Was going to stain fence...but pickets have white green blobs? (fences, sealer)

[peet111]

I went out to stain my newish fence today so just to check absorbency, I squirted water on a few boards and the water was sucked right in. It's been out a month. But when I stained the first one all of this greenish blobs cover about 50% of the board and are definitely repelling the stain. You can even seen the green through as it is semi-transparent. I was in the shade so initially didn't notice. So I stopped. I test sanded on another board and the green waxy substance turns white but doesn't seem likely to come off unless done with a machine. And I've never read anywhere about people needing to sand fences. But I'm a newbie on this.

I don't feel I can wait as some of the boards are already trying to warp but at least 50% of the boards of 60 feet have this.
I searched everywhere and I can't seem to find the answer. Any suggestions?
I realize it is probably chemicals or wax but how do I fix it?

[LIcenter]

Sounds like dried sap. You might have to prime, and then go with a solid stain. Just a guess, as you have no photos posted.

[TrapperL]

If the fence is already up, staining will all but destroy the wood. The issue is you can't stain the 4 sides, top and bottom. You can usually only stain one side, sometimes both sides but you can't stain the bottom. I can assure you that the pickets will get so incredibly crooked that you'll think you've been robbed. The problem is when it rains, the wood will absorb the water. But it can only get out on the parts that did not get stained. This causes uneven drying and the warpage.

[K'ledgeBldr]

Pressure-treated dog-eared pickets are usually cut from "sapwood". By your description it sounds like you got some that have high levels of sap- the green is the preservative.

Not really a lot you can do about it- but the darker the stain/sealer, the less likely you are to notice.