Wood treatment recommendations for slat fence?

[Fez111]

Hi All,
I've just had some screening/landscaping fence battens delivered and will be installing slat fencing.
what would you recommend as the best product to treat the wood with to preserve it before i install?, particularly to prevent/ slow it going silver?

Also, best to do this now before installed? or once on wall?

for context the wood is uc3 green treated battens 25x45 - 4.2m. ive got about 60m2 to do. i asked the yard where i bought the timber and they just said because its treated, no need to do anything, but i've seen it silver badly at a friends house who used the same wood for fencing about a year ago - hence teh question here.

Thanks in advance.

 

[Wayners]

I've always recommended leaving a year to weather in before treating or at least a few months of summer.
Maybe a clear primer preserver