The southeastern coastal plain is blessed with abundant rainfall, most places getting over 4 feet of rain annually. All that rain makes gardening much easier than in the arid west, but it also brings up the problem of micronutrients leaching away and leaving plants with deficiencies that need to be addressed.
Such is the case with boron, an element that is necessary in plant metabolism, with deficiencies showing up as poor fruit set in fruit crops. I planted some semi-dwarf plums, pears, apples, and persimmons in 2010, and have yet to have a real bumper crop that I can give away to friends and neighbors. Maybe it is because the trees are still small, but I have noticed that the abundance of blossoms in the spring does not translate to an abundance of fruit in the fall. So I have taken the advice of several agricultural extension programs and I am making a boron foliar spray part of my annual fruit tree program.
Well, not exactly a foliar spray. Nothing has leafed out yet, and blossoms are just forming, but you want to have the boron ready when the buds do open and the leaves start growing. If you want to be a stickler for terminology, you can call it a ramial spray, ramial being the Latin adjective to describe a tree branch.
I put about a gram of boric acid (available at most dollar stores as roach or ant poison) into 2 liters of manure tea or compost tea and then strain that into a hose sprayer attachment. Give all the bare branches a spray, and the ppms of boron will get a boost up to a healthy level. Boron is poorly transported through the plant's vascular system, probably because the way fruit trees evolved, boron was always transported through the air. If you have ever seen the wind howl out west and kick up dust from a dry lake bed (like the kind where boron is mined), you know what I mean by "transported through the air".
Unfortunately for those of us in the southeast, the closest dry lake bed is a couple thousand kilometers to the west, and any dust kicked up out there is going to settle out by the time the wind gets here. So we have to take over and give Nature a hand, at least if we want a nice crop of fruit from our trees.