Introduction
A thorough renovation helps alleviate the wear and tear resulting from a season's play. This work is essential if a good bowling green is to be produced for the following year.
Aeration
Thatch removal and reduction is a key aim from the end of season renovation, as is the alleviation of soil compaction which will have been caused during the playing season.
The most effective means, excluding striping off the turf and then the thatch itself, is by using a hollow-tine machine.
Hollow tining, carried out at 50mm centres and using 18mm diameter tines will remove 10% of the surface area of the thatch and to whatever depth the tines penetrate to. By contrast 12.5mm diameter tines at 50mm centres will remove 5% of the surface area.
Overuse of hollow-tining can result in a surface which is soft and easy to wear. Traditionally hollow-tining was recommended every third year, but current practices undertake this operation yearly or every other year. It really depends upon the requirements of each bowling green and conventional practices should not dictate whether something is carried out or not.
If hollow-tining is not being carried out, then other forms of aeration will need to be undertaken. This will include both solid and slit tines.
Whilst any implement which is inserted into the ground will cause some amount of compaction, the benefits achieved by the use of tines far outweigh any disadvantages.
Overseeding
A similar or identical grass seed mixture as applied in the spring should also be given as part of the renovation programme, as this will help to produce a thicker sward in as short a time as possible. This is important considering that winter is fast approaching. If overseeding has to be carried out too late, it may be a waste of resources to proceed with the operation and consider waiting until spring and/or undertaking some turfing.
Turfing
Any turfing that needs to be done on the green can be completed either before the green has been top-dressed or alternatively after all the renovation work has been carried out. There is some flexibility here and it will be up to the groundstaff how they wish to programme this part of the work.
It is important that the correct types of grass are chosen and these will also need to blend in with the existing sward, otherwise a form of patchwork quilt effect could result.
The rootzone which the turf has been grown on must be compatible with the existing rootzone of the bowling green, otherwise problems with root establishment will arise due to there being a break in the continuity of water draining through the whole soil profile. If this occurs then roots may reside within the surface layer, resulting in a shallow rooted turf.
Top-dressing
If hollow-tining is not carried out, then some 2-4 tonnes per green should suffice, depending upon how much solid tining was carried out and the evenness of the green. This will be about 1 - 2mm depth of top-dressing applied evenly over the whole green.
With hollow-tining this would increase to
- about 7 tonnes for a single operation with tines of 12.5mm diameter and at 50mm centres,
- to about 12 tonnes with tines of 18mm diameter and at 50mm centres.
As a useful guide, the amount of material used for filling hollow-tine holes can be estimated by the following formula:
- 2 tonnes + 1 tonne per 1% of surface removed; thus if 5% of the surface area is removed, the amount of top-dressing required = 2 + (1 x 5) = 7 tonnes.
Settling of the material in the tine holes over time will require additional light top-dressings to be applied. This could become evident after just a week.
When replacing the material that has been removed in the extracted cores, any thatch layer present will have closed up part of the tine hole making it harder to work material into the green. This can quite easily reduce the amount of material being put back onto the green by 50% or so.
Fertiliser
The last feed on a fine turf bowling green should generally be in August.
An application of nitrogen after September is not usually advisable as this encourages soft, lush growth which is more prone to disease and susceptible to cold weather (frost) damage. All of this impacts on the quality of the sward.
If a tonic is required, this should be in the form of sulphate of iron which assists in 'hardening' the grass and produces a darkened green effect, or black colour if overapplied in areas!
Controlled release fertilisers are sometimes used for the autumn/winter (slow to no growth) period. They can release their nutrients either through dissolution in water, which is frequent during the wetter winter months, or if temperatures rise in short fluctuating periods.
The argument for these type of fertilisers over the winter period is that they respond to the weather, which in turn influences growth of the grass in 'favourable' conditions, allowing nutrients to be released which will somehow be of benefit to the turf. Light levels are considerably lower than during the summer and these also impact considerably on growth.
There is no real benefit to the grass plant, as additional nutrients, over and above those which occur naturally, will only artificially encourage growth for a short period of time, leading to a weakened sward. Working with and understanding nature appears to have been replaced with trying to out think and control it. It cannot be done and I doubt if it ever will be done. Plants naturally start to adapt themselves to the coming winter through hardening up in the autumn and this should not be interfered with for some misguided belief in improved growth through additional nitrogen fertilising.
A controlled release fertiliser can certainly be of benefit over the growing season, especially on very free draining profiles, but use over the slow to no growth winter period has been encouraged by some arguably ill informed advice.
Their use may be more acceptable on football pitches which contain a much harder wearing and aggressive perennial ryegrass. This grass is also less susceptible to, as well as being resistant to several, if not most, of the disfiguring diseases of fine turf. Additional forced growth on this grass out of the main growing season will not have such a detrimental effect as on the finer turf grasses.
Considering that annual meadow grass is usually a significant component of most bowling greens, forced growth during this period can have devastating and costly consequences.
This important point seems to have been lost, possibly through the desire to boost sales where they are not really of much benefit to the end user. An arguable point though.
Fungicide
A systemic fungicide applied towards the end of the season is sometimes given to aid disease prevention, particularly where the bowling green is dominated by annual meadow grass.
This application is then supplemented by a contact fungicide if the need arises over the winter.
It may be more cost-effective, however, to apply just contact fungicides where the green consists mostly of fescues and bent grasses and is also maintained and observed on a regular basis out of season.
Ditch Material
This is usually removed before renovation work commences, otherwise it will become contaminated with top-dressing, excavated cores from hollow-tining and other debris, making it much harder to clean properly.
Green Edge Repairs
The raising of bowling green edges, typically the first metre around the edge of the green, may be needed on a periodic basis due to sinkage.
Sinkage is mainly due to users clambering, or hopping, from the bank onto the green. In addition sinkage may occur where the green's rootzone is several inches above the kerbing. This can result in gradual erosion and collapse of the immediate edge and is especially noticeable during the dry summer months.
The edges of greens are also prone to drying out and one contributing factor could be encroaching tree and shrub roots. It is surprising how far the roots can spread and also what they will penetrate in their search for water. If drying out around the green edges, especially if within 3m (10 feet) of the edge, has occurred during the summer, it may be worthwhile carrying out an investigation to see if such roots are a factor.
If they are, then the bowling green edges can be stripped of their turf, the tree or shrub roots dug out and soil removed if desired. New soil can then be imported, if required, and even new turf replaced on the relatively small area of the works.
Bank Repairs
Once the green has been renovated, the perimeter banking can then be repaired.
Unless the banks are constructed with artificial material, which may still need some repair work, the grass banking will most likely need some work on it. This may be
- raising it up to meet minimum height requirements from the top of the bowling green to the top of the bank; or
- improving the evenness of the bank where depressions have occurred; or
- returfing where the grass has become thin or died out; or
- reshaping the bank to make sure the correct angle is achieved for the face of the bank.