August 2023 (Part 2 of 3 )
Carrying on from where I left off last time and covering the winter period continues........
Speaking of winter cover, Poa (winter grass) loves this time of year as you will have noticed. Winter Grass is such an adaptable weed to various conditions and far more adaptable than bent grass to cold, wet, sealed surface conditions which limits air and water movement into and through the soil profile that winter conditions provide, Bent Grass growth next to non existent at this time of year and with hundreds of different bio-types, some more susceptible to product applications that others management of this weed in greens is extremely difficult.
Late autumn / Early winter when the Bent was still growing enough we did needle tine greens to improve air and water filtration further into winter than normally would expect, this worked a treat for the first half of winter. However as we move further past the mid point of winter, the cold conditions contract the soil sealing the surface, needle tinning would help but the holes would take a great deal longer to heal creating bumpy surface conditions for an extended time,and provide the perfect conditions for even more poa to spread.
We have always had a very high percentage of Poa in the greens, many years ago we had the full arsenal of weapons, to at best keep it somewhat under control, this included the use of pre emergent followed by post emergent products, both of which were important to limiting new seed germination whilst attacking the already emerged plants as part of an overall program.
Unfortunately the only registered safe for cool season turf pre emergent control for winter grass in bent grass greens was taken off the market several years ago, in one hit, the main ingredient for any chance of long term success was gone. With only post emergent’s available, an existing high percentage of Poa, with more seeds germinating without control, ( as they say 1 year seeds is 7 years weeds), we faced a choice of persisting with the aim of control / removal of Poa from greens and treating it as a weed, with the high likelihood of extended periods of poor surface quality through thin bare areas developing and bumpy greens or re-focus our approach from control to management, stop treating it as a weed.
We chose the latter and as time has progressed new formulations of products have been developed to assist with this approach. Our objective, management of Poa in greens, is aimed in the first instance reducing the growth of winter grass with growth regulation products through its favoured period of high growth when Bent grass is not, thereby creating an even playing field between Bent grass and Wintergrass competition.
In the second stage, reducing the plants seed head development through hormone based applications, resulting in less viable seed making it to the soil profile, both of these measures also help with providing a smooth ball roll with less impact to play through the winter,/ early spring period where untreated prolific seedhead development would impact ball roll.
Finally, targeted applications to limit Poa growth during other periods when Bent grass is stronger to give an even greater competitive edge to it over Poa allowing Bentgrass to fill in areas where Poa would have been exclusive to.
Basically our objective is to provide a quality, healthy turf surface with smooth ball roll regardless of the presence of winter grass within it, though with it being more visible in winter than other times.
Judging by the continued overwhelming positive feedback regarding our greens with “true, smooth ball roll” the most common one, we have been successful to date with this approach.
Moving yet still talking Poa, you may have also noticed we have a little more Poa in Tee boxes and and other warm season turf areas such fairways than normal. Unlike our cool season turf areas of greens, we have a few product options at our disposal for Winter grass control measures in our warm season turf both pre emergent and post. Generally we apply pre-emergent to these areas, however even though there are a few different brands and active constituents, the majority of these products use the same / similar modes of actions, meaning resistance development can occur with repeated applications of the same group of products.
To assist with limiting the risk of resistance developing we regularly mix up our applications with different product groups, however with most "pre's" belonging to the same grouping, this proves a little more difficult. This past year we decided not to use pre emergent products on tees, and use a a different mode of action but less long term residual in Fairways, with the expectation we would need early post emergent control as our main application for control, just to mix it up and give us another option without relying on the same mode of action hence, managing the potential build up of resistance.
Another reason we chose to not apply our regular pre emergent applications this year to these areas is to give our turf a break, Most of these products, particularly the better longer term residual products, are what we term "root pruners" in that, despite being safe to use on warm season turf, they do stunt and restrict root growth in desirable turf, combined with cold temps, root growth can and does recede. What this does is delay Spring green up, extends the period where the turf is slow to recover from wear and damage. We noted last spring was particularly bad for this, taking at least till December for notable growth and recovery to occur. Whilst not the only reason, temperature and light intensity also contributed, we adjusted our programs for this year to address both these situations.
Now root pruning of a different type in other works around the course through winter, we have been busy tree root pruning selected areas around greens. When we have been moving holes lately we have come across a number of tree roots in some greens, it was also noted some green surrounds struggled through last summer, the rear of 12 green also struggled with thin week areas developing on the back left portion persisting through winter, shade and tree roots within the green providing poor growing conditions around the effected area.
Tree pruning has been undertaken to let more light and airflow in through the heavy canopy, and now with some targeted root pruning we expect an improvement in surface quality at the back of this green.
Other targeted areas include the 1st 3rd 4th and 6th green surrounds where tree roots are also under the green along with 4 8 9 11 13 15 holes 1st cut areas of which are in the process of being complete. Surface disruption to areas worked is to be expected with GUR relief available.
With limited resources our means of root pruning mainly consists of a root ripper attachment for the tractor, spades and an axe,/ old chainsaw, and whilst there are dedicated specialist root slicing machines on the market they are costly. Our method may cause greater surface disruption, take a little longer to achieve, but is the only means at our disposal to achieve this important preventative work and more importantly does work.
Tree roots vs turf, the tree will always win, will out-compete the turf for moisture and nutrients and certainly for light, shading out the turf in the process creating poor growing conditions for turf with thin weak and bare areas developing. For Bent grass greens the extra low mowing heights further increasing the poor conditions and allowing for the more adaptable Poa invasion.
Sure we can increase our fertiliser and irrigation inputs to counter to some extent but isn’t very economical or environmentally sustainable, so it is critically important we undertake selective tree branch pruning and root pruning through late winter periods so the turf can access the moisture and nutrients it requires for healthy growth and better resilience through summer without negatively effecting tree heath.
.That tree you see standing 20m in height most likely has a root surface area extending 60m.
Part 3 will hit the desktop in a few days which will bring us up to date so
Till next time
Happy Hooking !
