to an end, but the next few days will see a noticeable decline in temperatures and therefore slowing growth even more.
Late September is generally the period when we see an increased risk of fusarium affecting the fine turf areas of the course, most damaging really to the green surfaces. Slowing growth and metabolism in the plant combined with an increase in moisture and cooler temperatures sees the fungal populations within the rootzone move to a position where disease pathogens can take advantage of the turf plant when it is subject to stress.
Autumn and early winter in 2020 was a prime example of a high-risk situation which ended up showing how damaging fusarium can be to greens’ turf. Mild, very wet and a huge amount of stress on the greens through very heavy golfer traffic set the plant, particularly the Poa, back which lead to the fusarium fungal colonies taking hold very easily.
Minimising the impact of fusarium is complex and managing it is far from passive. The two key points of action are:
Controlling moisture falls to cultural methods; dew removal through mowing, brushing, rolling and the application of dew suppressants on the short term. Long term practices such as aeration and topdressing also contribute to improving the overall growing environment and helping to move moisture away from the surface. Plus, producing an environment that does not benefit active fungal pathogens.
Physical stress on the plant will come from several sources, most commonly from mowing but daily foot traffic from golfers will also play a significant role. The best example of this is demonstrated by the incidence of disease on areas of the green that are subject to the most foot traffic, namely walk-on and off points such as the front right of the 16th green.
So how do we manage these sources of stress? The easiest way to reduce stress through mowing is to raise the height of cut (we are now mowing at 4mm), and to ensure that the cutting units are clean and sharp to reduce tearing and produce a clean cut with minimal damage to the leaf tissue. Reducing golfer traffic is more difficult and a little contentious…
Fertility is another factor that we use to reduce stress but most importantly to produce a plant that is healthy, resilient and competitive against attack from fungal infection and physical damage.
Choosing the right fertilisers, timing nitrogen inputs (so as to not produce strong growth flushes in autumn and winter), and using necessary trace elements at the right time of year to aid in cell strength and promote a strong immune system within each plant, are key factors when fertilising the turf.
After we have taken all of these practices and factors into account, watched the surfaces daily, made adjustments and concentrated efforts dependant on current conditions, we may still end up with (and usually do) fungal activity that is damaging the plant and surface. Our last resort from here is making an application of fungicide, and once again we come up against some complications.
Recent legislative changes to the fungicides that are available for us to use on turf have limited the products that are available to all turf managers, not just golf. We no longer have any “contact” fungicides, only products that act systemically. The problem with using systemic fungicides is that they will not treat an active, attacking fungal infection very well and therefore there will always be a lag in disease suppression following the application of these.
The only way to address this problem is to apply preventative fungicide applications but this could then contribute to the development of resistance to fungicides across the pathogen populations, catch 22!
Avoiding the development of fungicide resistance is the best case for following dedicated cultural practices to reduce the impact of disease and falling back to fungicides only as a last resort. The cost of this situation is that we need to accept there will be times when disease does have an impact on our surfaces.
We will be installing ropes and stakes to direct traffic through or around wet areas as the season progresses. Please respect these and avoid roped off areas to minimise damage to the course.
Undoubtedly worm casts will feature prominently on various areas of the course, causing both greenkeepers and golfers much heartache. We are trying two new management methods this season given that our traditional control methods are now unavailable. Bear with us on this, we will be doing our best.
Finally, I will keep banging the drum on pitch mark repairing; a small effort following your shot into a green will make a big difference to the putting surface that you are playing on.
Yours in sport.