To grow shitake on fruit woods you must keep the logs wet. The best method I've found is to soak the new logs, submerged in a barrel for a few days prior to inoculation.
If they dry out at all while the hyphae are growing and spreading they are in danger of not being able to spread.
Shitake hyphae (as almost all fungi hyphae grow in the cambium layers first, then they will migrate into the heart wood (the dense part of any tree).
Usually the first bloom of fruits occur when the cambium is full of hyphae, the second bloom will happen while they are moving into the heart wood.
Since it is the cambium we want full of hyphae, keeping the logs wet will speed up this process.
It is when a fruit logs cambium starts to dry that causes most failures when using these for mushroom growing medium.
Chips are always better than whole logs since it is easier to control moisture content, inoculation, as well as contamination.
This holds true for all wood species that you can use for producing mushrooms.
By wet I mean damp
enough to wick
water into a paper towel laid on the end grain, not as in dripping off the log all the time.
A mister setup along with a timer is the easiest way to keep any logs at the just right moisture content.
Redhawk