Sports Turf Agronomy Advice - May 2023

As we head into May, spring is once again proving to be a very challenging period for turf managers. Weather conditions have been far from ideal with growth the limiting factor in being able to recover from winter wear damage and produce surfaces for players.

Relatively mild day temperatures with good periods of sunshine alongside low night-time temperatures have put the grass plant under considerable stress. Soil temperatures have remained moderate, but growth is now starting to increase particularly in those areas with higher heights of cut, whilst fine turf areas with lower mowing heights are still slow to achieve the desirable consistent growth.

An overview of the weather statistics for April can be found below. As expected, the first half of the month had cooler temperatures and wet conditions compared to weeks 16 and 17. Nitrogen requirements had risen in week 16 but dropped again in week 17. Growth potential peaked in week 16 in-line with nitrogen requirements and decreased to 50% in the last week of April.

Click here if you want to review weather data in your region for April. To keep up to date with the weather throughout May visit https://academy.agrovista.co.uk/category/weather

Looking towards May's long-term forecast, temperatures appear to be increasing steadily with 15 days predicted to be 15°C or above, but crucially in relation to expected growth, there is only one night-time temperature predicted below 6°. This will be reflected in the daily growth potential increasing and consistently being above 50% which will correlate to sustained growth patterns.

Nutrition inputs

Nutrition applications should typically follow in response to growth potential and the plants requirements for nitrogen. Although, every site is different and will have its own unique circumstances and environments. Many will now be well into their programmed approach to plant nutrition for the spring with possibly two or 3 fertiliser applications already made (more in some environments). Given the recent weather challenges from the low night temperatures, many will also still be waiting to see much response from the latest application, depending when it was timed. The slight increase in temperatures towards the end of April initiated a slight increase in growth activity but with that came signs of the undesirable annual meadow grass (Poa annua). This grass will make up many sward compositions across the country and is doing what it does best…surviving… by setting seed.

The onset of seeding brings with it an undesirable impact on playing quality, performance and overall aesthetics. Although grooming can be deployed to physically remove the seed, in some instances, depending on the surface you manage, this can provide the perfect seed bed for those seeds which don't make it into the grass box and fall back into the sward.

When growth becomes consistent enough to provide even swards, it is key to manage this growth to ensure that even growth is achieved. An even sward increases playing quality of the surface being managed and in-line with this, plant growth regulators (PGR) can be used to great effect to help regulate the ability of the plant to produce more vertical green tissue via cell elongation.

This month is when PGR programmes get into full swing. Some may have already applied the newer PGR technology in the UK, Prohexadione- calcium earlier in the season, as this PGR works in cooler conditions. The prohexadione calcium disassociates in the spray tank and the acid form prohexadione is generated. Because the prohexadione is created in the spray tank it is in the correct form for plant growth regulation as soon as it is sprayed onto the plant. Providing temperatures are 7°C and above once it is absorbed, after 4- 5hours, plant growth regulation will commence. This allows for early applications which has the secondary effect of assisting in suppressing Poa annua seedheads. A key benefit of this active ingredient is that it regulates Poa annua closely aligned with the desirable perennial grasses in the sward. This restricts the ability of the Poa annua to pioneer the sward, by not giving it the advantage of being under less regulation whilst the perennial species are still being fully regulated. It's effect on seed head development reduces the impact on presentation and performance.

Pests

May can be the start of activity from the Chafer Grub (May Beetle), which is an ongoing problem for turf managers. We are currently waiting for an update on the full approval or emergency approval for the use of Acelepryn on chafer grubs in 2023 and this will be announced via Syngenta when they receive notification.

Tom Wood
B.Sc (Hons) | BASIS | FACTS