I do pretty much what paintguy said. (We have a cedar fence stained in semi-solid that gets mold under the shaded horizontal supports, and a solid white stained picket that will get some green>black mildew/mold on the shady side). Sometimes bleach water is enough, sometimes I combine Soilax + bleach (it's no longer available so am using last of my stash, will have to look into Jomax). Don't get too close to the wood with the pressure washer, you can send splinters of wood flying off. I twist the nozzle for fan spray rather than jet stream also. Our white fence will need done this year and I have a can of Cabot's solid white stain on hand. Have never used their solid but was really pleased with the Cabot semi cedar tone on the privacy fence. The original white I used was an Olympic stain I got from an independent paint store (not big box). It held up pretty well for 14 years, no yellowing or anything. Exterior solid stains have probably made a lot of progress since then, tho, so there could be some better choices out there. I can tell you in recent years I used Behr stain on rental decks, complete waste of time and $ for me. That stuff was fading/pulling off by end of summer (I applied in spring). Not just in walk paths, either, but surfaces hit most by sun, or railing where hands occasionally rubbed. Did all the proper prep, too. Google and you'll see complaints on their stain (I checked too late, after the fact when I noticed the problems.) On our old deck I had good success with REZ solid stain, but primed with their oil-based primer first, then stained (per paint store instructions).

In my opinion one of the best ways to preserve a treated pine fence (especially posts that are buried) is with sump oil. Or you can use linseed oil. The people on one side of me did not want me to soak their posts in sump oil in order for it to soak into the timber. In fact they called me a nutcase for sugesting it would extend the life of them. For the record the posts are (hardwood) Australian redgum. Pailings are 13mm teated pine and the rails are 50x75mm treated pine. On the other side, where i have native bushland I did soak the base of the post in sump oil for just over 48 hours before putting them in the ground. I then sprayed the fence with sump oil. The untreated (much more wind protected) fence ended up with 4 posts snapped off at groung level they were rotten. There were pailings blown off etc etc. The fence on the other side off my home (which copped the FULL force of the wind is still nice and straight and still in good order. I still can't even wobble ANY post one bit. Both fences were put up together 17 years ago when we built. Another thing sump oil does is prevent termite attack. (If the buried part is soaked for 24-48 hrs before cementing them in). don't think that "treated" pine, or any other 'treated' timber will stop termites the chemicals leach out over time. Now the people next door want me to pay 1/2 for a new fence. I took them over showed them the other fence that was oiled and asked can you see any problem here. The grass is growing, as are all the plants there is no issues there. It's not as if i just poored oil all around the posts so the impact on the enviroment is infenticimal if at all. very little (if any) oil leaches out if they are soaked) the timber holds the oil inside it. If you don't want sump oil on your pailings then liseed oil is the next best thing. It is moisture that rots the timber(creates the enviroment for rottting) oils will repel the water keeping the as dry as posible and thus extending the life. And preventing yet more trees from being chopped down to cut into posts, rails and pailings. In fairness I said to those people next door if you buy all the materials I will help you put it up. But I am not paying 1/2 the cost for a fencing contractor to build another fence simply because you refused to take WELL KNOWN advice and called me a nut case in the process. Why should I fork out $2,864.00 (that's my half) simply because you chose not to listen to good old fashioned and well known advice. When I asked if he was prepared to pay half for the damage to my new garden bed, plants, shrubs and some other things I had stored where the fence fell on it all and brokes new shrubs etc he said "oh that's not my fault" "Can't you claim it on your insurance?" When asked why he isn't claiming his fence repairs on his insurance he said "Oh I don't have insurance". I said what happens if your house burns down how can you afford to pay the mortgage as well as the cost of living elsewhere. "Oh it won't burn down" was the answer I got. GO FIGURE.

Looking at the images I don’t think there is any need to pressure wash the fence. You can just clean the dust on the fence and start staining it. You can add multiple coats of stain as per the requirement. Hope this helps you.

go with ready seal