This is Mistletoe (Viscum album) growing on the trunk of the apple tree. NB It might be helpful to click on the photo to enlarge it to get a good look at it- we have entered the season of low raking sunlight and deep shadows.
 'Tis the season or fast approaching but Mistletoe has been associated with plant lore at least as long as its association with Christmas and probably further back than that.
 Strictly speaking it is a hemiparasite; it derives nutrition and water from the host tree but photosynthesis takes place as well. Then again this is probably not a point that people give much thought to when they're kissing under a few sprigs of it.