As we finally head into spring, Bayer recommends that Greenkeepers act now to safeguard against
potential Chafer Grub infestations.
Article taken from Greenkeeping.
“Chafer grubs have the potential to cause serious damage to turf playing surfaces and present a
tough repair challenge,” says Bayer’s Technical Manager, Dr. Colin Mumford. “Due to last year’s
issues with neonicotinoids and the subsequent two year suspension of products containing certain
actives (i.e. Clothianidin, Imidacloprid or Thiamethoxam), greenkeepers are uncertain about which
insecticides they are still permitted to use,” he explains.
“To put it simply,” says Colin, “the use of the neonicotinoid Imidacloprid on managed amenity and
sports turf isn''t affected because managed turfgrass is non-flowering.” Our message is therefore
simple; any Imidacloprid-containing product that has an approval for use on managed amenity and
sports turf is still fine for professional use.”
“Merit® Turf is an essential weapon for turf managers in the fight against Leatherjackets and Chafer
grubs and maintains its approval for use on managed amenity and sports turf,” says Colin.
“Chafer grubs are a real concern as they can cause an unstable surface that is potentially dangerous
for sports players or horses as a result of slippage.” He explains that the adult insects burrow into
the turf and lay their eggs close to the soil surface before the grubs hatch and start feeding on the
“They essentially cut the roots off and kill the turf. In the most severe cases, the turf surface will
actually come away from the ground and peel off like a carpet being lifted.” He adds that any foxes,
badgers or birds living nearby will easily tear up the unstable turf to feed on the Chafer grubs. This
can cause catastrophic damage to the playing surface and may take an entire season to rectify.
When trying to combat these challenging pests, being able to understand the range of species and
their associated lifecycles is essential. “There are four common species in the UK,” notes Colin. “The
Cockchafer is the largest but occurs more sporadically. The most damaging species are the Garden,
Welsh and Summer Chafers.”
He adds that the Cockchafer can take up to five years to go through one lifecycle whilst the Garden
Chafer completes its lifecycle in one year and the Welsh and Summer Chafer have a two year
“Without scientific examination, it is very difficult to tell the Welsh and Garden Chafer apart. If there
is a high risk of Chafer infestation, it is strongly advised that turf professionals use an insecticide like
Merit® Turf, every year - especially if the Chafer grub species is unknown.”
Colin explains the possibility of multiple stages of a grubs’ lifecycle presents a key challenge.
“Typically, some eggs will have been laid during the spring of the previous year but will be present
alongside larger grubs who hatched two years previously. Insecticide treatments won’t control these
larger grubs, effectively grubs in their 3rd instar (development stage). In fact by the time the grubs
have reached this size the damage will have been done.”
He advises that the most effective control is to apply an insecticide treatment like Bayer’s Merit®
Turf preventatively, when the beetles are laying their eggs. This tends to be in late spring and can be
anytime between the end of April through to July. “A turf professional will need to apply an
insecticide at this time of year, every year as not all grubs will die with just one application,” says
According to Colin, turf professionals often don’t realise that they have a problem and it is not until
they see damage to the turf that they become aware of it. At that point it’s often too late to achieve
any meaningful control until the following year.
Comments from Colin Robinson
Whilst frequency of treatment is a key issue, Colin Robinson of Kings Lynn Golf Club adds that
application technique is also important. “Merit® Turf needs to be applied evenly across the whole
turf area before thoroughly irrigating the treated turf. Watering-in is critical for successful control
and to move the active ingredient through the thatch and into the root zone of the turf. Merit®
Turf’s systemic mode of action means that when the grubs eat the roots, they subsequently stop
feeding before dying. The young grubs are also controlled through coming into contact with the
product in the soil.”
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