Chafer Grub

Chafer Grub

A chafer grub infestation can quickly transform a prestige lawn or an area of prized turf into a ploughed field.

Key Facts:

  • Common names: Chafer grubs, mainly garden chafer and welsh chafer
  • Scientific names: Phyllopertha horticolaand Hoplia philanthus
  • Plants affected: Lawns & Turf
  • Main symptoms: Scruffy turf with pieces pulled up by birds and animals searching for the grubs
  • Most active: Grubs: September-April; Adult beetles: May-June

Chafer Stages

Have you got a chafer beetle problem?

The grubs live in the soil, emerging from eggs laid in July to feed on the roots of grass during late Summer/Autumn. They then reappear in Spring to continue feeding until emerging as fully grown chafer beetles or chafer bugs in mId May - June. Further damage to lawns is caused by crows, foxes and badgers who tear up the grass to look for these grubs during the months when the grubs are active.

What are they?

Chafer Grubs: These are young maggot-like larvae before they hatch into chafer beetles. Chafer beetles are commonly one of two types: the Garden Chafer and Cockchafer. The Garden Chafer has an annual lifecycle whereas the Cockchafer is larger and more destructive because it lives in the soil for 3 years, eating roots, before it hatches. They live near the soil surface and will only burrow deeper once autumn temperatures start to drop.

It is crucial that the correct species of chafer is identified as this can affect the best timing of control using nematodes. We would be pleased to help with identification if required. Please email high quality images of adults or grub stages to info@progreen.co.uk

Control:

Chemical control measures such as Merit Turf have now disappeared but fear not as there are very effective biological pest control products on the market based on microscopic worms or nematodes which go out and actively hunt down chafer grub larvae. These nematodes are carriers of bacteria which are harmful to the chafer grub larva. There are pack sizes suitable to both amateur and professional growers. These natural non-pesticide alternatives are completely safe to humans and pets with no exclusion period after application.

Nematrident CT Plus (cooler soil temperatures) or Nematrident C (warmer soil temperatures) for Chafer grub control.

NemaTrident C & NemaTrident CT Plus are uniquely supplied as twin-pack solutions containing the naturally occurring insect parasitic nematode together with the Nemaspreader soil conditioner which typically gives a 20-30% advantage in performance over alternative products by allowing the nematodes to move more freely through the soil actively seeking the pest.
Both products can be applied by watering can, knapsack sprayer, Nemasprayer (hose end feeder) or boom sprayer. It’s available in packs to treat 100m2, 500m2 or 1000m2.

It is important that soil temperatures are high enough to support the use of these products and soil temperatures can be accurately measured by using a soil probe thermometer

These biological control agents need to be applied in high water volumes to moist soils to allow free movement of nematodes through the soil to where the chafer grubs are feeding. NemaTrident C & Nematrident CT Plus achieve excellent results if used correctly but treatment should be considered on an annual basis to ensure control of newly laid and older larvae.

Soils should be moist both before, during and after application of Nematrident products for effective results. Application applied during the rain are most effective and early morning or evening applications are preferred. Another top tip, is to allow the Nematodes top reach room temperature before application to avoid “shocking” the nematodes. High levels of thatch in the turf can also be detrimental by preventing nematodes entering the soil. Thatch levels can be reduced by standard cultural and physical methods and also helped by using products such as Amvista Thatch GO

The initial and ongoing risk of chafer damage can be monitored by using a Chafer beetle trap

These traps are useful in two ways. Firstly by directly reducing the number of eggs laid by the adult beetles. This can be significant, as each female adult can lay up to 50 eggs. Secondly, the catch counts will indicate the likely ongoing risk from autumn grub damage. Note, that egg laying can take place soon after the first adults flights. Chafer Traps should be set in position in the second – third week of May.

As an extra integrated control measure, there is now evidence that treating the affected lawn or turf with a slow release, nitrogen based fertiliser containing calcium cyanamide, aids recovery of chafer damaged lawns and turf by the metabolites damaging the chafer grub larvae such Amvista Chafer Special.

To summarise, nematodes should be viewed not as a “quick fix” replacement for previous synthetic chemical options, but rather as a vital component of an integrated solution which demand high levels of user care throughout and after their application. We are committed to providing this backup to our customers to achieve the best possible outcomes.

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