Yes I used a new clean 5 litre Kill a spray type sprayer ( £6 ish in Wilkisons ) used tepid water and sprayed in a period when the soil was a degree oC above above the minimum temp required for success .As the nemtode control is in effect microscopic worms they can easily be sprayed in a coarse sprey jet. .
When I did mine last year I put the new sprayer onto coarse spray instead of fine mist and filled it to the dose line . Took out some water into a plastic jug , then made up the nematodes in the jug , once well dissapaited in the water in the jug , poured the contents in to the sprayer and put the pump into it , then gently shook the contents for 30 seconds or so and gave it ten pumps to get the sprayer pressure up .
Once on the beds I add a few more pumps and had to adjust the spray to get a better coarse spray pattern then went and sprayed all the beds ..it is apparently best to get it on the ground instead of the leaves but splashes on the leaves won't hurt anything as the nematodes are a natural earth borne predator 9 we just use them in concentrated form that is quite harmless to humans and animals etc.inc insects , birds and amphibians .
Once the solution has soaked into the soil it starts working and god help any slug or45 snail it comes across. The nematodes eat into the slugs , this kills kill them and they continue to eat the dead slug .. at the same time laying new nematode eggs if the temprature and moisture levels are good enugh .
So long as the temperature stays high enough and there is no cold rain it will remain working for a long while some thing like four months apparently .
You use top up sprays to get the dormant slug eggs that eventually hatch and also to catch any incoming slugs that come after the initial spray. Especialy a late treatment to reduce any overwintering slug and snail polulation .
I sprayed twice last year and so far have only found evidence of a few slugs this year . I've used up my old slug pellet and will soon be back on the nematode stuff. In mid July
Note the paste in which the nematodes comes has a fridge shelf life of around a month once opened if cling filmed straight afgter taking out the dose your going to use .
So you could easily take your time over a couple of days to do several beds once the sealed pack is opened. or do two or more sprayings on one or two smaller beds.
Do use a new clean sprayer , for a sprayer that's had insecticide in it may well kill the nematodes even from the faintest of insecticide contaminations dissolved into the plastic body of a sprayer .