BOWLS
Autumn Renovation
THE dry summer encountered during 2005 has badly effected the visual and playing qualities of many bowling greens around the country. Excessive thatch levels, shallow rooting, and formation of localised ‘dry patch’ have resulted in bumpy surfaces with poor consistency. Problems have been further exasperated by the players’ demands for faster greens, resulting in the groundsman resorting to shaving the green even closer, thus putting further stress on the grass plant. As we approach the end of the season, the
groundsman needs to be reflecting on the above and putting together a programme of works to be accomplished in the autumn as soon as green closes. This is necessary, firstly to establish a uniform plant population and, secondly, to do all one can to reduce the chance of similar deterioration next season. It is also an ideal opportunity to correct minor inconsistencies in surface levels. Autumn renovation consists of five key procedures:
Scarification
The purpose of this operation is to control or reduce the level of thatch. Thatch is the spongy layer on top of the soil consisting of live roots and shoots and dead and decaying organic matter. Whilst a shallow layer of thatch is advantageous to provide a degree of protection to the plant crown, excessive thatch is the primary cause of slow playing surfaces. Thatch also holds moisture, reduces rooting depth and harbours pest and diseases. Gentle scarification and grooming can normally be carried out during the playing season, but autumn is the best time to carry out more aggressive treatments. The type of work and machinery required will depend on the degree of the problem. If we are only dealing with this season’s accumulation, traditional shallow scarification (5 - 10mm deep) in two directions may be sufficient. However, if a deep thatch layer is evident, probably accumulated over several years, then different equipment capable of working to the full depth of the thatch layer will be necessary. Recent innovations such a the Graden now facilitate a means of removing up to 12% of the surface area in one single operation. Deep scarification of this nature is sometimes refered to as ‘linear aeration’ and as well a removing thatch it also provides a very good environment for new seed to germinate. As part of the scarification process it is also
important to ensure that all debris is removed from the surface. This is best done in dry conditions using a combination of portable blowers, sweeping and mowing.
Surface Aeration
Aeration of the top 50 - 75mm of soil is of paramount importance as this is where most of the plant roots grow. Hollow tine aeration is often carried out to complement the scarification programme as a further means of thatch reduction. Shallow hollow-tining with small tines at close centres also provides lots of holes for new seedling establishment. Deeper hollow tine aeration is a practice where some soil exchange is required. This is often undertaken in situations where the underlying soil is of poor quality, whereby cores of soil can be removed from the profile, to be replaced by a sandy free draining material. Localised hollow- tining can also be useful when done with a hand fork to gradually reduce the level of high areas of the green. Even where hollow-tining is not required a sorrel roller can by very useful to ‘prick’ the surface and create a better seed bed.
Overseeding.
If the green has been maintained in good condition all season, then overseeding may not be necessary. However, if the sward is thin or the surface completely void of cover, overseeding will be paramount to creating a good surface for next year. As soil temperatures reduce there is less chance of good seedling germination and development, therefore the renovation process needs to be completed as early as possible. With regard to seed type, typically a mix of Browntop Bent, Chewing and Slender Creeping Red Fescue would be used, but this needs to be matched to the specifics of your green (eg, Bent is more adaptable to very close mowing tolerances, but Fescue is more disease and pest resistant). The latest cultivars of Dwarf Ryegrass may also be considered for greens which receive particularly high levels of wear. The most important aspect of the seeding programme is to ensure good seed to soil contact. It is no good just spreading seed on the surface and hoping that it will grow. We have discussed earlier the benefits of scarification and aeration to assist in creating an improved seed bed. Following germination of the seed, it is also imperative that mowing heights are raised to a minimum of 7mm to allow the new
seedlings to develop. Top-dressing
The application of a sandy loam or other free draining material provides the basic means of correcting poor surface levels. This procedure also provides some protection for seedling germination and is obviously necessary if a soil exchange programme is to be undertaken along with the hollow tining operation. The top- dressing material can be applied by hand or mechanically, but to be worked in to the surface correctly it must be left to dry. The top-dressing can be worked in to the sward by brush or drag- mat but, if surface levels need to be corrected, the best way is to use a large trulute which will ensure that the bulk of material is deposited in the lowest areas. The rate of application will depend on the degree of problems to be addressed and will obviously be greater if hollow tine holes need to be filled.
Deep aeration
All the operations described so far have been related to the upper surface of the soil profile. We also need to remember that ultimately the health and quality of the grass sward depends on what is down below. Over time, the lower soil profile can become very compact leading to poor root growth and reduced drainage properties. Deep soil aeration has traditionally been carried out by laborious ‘forking’ of the surface. More modern machinery like the Verti- drain can complete this task quickly and efficiently and is ideal for dealing with deep soil compaction problems or where a compaction ‘pan’ has been created through regular shallow soil aeration.
In conclusion, the completion of an effective autumn renovation programme will go a long way to ensuring a healthy sward and better playing conditions for next year. As a final note, the greenkeeper needs to be vigilant throughout the winter period to ensure his good work is not negated by the damaging effects of fungal disease or excessive worm activity, and that a sensible fertiliser programme is followed to ensure the good development of the new seedling sward.
David Whitaker MG Sports Turf Consultants UK Ltd
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