Introduction
This month we have experienced many days of wet and humid weather with intermittent heavy downpours of heavy rain. We expected this month to be dryer and warmer but I think this is following a trend of wet and warm summers we have had in recent years. This weather has been a challenge for us on the course with the wet weather slowing down the greens on the Stimp meter. It has also increased the levels of disease we have seen; usually this would be less common in summer. Luckily the weather hasn’t stopped us being able to cut all areas on the course but it has made the surfaces of the greens wetter and has affected the speed of the greens. We carry out ‘Stimp’ meter testing on a regular basis to monitor the speed so that we know what maintenance tasks need to be done to speed them up. On average we were getting readings of 9-10 feet but we wanted to make sure we remained just above 10 feet if possible.
After having a flush of growth following the wet weather we decided to double verti-cut, cut, then roll the greens. We then followed this with a light top-dressing to smooth out the surface. The verti-cutting also helped to remove some of the Annual meadow-grass (AMG) seed heads. We found that these combined treatments improved green speed and also surfaces smoothness. To feed the greens we applied a mixture of foliar fertiliser and a plant growth regulator (PGR) known as Primo Maxx. This helped to tighten up the sward and it also helped strengthen up the grass plant to defend itself better against disease and wear damage.
Disease Management
We noticed in the last month that wind has been blowing a lot of moisture from the cooling towers onto the golf course. This created a wet and warm microclimate on the golf course and encouraged turf diseases like Fusarium Patch (Microdochium Nivale) - that thrives well in warm humid conditions. The amount of disease we have seen in the last month has been more than we would expect to see in June. This prompted us to treat the greens with an application of systemic fungicide that enters the plant and protects it for a minimum of 30 days. The disease was particularly aggressive in this case so we found ourselves having to treat the greens with a second application as per the manufacturers instructions. We observed a fast reduction in the disease with minimum damage after treatment.
We have been keeping on top of the maintenance of the cylinders and blades on the greens triple machine by carrying out regular back-lap sharpening to keep them sharp. This process removes the dull edges and matches up the cylinders to the bed knife. The importance of this is to ensure we get best quality cut of the grass so that a cleanest cut possible is made. If the grass is torn instead of cut and an unclean cut is made then it can increase the chance of disease entering the grass plant after mowing.
Annual Meadow Grass (AMG) Control
The periods of heavy rain at the beginning of June gave the AMG all the moisture it needed to produce seed heads in abundance. This seriously affected the playability of the greens in relation to smoothness and trueness, and this led to a bobbly surface.
Some agronomists and greenkeepers in the industry actually encourage AMG in a ‘if you cant beat it, join it’ attitude. However, the more traditional bent and fescue grasses require lower inputs and can end up costs less. By applying fewer chemicals onto the greens it is better for the environment and also more sustainable. These traditional fine grasses are still more than capable of providing a smooth and consistent putting surface all year round. The problem with AMG is that to maintain it as your chosen greens species you need to spend a lot of money on it by using a high input management program described below:
Regular monthly fungicides applications to protect it against diseases it is susceptible to such as Fusarium
Increased applications of plant growth regulators (PGR) to reduce seed head production
More fertilisers to keep the AMG growing and to feed its high nitrogen requirements
Irrigation water because AMG needs a lot of water to keep it healthy
All of these requirements are costly and require high inputs of chemicals and materials. We are on a water meter at Drax GC, which has an influence on the amounts of water we can apply to the greens because of cost. The lower the height of cut you select generally increases the amount of water required in dry conditions and this increases cost; this makes the lower heights of cut (3.5mm and below) unsuitable for our club. For our course it is much more suitable to encourage the lower maintenance grasses such as fescue and bent grasses because they require much less money spending on them in comparison. Since keeping the height of cut no lower than 3.5 mm and reducing perimeter cuts we have seen a resurgence of brown top bents (Agrostis capillaries), creeping bent grass (Agrostis stolonifera) and fine fescues (Festuca rubra spp.) grasses in the sward. These grasses are starting to slowly reclaim the greens from the undesirable AMG. This is a step in the right direction and if we continue down this path we might be able to get the greens back to the condition of when an agronomist from the STRI identified us as having bent and fescue dominated greens.
To combat the AMG seed heads we have been regularly applying the PGR Primo Maxx mixed with a foliar feed as per its manufacturers instruction. These chemical treatments strengthen the grass plants and reduce vertical growth in favour of horizontal growth to tighten up the grass sward and make a smoother surface. The PGR Primo Maxx inhibits a hormone called gibberellin in the AMG so that it struggles to produce so many seed heads. This reduces its ability to produce seed and reproduce so that over time we will turn the tables and replace it with the bent and fescue species prefer.
Greg Evans (2009), master greenkeeper and consultant with the STRI, explains in "The Big Issue" that: “Primo Maxx is a great product which helps control top growth by putting a lot of the plant energy into the root system. By doing this, it has the advantage of reducing Poa Annua seed heads that appear every spring. These seed heads tend to cause slow bumpy greens at this time of year. If you start this programme early enough, coupled with a low cutting height, bumpy greens will be eliminated”.
This is evidence of the success of other courses using PGR’s to reduce seed head production and improve the quality of their greens. We have used elements of the program described by Evans (2009) with exception to the heights of cut that he advises. We try to go no lower than 3.5mm so that the fescues are still able to thrive. By doing this we want to get the best of both worlds by reducing the AMG and also encouraging the finer grasses in the sward so that they can take over and reclaim the greens. Since using this program we have seen a real increase bents and fescues on the greens and can slowly see them start to make a recovery.
As greenkeepers we have a responsibility to ensure the longevity and health of our greens but at the top of our priority list is to make the greens as fast and smooth as possible to perform well enough for players to attempt to sink those tricky 10-foot putts for par or even birdy!
Harnessing Bio-stimulants To Encourage Microbial Activity
The soil beneath your feet when stood on a golf green is an extremely diverse environment full of a large variety of micro-organisms. In “Grass Nutrition for Early Spring Growth” Martin Ward (2010) highlights the benefits of encouraging micro-organisms in the root zones. He explains that the root-zone harbours millions of microscopic organisms including; bacteria, mycorrhizal fungi, millipedes, beneficial nematodes, worm, and many others. These organisms help digest materials in the soil and make nutrients available to be up taken by the grass plant roots.
Bio-stimulants have been really popular in the industry recently with many people claiming benefits including disease resistance and healthier growth. We have trialled some of these this season and observed huge improvement to the grass health of treated areas compared to untreated areas.
We have reduced the amounts of iron applied to the greens in the start of the year because it can have a negative effect on the micro-organisms and sometimes leaves the grass looking yellow and sickly following treatment. The tradition treatment of adding lawn sand containing ammonium sulphate and iron was seen in the past as beneficial but it only works short term and they contain high levels of salts.
We always look at the salt index of fertilisers we use to ensure that we use products with a low salt index so that salinity in the soil is reduces as well as the potential for scorching of the grass. Laboratory soil testing of our greens has shown that the soil of our golf course has a naturally occurring PH range of between 6 & 7. This PH range is highly recommended to encourage fine turf species such as fescue and bents and also reduce worm activity because they do not like acidic conditions. It is important not to allow the PH to rise above 7 and become alkaline because you can encounter problems with nutrients lock-up, therefore reducing the nutrients available to the grass.
Some of the most popular bio-stimulants include: Sea kelp, humic acids, plant hormones, organic products, molasses, yeast extracts, and vitamins. Each one of these ingredients performs different tasks and they are all really important to improve the over all health of the grass plant.
Black Layer
One of the issues with the greens on the new land (3rd, 4th, 5th) is the black layer found about 3-4 inches below the greens surface. This layer is distinctive because it is black in appearance and has a strong foul egg smell. If left untreated it can cause damage to the grass plant by root breakage and a general reduction in the health of the grass plant.
As you can see from the photographs above, the aeration and top-dressing work we did at the beginning of the season has smashed through the black layer and started to dilute it with sand. This treatment helps to get air through this layer so that anaerobic conditions are reduced and the black layer starts to get broken down.
In the article ‘Black Layer in Turfgrass Management’, Butler (2009) explains that black layer is created when microbes in the soil break down organic matter while there are low levels of air present (anaerobic conditions). He suggests that this condition can be encouraged by conditions including: compaction, excessive irrigation, thatch build up, or sulphur application. Once the conditions have been created for black layer then the health of the grass roots is reduced dramatically because pores in the soil are filled with hydrogen sulphite gas. This gas is lethal to grass plants roots and kills them on contact causing root breakage and deterioration to the health of the grass plant.
The presence of black layer suggest that the greens on the new land required extra aeration at some point and this is good evidence to support the importance of regular aeration to avoid creating anaerobic conditions in the soil. Since identifying the problem we have concentrated on carrying out more aeration through the winter using the verti-drainer and the hollow core treatment combined with sand topdressing in the spring. Since doing this we have seen this layer break down and dilute it with sand so that in time we expect to see this layer break down entirely to allow the grass plants to send roots deeper into the soil profile and also facilitate and gas exchange through the root zone.
This week we have been verti-draining the greens to de-compact and encourage water and air movement through the root-zone. This helps to reduce anaerobic conditions. We are also trying to reduce the amount of water we apply to avoid water-logging and reduce anaerobic conditions in the soil.
Toad Rush (Juncus Bufonius)
Recently we noticed the presence of toad rush on the golf greens and the social club bowling green. Toad rush is a small, narrow leafed plant and looks like a small clumpy grass plant. It grows in small patches about the size of a 50 pence piece. Ideally we want to nip it in the bud to discourage it before it has chance to establish itself even more in the sward. This plant thrives is wet soils and areas that become water logged regularly such as ditches, ponds, drain lines and other areas. It likes growing on clay and sand based soils so it is ideally suited to growing on our clay push up greens. We have noticed it mainly on the 10th and 11th greens but are keeping an eye out for it on any others too.
Laurence Gale MSc (2013) suggests in "Wet conditions encourage Toad Rush" that the best way to control this weed plant is by removing the conditions that it seems to thrive in. It thrives in wet conditions so it is important to continue our aeration programme through the season. If there are excessive thatch layers in the profile this can act like a sponge soaking up moisture and leaving the green water logged so removing organic material is very important.
The most effective methods of reducing toad rush include:
Regular verti-cutting because toad rush does not like close cutting or being sliced through with the verti-cutting blades so scarifying and close cutting puts stress on it
Work on the greens drainage to ease the wet conditions that toad rush find favourable
Carry aeration regularly to dry out the surface of the greens
Spend time removing clumps of the plant using a knife, perhaps taking a couple of patches out each morning per green to reduce it over time
Spot treating it with the selective herbicide 2, 4-d using a small paintbrush to coat the plant leaves. This should be followed but putting bent/fescue seeds down to replace the dying plant
Strengthen/tighten up the grass sward on the greens so that the desirable grasses out-compete the toad rush. This gives it less opportunity to move in and establish.
References
Butler, T. 2007. Black Layer in Turfgrass Management. [On-line]. Pitchcare. Available from: https://www.pitchcare.com/magazine/black-layer-in-turfgrass-management.html
Evans, G. 2009. The Big Issue. [On-line]. Pitchcare. Available from: https://www.pitchcare.com/magazine/the-big-issue.html
Gale, L. 2013. Wet conditions encourage toad grass. [On-line]. Pitchcare. Available from: https://www.pitchcare.com/magazine/wet-conditions-encourage-toad-rush.html
Ward, M. 2010. Grass Nutrition for Early Spring Growth. Pitchcare. [On-line]. Available from: https://www.pitchcare.com/magazine/grass-nutrition-for-early-spring-growth.html