Key Tasks for June
Long range forecasts indicate June to be a mix of varying degrees of heat and unsettled conditions. In practice, that is likely to mean periods of hot, dry weather interchanged with significant volumes of rainfall. In both these instances the primary factor at play for turf managers will be water management. Something which is important because water (H2O) is the master variable which governs plant health. Adequate water availability is crucial to plant and soil function, with the key word being adequate.
Associated beneficial microorganisms drown in the soil, limiting plant defence and the mineralisation of nutrients for plant uptake. Like ourselves, plants also need to respire. It is commonly understood that plants photosynthesise taking in carbon dioxide from the atmosphere which is combined with water sourced from the roots, before going on to react with energy from the sun to make plant-available biological energy in the form of sugar. However, this process requires oxygen to keep all the electrons balanced and the cells healthy.
In the leaves, plants source this oxygen themselves as a bioproduct of the photosynthesis reaction. Root cells, on the other hand, still require oxygen for healthy function but are not capable of generating it themselves via photosynthesis. As a result, plant roots respire oxygen by sourcing it from the air pockets between soil particles. If those particles are full of water, the roots cannot function healthy and the plant suffers from abiotic (environmental) stress.
Like people and animals, plants are essentially tubes. Unlike people and animals, plants process water from the bottom up. This water transportation system starts at the roots, transfers into a network of transport pipes called xylem and ends in the leaves, as water escapes into the atmosphere through pores on the leaf surface called stomata. This cycling of water from roots up and into the xylem, and out through the stomata is called evapotranspiration. Evapotranspiration rate is the speed at which this process takes place, the warmer and drier the atmosphere, the faster the evapotranspiration rate.
When evapotranspiration has drawn water out of the soil, through the plant and up into the atmosphere to the extent there is not enough available water in the soil, the water level in the plant falls below the level required for healthy plant function. The result is a number of negative physical effects on the plant.
Wilting – the initial signs of water stress, caused when the turgor (water) pressure in cells falls leading the cell’s to collapse and plants to droop, or in the case of grasses to loose the ability to spring back up when walked upon. If the water content falls low enough the cells will die.
Reduced photosynthesis – lack of water is limited the plant diverts the available water to all systems, which limits or even stops photosynthesis the process by which the plant creates its own energy to fuel its metabolic processes.
Reduced respiration – as with reduced photosynthesis in the leaves reduced respiration in the roots leads to the reduction or halt of metabolic processes required for maintaining health roots.
Reduced Transpiration – transpiration is the vital process plants rely on to move nutrients and metabolic substances around their bodies utilising water pressure. Without adequate water this water pressure cannot be maintained and the system slows or halts.
In the soil – beneficial microorganisms are killed or sent into dormancy, water repellency of soil particles or surface material is initiated limiting the potential for subsequent rewetting of the soil. Nutritional elements and minerals cannot be solubilised into water films for transport into roots.
In both cases, excessive water or deficient water have a number of negative consequences both on the plant and the wider ecosystem within the soil profile. When plants are subjected to abiotic stress in the form of too much or two little water this makes them more susceptible to biotic stress in the form of pathogens such as anthracnose disease (Colletotrichum cereal), microdochium patch (microdochium nivale), brown patch (Rhizoctonia solani), or dollar spot (Sclerotinia homoeocarpa). All of which will be active when heat and humidity are the prevailing conditions.
Of course, given the understanding outlined above, it is worth considering that dry soils around roots which place stress on plants, can be also accompanied by humid swards and leaf surfaces due to environmental conditions on overcast showery days or, due to lack or inadequate irrigation which favour the activation, infection and proliferation of fungal pathogens.
As we can see, water is vital for a consistently healthy plant. The relevant point for anyone producing a sports turf surface is that a consistent healthy plant is paramount to producing a consistent sporting surface and, as turf managers, it is always worth reminding ourselves that our primary role is to facilitate a surface for play.
There are a number of management factors which promote adequate water management of a sports turf surface conducive to consistent plant health.
- Aeration – minimise and reduce compaction to create air spaces in soil and facilitate more effective surface water penetration and drainage.
- Surfactants – wetting agent programmes help to manage soil water. Penetrants overcome water repellency aiding penetration of irrigation and rain water. Block-copolymers hold water in the profile making it available to plants.
- Monitoring of evapotranspiration levels – a number of services and systems are available to record daily evapotranspiration levels in millimetres of water lost. Hard data on water lost enables calculation of water replacement.
- Moisture meters – regular readings from surfaces allows for determination of areas soil water volumes are approaching critical limits. This informs the requirement for water proactively, before the plant shows symptoms of stress.
- Irrigation – well serviced and maintain irrigation systems, with manufacturer supplied figures for water application rates in millimetres per minute allows managers to precisely replace water lost via evapotranspiration once moisture meter readings signal that soil water volume is approaching critical levels.
- Potassium – potassium regulates the closing response time of leaf stomata in reaction to water loss rates from evapotranspiration. Adequate supply of potassium thought out warm hot periods allows the plant to react faster to water loss, conserving soil water and postpone wilting.
- Seaweed – fresh cold pressed seaweed contains a number of plant beneficial bioactive compounds such as abscisic acid, cytokinin’s and gibberellic acids which stimulate a plants natural defence responses to both abiotic and biotic stress. Application of a liquid fresh cold pressed seaweed prior to stress events primes the plants responses in readiness, promoting increased tolerance and improved recovery.
Chafer grub and leather jacket monitoring
Chafer beetle traps should now be in place as part of monitoring within an integrated pest management system. Also, record sightings of crane flies to better plan application timings of entomopathogenic nematodes later in the summer.
At this time of the year, it is important that all machinery is in good condition and well maintained. Machinery downtime, due to lack of maintenance or poor set-up, can be costly. As the weather continues to improve, you will be all-out to keep your course in tip top condition.
Courses with their own workshop and mechanics will be at an advantage. Those without such luxuries need to be ahead of the game - all machinery should have been serviced and back in action by now.
Having a good wash down facility is an essentail tool for keeping equipment clean; it is a wise investment.
Ponds, lakes and streams - Inspect all water features on course, cleaning out any unwanted debris and litter. Some clubs arrange for their ponds to be dredged to clean them out while at the same time recovering any stray golf balls.
Tee boxes, tee markers and competition markers should be inspected daily, cleaned and moved to new tee positions as required.
Regularly empty litter bins/tee boxes.
Mark out trolley areas, out of bound site areas, ground under repair (GUR) and range markings.
Estimate and order seed, loams and fertilisers, fuels and other consumables.
As cutting frequencies increase, alter cutting directions and patterns to reduce the amount of stress from turning circles and the problem of grass ‘napping’. Remember to make large turning circles where possible, or to make three-point turns.
Tees, fairways and surrounds will require heavy divoting as volumes of play start to increase. The warmer weather and sporadic showers should allow for quicker germination and establishment. Similarly, any bare areas should also be renovated to try and reduce potential levels of weed/poa invasion as we move through the growing season.
The increased temperatures and sunshine hours will bring with it increased volumes of play. Whilst pressures to produce the highest levels of playing surface will be high, with many competitions and social events occurring, remember the importance of little and often aeration and topdressing. During warmer, drier periods, do not use tines that will leave large holes (e.g. slit tines), as the ability of the hole to fully recover will be lessened in these conditions.
With expected drier weather, irrigation systems will begin to be used more often. Ensure that all pop-ups and central systems are in good working order. Cleaning the system and ensuring the sprinkler arcs are in the correct positions should be major objectives. Trimming around the pop-ups and valve boxes will aid presentation and increase the speed of work during busy morning periods. Try to use the pop-ups when the surfaces need moisture, as this is better practice than applying water at set intervals or when there are few signs of stress. Also, check your water quality, what pH is it? Is it suitable for your green? Check filters on recycled water systems. Poor water quality will affect plant growth and sustainability.
Mowing frequencies can vary from daily to twice weekly operations dependent on the growth of the grass and the standards set by the course manager. Mowing heights may vary depending on local conditions, type of course, course expectations, sward type and mower type. The mowing heights are a guide, and will be subject to local weather conditions, but remember not to remove more than 1/3 of total grass height in each cut. The less stress that is placed on the grass at this vital time, the better the results further on into the season.
- Greens - Mowing height should be maintained at around 3.5-6mm.
- Tees - Mowing height should be maintained at around 10-15mm.
- Fairways - Mowing height should be maintained at around 15-20mm.
- Rough and Semi rough grass areas - Mow and tidy up these areas.
Changing of hole positions should be carried out regularly, however frequency will be dependant on a number of factors; green size, greens construction, tournaments, amount of play and condition of the green. During wet periods, it is likely the hole will wear more quickly, resulting in a crowning affect and surface wear. This wear is more apparent if the green has thatch problems. The hole will tend to wear quickly and form a depression caused by the placement of golfers' feet. Most golf courses are changing their hole positions at least three times a week.
Light topdressings of sand/rootzones are essential for maintaining surface levels preparation and again, 'little and often' being the ideal practice. Aeration should also continue, using a mix of micro, needle or star tines which give maximum effect and almost zero turf disturbance. Sarel rollers are another alternative; the main objectives being to 'vent' the rootzone and to allow water to move quickly from the surface and into the rootzone, thus encouraging the turf to root deeper.
Moisture management could also potentially be a key feature of the month. Now is the time to get ahead of dry patch with a wetting agent – prevention by applying them whilst the soil is still moist is much better than cure on baked hard massively hydrophobic soils. Many greenkeepers have invested in weather stations to inform of potential evapotranspiration rates within their sward. Remember not to let the soil dry out too much, but keep irrigation practices as natural as possible. Soaking the playing surface every few days is better than religiously watering at set schedules. Moisture meters are available to help you have a greater understanding of the situation beneath your putting surfaces.