Built In Wall Unit - Part I

I'm starting to embark on my next project - a built in wall unit that will include multiple bookshelves, a section of small drawers and a base cabinet. The project will be built out of Southern Yellow Pine. Last Friday I took a drive to Fishersville with a U-Haul trailer and picked up about 450 board feet of 10" and wider southern yellow pine boards for a $1.17 a board foot. The wood is a bit of a mix. There are some really clear boards and some that have a lot of knots. The goal is to use the clear boards for the shelves and cabinet top. The less then clear boards will be used for some of the smaller parts, and narrow strips, working around the knots. Where we can't work around the knots and the knots are still tight, I plan on using those boards either as shelves inside the cabinet or on the dividers inside the cabinet.

Currently I have boards stacked all over the garage. I started planing some tonight. Overall its amazing the grain and the look of the boards. However, the boards seem to be taking a major toll on my planer blades. I want to at least rough plane the boards before switching blades.

There are two headaches that have shown up. In the image below, you can see a few light grey streaks in the planed lumber. They appear to be discoloration in the actual wood itself. These don't show on all boards and some are on only one face of a board.

The other headache involves the grain structure on these boards. Where the grain forms a "circle" the planer is having a very difficult time. I'm experiencing tear out on either one side or the other side of the "circles". Sometimes the tear out is very light and can be sanded out, others are quite deep. I've left the boards at a fairly thick size, figuring that the best way to deal with the tear out issue is to use new blades. By using the older blades it should get rid of the worst issues such as dirt and "candied" resin that I think is probably dulling the existing knives.