30 March 2026

HELP! Leatherjackets are destroying my new turf?

Q. We applied a box of nematodes about a week ago due to leatherjacket infestation in newly laid turf (weather has been warm and dry) and we are wondering if need 2nd application as the grubs are now like fat caterpillars in size? Please see pictures of a rapidly disappearing lawn. Should we water the lawn to keep damp if no rain comes after application? I also want to buy the lawn repair sticks and Root Success, but wanted to check how soon after nematode application can we sow these and if it needs watering in also after application?” Many thanks for your advice. Tricia

A. Thanks for the message and you have fat leatherjackets in newly laid turf? There is no point in applying Nemasys Leatherjacket Killer again after only a week as it will take 3 weeks for the nematodes to work. Water to stop the turf drying out (I suspect you are already doing this) and then if needed I would aim to treat again in 4 – 6 weeks and then again in the Autumn (Sept).

Use the Root Success to save the grass that’s left and yes sow the seed now. You can use Lawn Repair Sticks at anytime after application as they are not affected by the nematodes. You do have to keep them moist to germinate, so again if you are watering anyway it might be worth using them sooner rather than later. 

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