Lack of Pollination due to timing difference between bloom and lack of bees activitie

One of the reason for lack of fruit set in cold climates (such as Zone 5) is belived to be the timing delay betwen fruit plants bloom start and the start of activities by bees etc. Sometimes the plants start blooming early when the bugs and bees are still not active yet because of cold which causes lack of pollination.
My question is if it is possible to delay the bloom of the fruit trees by heavy mulching (6+ inches thick) over a circle with 1.5 ft radius around the tree (or more needed)?
I am asking this because here in Ottawa when the snow melts in spring, I can still see snow pile under a thin pile of leaves left in the lawn so I thought that a 6" thick leaves mulch should keep the ground around the tree frozen. Or is it mainly the sun shining on the plant wood that causes the leaves to sprout and the bloom to start.
What are other ways to delay the bloom without causing harm to the fruit trees?

 

Re: Lack of Pollination due to timing difference between bloom and lack of bees activ

If it is triggered by something other than temperature it wouldn't be affected by temperature. Elsewhere I once remarked on an ornamental Prunus being in flower at the same time in a foothill site, with snow around as in the lowlands and was told that kind was photoperiodic. Perhaps some or all early-blooming orchard cultivars of stone fruits are also.