NZ Sports Turf Institute
The management of the green during the off-season is important if a good bowling surface is to be provided for the upcoming playing season. While the bowlers can pack their bowls away for the winter months the same cannot be said for the management of the green. There are a number of aspects to think about over this period to ensure a good green is ready for the following season.
Full recovery from renovation before growth stops in winter
Playing season problems like tracking are the results of poor renovation practices, be it from late closing, insufficient autumn fertiliser or soil topdressing to fill the grooves adequately.
A complete recovery before winter (especially in cooler regions) is a must if a good green is going to be ready for play next season as the playing season today often starts in the spring before good cotula growth has commenced.
Close green early
While strictly not an off-season management issue, closing the green at the appropriate time has a major influence on the success of any off-season work undertaken on the green. Closing the green late limits recovery as soil temperatures can change relatively quickly and is one of the reasons why greens can play poorly early in the season. Full recovery generally takes 4 - 6 weeks of good growing conditions, depending on renovation goals and intensity.
Clubs in cooler regions should close early April, while warmer regions can close a couple of weeks later.
Apply adequate autumn fertiliser
Autumn is the main time to apply nitrogen fertiliser (e.g. ammonium sulphate) to give rapid recovery from the end of season renovations. Insufficient autumn nitrogen applications is one of the main reasons why greens are not in a suitable condition for play the following season. Playing catch up in the spring with nitrogen fertiliser can be very risky as such applications commonly results in disease outbreaks, leaf bruising etc.
Two - three applications of quick release nitrogen should be applied a couple of weeks apart depending on the intensity of the renovations. While overall rates may vary, totals in the range of 30 - 45 kgs ammonium sulphate (or similar amounts of N as an NPK fertiliser)/green should be used as a guideline.
Apply sufficient soil to fill grooves
The groove lines need to be filled with consolidated soil to avoid bowl tracking problems in the early part of the following season. A single application of soil is generally not enough to fill the grooves as the soil settles over time. Several topdressings are needed. The soil can be worked into the grooves by several methods including brushes, mats, small screeds etc. The aim of this soiling is to fill the grooves not to level the green - that comes later.
Picture right :- Partially filled groove lines requiring a second soiling.
The green should look 'green' after a watering at the end of the operation, so all the excess soil (rubbly) should be removed before the final watering. This rubbly soil that is removed off the green can be used for any levelling later on once the soil has settled in the grooves.
Improving thin areas on the green
A lot greens have thin or isolated bare areas on the green at the end of the season. During the off-season is a good time to address these, but they do require separate treatment and thus should be 'micro-managed' differently to the remainder of the green.
Before improving these areas, look at the problem to see why these areas lost cover in the first place.
Some possible reasons include:
- Scalping (e.g. cutting too low, area could be slightly high, poor mower set up).
- Wear on ends (e.g. poor rink movement, compaction).
- Isolated dry areas coupled with heat stress (e.g. areas outside clubhouse, concrete surrounds, greens surrounded by hedges etc).
- Summer diseases and pests.
Picture Left :- Unfertilised (left) apposed to spot fertilised
Once the cause of the problem has been identified, repairing these areas can commence. There are numerous methods that are used to repair such areas, but at all costs avoid the 'hope syndrome' - where you leave the area and hope it recovers well enough on its own. From experience this is not the case, and once this is realised the weather is too cold to do much about it.
These areas require additional inputs for the plants to fill enough to match both the vigour and density of the rest of the green, so the green can play consistently next season. Micro-managing can include a range of practises from:
- Weekly/fortnightly fertiliser applications until the complete cover has returned watering in well afterwards.
Picture right :- Bare areas stolonised early after renovation.
- Where new plants are required, reseeding with bulbils (cotula maniototo), seed (starweed) or groovings (cotula dioica and cotula maniototo) can be used. If using groovings for re-establishment use on old groover or sharp rake so stolon with both leaves and roots can be collected. Keep the seed and stolons moist for 2 - 3 weeks until established.
Once established remember to apply additional (more frequent) fertiliser applications as the plants will be younger than those in the rest of the green.
- Plugging out the weak or bare area is another option especially where a mature plant is required (e.g. on ends outside clubhouse). When using plugs make sure the 'donor plugs' are of similar leaf texture and firmness and large enough. Before replacing the plug, place some fertiliser (with minimal movement, drilling, vertidraining) 2 - 3 times during the off-season has been of benefit.
- Small slightly high areas where minor scalping has occurred due to mower 'rock' can be lowered by drilling closely spaced holes (portable drill, or soil test plugger) prior to next season.
Once the groove lines are fill of consolidated soil, any improvements in surface levels can be carried out. Ensure where wires are used or similar levelling techniques that involve screeding on wires or rails that these are put into a level with a theodolite or laser so height adjustments are made. Laying them on the existing surface will only create a 'mirror-image' of the green and not address any surface irregularities present. Use rubbly soil for this so that the cotula can easily grow through the soil and not seal and crust. Alternatively use laser levelling machinery where available.
Moss and Algal Slime
Moss and slime are Nature's colonisers of bare ground so as winter approaches, days get shorter and there is minimal drying moss and slime become more visible. If moss is a persistent problem, it is a good idea to treat before the end of each playing season. There is a range of moss and slime control products available (refer to the moss and slime control chapter in Establishment & Management of Natural Bowling Greens, or contact NZSTI for more information).
Sometimes poor control of moss is due to the application method. All the available products kill the moss by contact only so it is important that the moss is saturated before spraying (water should ooze out under gentle thumb/finger pressure) and the product is applied in a high water volume and good pressure.
Picture right:- Saturated moss test.
Early treatment of both will improve the chances of control. It is still not too late to control any moss in the green before growth stops before winter. This also will allow time for the cotula to fill in before growth stops.
Algal slime unlike moss generally only appears on bare areas. Overcoming the bare areas will reduce the slime ingression. When treating slime the products 'dry' the slime so it is best to apply such products when 3-4 days of dry weather are forecasted. Dry rake the surface once to remove the slime. Then ask the 'why' question so that the area can be improved long term.
Sclerotina minor is the most common disease that is seen on the green during the off-season. Cotula maniototo, cotula dispersa (to a lesser degree) and starweed are damaged by this disease. Cotula dioica is generally not affected and often colonises the damaged areas.
Such outbreaks occur during this period due to the cool humid overhead conditions with reduced drying combined with soil topdressings and nitrogen applications.
Shading (from trees, shelters or clubhouse) is often a catalyst for disease outbreaks, so walk the green every day and check these areas for cobweb-mycelium (the first sign of fungi activity) and treat when seen. Fortunately, this disease is easily controlled by the commonly used fungicides (except azoxystrobin, i.e. Amistar).
Due to its scarring pattern this disease has been confused with winter pythium in some greens.
Picture right :-: Sclerotinia minor thinning cotula maniototo in winter, but which will recover in time.
Porina and Sod webworm can still cause damage at this time of the year. If porina caterpillars are left untreated at his time of the year in cooler regions as the cotula growth is slowing, when activity is high the damage looks similar to a 'mini grooving'. Treatment at cooler times can also be not as consistent as the caterpillars don't come to the surface as often. So as with the diseases, it is important to walk the green most days to check for activity.
Control measures (e.g. chloropyrifos, diazinon or alpha-cypermethrin) are the same for both sod webworm and porina although the alpha-cypermethrin products generally require a higher water rate (e.g. 100L of water/green).
Only diflubenzuron (Sniper,Dimilin) differs in that it is only effective against the Porina caterpillar and not sod webworm.
The off-season is a good time to control any grass in the green that may have been there during the season or had emerged since renovation.
Grass control on cotula greens is generally undertaken with propyzamide (Polka or Kerb). This chemical is root absorbed so sufficient water needs to be applied for it to be taken up by the roots. This product also performs well in the cooler part of the year, so grass control can take place anytime from May - August. Moreover, propyzamide can damage starweed and is commonly used for starweed suppression in cotula dominant greens if starweed reduction is preferred.
On pure starweed, or starweed dominant greens, haloxyfop (Gallant) herbicide is recommended as propyzamide can damage starweed. Also this product is leaf absorbed so doesn't require as much water (50L/green) and works in warm/mild conditions, unlike propyzamide which is dependent on cool temperatures.
Other off-season considerations
If the green needs mowing during the off-season mow it. In warmer regions, mowing may be required twice a week - even in winter. This is particularly important on starweed greens. It is important that the leaf doesn't become too large and lush over this period of the year. Ensure that the winter mower is set high enough to allow for the increased softness of the green so no scalping occurs. Match the mowing frequency to the growth rate on the green. If there is some shading remember that these areas will not be growing as much (if at all) so cut these areas only when needed. This is also true in the early part of the spring when similar conditions prevail.
The off-season is a good time to have the equipment used on the green maintained. Have the summer mower checked and serviced so that it is ready for use next season. Club greenkeepers can change on a regular basis due to the voluntary nature of the job, a new greenkeeper when combined with the wrong mower set up (especially with new base plate) can be risky as they are often unaware of the correct set up.
So have the green's most important piece of equipment set up correctly for next season, especially if the club has a new greenkeeper. To avoid this situation it is a good idea to have the mower serviced by someone who understands bowling green mowers. It only takes five minutes to scalp a green, but it may take many weeks for the plants to recover.
This time of year is also a good time to check the sprayer for spray pattern evenness and if needed to replace the nozzles and have the boom set at the right height.
Transfer from the diary on to a wall planner (for the following season) when diseases and pests in particular arrived so you can be on the lookout around that time and be proactive if needed.
The NZ Turf Management Journal is printed quarterly (Feb, May, Aug,
Nov) and is specifically tai lored to the turf industry with a range of topical, technical and research articles, book reviews and trade information