Do I apply neem oil on top of mulch or directly on soil for curl grub infestation?

[KimF]

Hi I have discovered lots of curl grubs in a large garden bed in the backyard. It’s planted with natives that have started struggling (one died) and I discovered the grubs when I went to replace the dead banksia with new plants. There are so many- about 5 per shovel of dirt! 
I bought Neem oil to treat.. but I’ve recently laid around 8cm of wood chip mulch on the bed - do I need to move the mulch and treat the whole bed with neem oil? 

[MitchellMc]

Welcome to the Bunnings Workshop community @KimF. It's sensational to have you join us, and many thanks for your question about applying neem oil.

Ideally it would be best to apply directly to the soil, but you can apply over the mulch. Obviously, some of your solution will be absorbed by the mulch, so you'd need to account for that and make sure the soil becomes saturated after it passes through the mulch. Just give the area a good drenching with a watering can.

Please let me know if you have any questions.

Mitchell