Turf soil pest challenge for 2023

A open letter to golf club committees from Glenn Kirby in support of golf course managers

For Golf Club Committees

Turf soil pest challenge for 2023

Chafer grubs and leatherjackets pose significant challenges for turf managers. When they feed on the roots of grass plants they weaken or kill turf, while their presence makes surfaces highly vulnerable to extreme damage from animals foraging for food.

A 2020 survey of greenkeepers found that only one percent of responding golf courses reported no damage from insect pests – a hugely worrying statistic. For some courses, the damage is devastating, while for others it is an obstacle to achieving great putting surfaces.

New research is helping to identify and refine turf managers’ control options to keep pest populations at sustainable levels for acceptable turf quality. The strategies will undoubtedly reduce damage, but their success will depend on seasonal pest pressure and the results from each step in an integrated approach.

Changing climatic conditions in recent seasons have proven favourable for some of the pests’ life cycles and prolonged their breeding activity. Furthermore the removal of historic pesticides containing chlorpyrifos and imidacloprid, on both the golf course and surrounding farmland, has left courses with few curative options and vulnerable to increasing insect numbers.

More recently, pest management strategies using modern products have utilised an emergency authorisation to apply Acelepryn. However, greenkeepers and turf managers are only permitted treat an area equivalent to 10% of their managed area, that can leave other areas vulnerable to attack.

Acelepryn application in the summer or autumn, when insect larvae and grubs are juvenile, is essential to get the best control levels. There are currently no spring control products for established larvae populations available on the market. And even with a full Acelepryn registration, it’s best to use its one labelled application per year targeted at preventing juvenile larvae from establishing.

Drought of 2022

The drought of 2022 may have reduced leatherjacket populations in unirrigated areas, such fairways. The good news is that last year’s heat and drought reduced adult crane fly numbers reported in PestTracker.

Furthermore, the drought is unlikely to have affected chafer grub populations, as they appear pretty resilient to dry conditions.

The lack of rainfall last year did pose a real challenge for course managers targeting treatment applications for chafers in the summer months, where prolonged periods of soil moisture are necessary for successful opportunities.

In late autumn, suitable treatment windows for leatherjackets were also difficult to find, particularly when the cold weather hit in late November and early December.

What will Spring 2023 look like?

The turf quality challenge arises when the pest larvae population are so high that it overpowers the turf, or we have a cold spring that does not allow the putting greens to “outgrow” the larvae feeding.

Leatherjacket populations are expected to be lower in 2023, but low populations can still cause significant damage if the weather stays cool and does not support good turf growth.

Chafer populations will not have been affected by the dry soils seen last year, and unirrigated areas will have significantly weaker turf.

With the challenge for applications last year, where Acelepryn was permitted and budgeted for, will leave some areas of the course, such as fairways and carries, at high risk of chafer damage. There is particular threat from foraging animals, especially in cooler periods of the year when other food sources may not be available.

What can we do?

A robust insect management program involves many different strategies, including the use of:

  • Acelepryn in high-pressure and high-risk areas in the summer for chafers and autumn for leather jackets
  • Increasing bird populations, such as starlings, can help reduce leatherjacket and chafer numbers
  • Small-scale monitoring of leatherjackets during the winter can help establish population levels and spring strategies
  • Spring sheeting in areas of high leatherjacket pressure
  • Assessing the impact of aeration on leatherjacket population dynamics – and adjusting timing accordingly.


Additionally, good turf health is crucial to ensure that the grass plant is as resilient as possible, to maximise the chance of delivering a good surface. This may involve:

  • Adequate nutrition
  • Removal of trees that cast shade or reduce air flow
  • Installing irrigation to support turf during dry summer conditions
  • Upgrading spray equipment to improve the chances of hitting the right application windows.


Research has shown that integrating strategies and actions together and getting the timing right can significantly reduce leatherjacket populations.

What about Nematodes?

A lot of work had been done looking at nematodes and improving how we integrate them into insect management solutions in turf. The technology has been available for some years, but frequently with extremely variable results. Now, with a better understanding of the specific nematode species required for each soil pest, how they work and what we need to do to achieve more consistent results, they do have a significant role to play.

Nematodes offer an interesting way of increasing overall efficacy of soil pest control, but don’t offer much support in a cold or dry spring.

The best way to use them is to integrate them into a programme at appropriate timing to target young larvae soon after egg hatch.

This is when the pest is most vulnerable and when soil temperatures and conditions are usually more suitable for optimum nematode activity.

Targeting leatherjackets with nematodes in an integrated strategy in the autumn is the most effective method, as the nematode species that will control leatherjackets is effective when we have 3 to 6 hours a day of at least 8°C soil temperatures. This is rarely reached until mid-April, so it’s not a strategy that will work for many in the spring.

When targeting chafers, we use a different species which is only effective when soil temperatures are consistently above 12°C for 3 to 6 hours of the day, which is rarely reached until June for most parts of the UK.

In conclusion

Every year will offer some insect pest challenges and 2023 is no different. I expect to see higher levels of animal foraging for chafers on last year’s drought stressed weak turf, but lower levels of leatherjacket damage than previous years where timely Acelepryn applications were made.

We are also at the mercy of the British weather and find ourselves praying for a mild spring to support our turf in its battle against these insect pressures.

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