I’ve looked a bit but have yet to do a deep dive in the Buzz archives so sorry if this has been gone over.
EAB is hitting pretty hard this year. We had a big set of Ash removals
to be major differences in the strength of different trees right next to each other. Enough to give me a little bit of pause while rigging and wonder if I may be getting carried away.
EAB is going to turn some trees real weak, real quickly. Using a minimim of 3 slings for any brushy pick would be my advice, along with each sling being long enough to tie a few marls along the stem before terminating. Is something breaks, the marls can help keep things together. Avoid wide interior angles of your slings, as this puts undue stress on the pick.
Another strategy is what i call a tell-tail. This is essentially a long sling hanging down through the COM. If you tie things off wrong, the tell-tail will be out of line. You can refer to it while setting the initial slings, and then, if desired, it can actually be terminated down low to help share the lift.
You’ll want to ensure the hook is centered with, but above the center of mass of the pick. If you’re climbing on the crane, ensure you haven’t influenced the hook away from the COM when tying off the first and second sling. If all is tied off and pretensioned properly, you should be able to cut straight through. If unsure, the most practical cut is a shelf cut (make a level cut beginning from the underside of the lean, and stop 3/4 to 7/8 through…finish with a vertical “chair back” that meets or crosses the apex of the first cut.
Take a smaller pick first. If the crane has an LMI, take note of the weight and use it as a guide for estimating the rest of the tree. When picking near capacity of the crane chart, you lose for estimating under the actual weight.
Think safety and don't take any shortcuts. If you have to adjust or make changes, do it!