Chafer dig

The notion of a trial against chafer grubs in a real life turf situation, is as appealing as it is difficult to realise.

Leatherjacket trials are challenging, but there are ways to bring them to the surface to assess activity at least, with chafers its dig or keep guessing.

And for some unknown reason most turf managers insist that I don’t dig up huge swathes of fairway looking for grubs.

In my old life I’ve dug up chafer grubs for lab trials down as deep as 10 inches, where it’s the middle of summer and they’re pushing down to avoid drying out, but luckily with all this seasons rain, the one benefit was the grubs were near the surface for the dig.

All found in the top one – two inches from the surface.

 

The trial

Simple enough trial design.

Aim = Compare three treatments control of chafer grub activity.

Treatments:

1. Untreated – no products applied
2. Acelepryn SOLO (sprayed late July 2023)
3. Acelepryn + Nematrident B & Nemaspreader (same timing on the Acelepryn, then the Nematodes sprayed 3rd August 2023)

Areas of damage from the chafers were identified and sprayed as per my beautiful painting below.

So untreated areas were not treated, areas 2 & 3 were sprayed the same day and area 3 was then over sprayed 7-14 days later with the Nematrident B.

 

Then its just twiddle thumbs and wait for spring time.

We then took 15 samples from each treatment area, using a turf doctor to cut, and we manually broke apart the samples in search of the grubs.

Collected grubs were sorted by size and the samples were replaced. Repeat that process 135 times, without your diggers storming off and you’re all done!

 

We had a good mix of very small first instar grubs, can barely be seen in the cups.

Medium 2nd or 3rd instars (depending on species)

Large grubs from the fairways were mainly Welsh chafers, but in one specific area under some trees with lower traffic some monster XL grubs, cockchafers, as too large to be another species.

I’ve got some number crunching to enter all the data and graph it up, but on the ground it looked good for the treatments over the untreated areas, Acelepryn is a very good product on chafer grubs but as we will always have a mixed cohort population in the ground it’s always going to need to be a programmed approach.

Was great to see the Nematrident B + Nemaspreader give uplift in efficacy in a tough situation.

Thanks very much to the dig team who helped out; course manager for allowing us to dig and getting stuck in, Craig Lalley for putting the whole thing together, Tom Wood – highest count in a single sample (13), Dylan Gibson & Eric Chen from our biologicals team also.

For more info on chafers see this blog from last year here.