This may interest you 
Boron (B) Micronutrient and Immobile element
Boron is important when dealing with maturation, pollen germination and seed production. As well as keeping calcium in soluble forms and keeping the stems, stalks, branches strong. Born keeps good color on the leaves and helps produce the plants structure. Boron also aids in cell division and protein formation.
Boron deficiencies will show up first in younger leaves (they may turn yellow), then moves up the plant. Boron deficiency can resemble calcium deficiency. Stunting, discolouration, possible death of the growing tips, bud abortion and development. The Roots will show a stunted with swollen short secondary roots, leaves distorted, sometimes bronzed or scorched. Tip of the shoot dies; stems and petioles are brittle. Boron deficiency plants are easy to tell, because of the spotting the leaves show like a strawberry mark and or splashes of the marking. Boron-deficiency symptoms first appear at the growing points. They also can show signs of newer growths turning gray and or dying, bud deformed, curling of the leaves which are often spotted and discolored. Newer growths appear to look like they are burnt. They can show signs of hollow stems along with yellowish to brownish color leaves. Dead (Necrotic) spots develop between leaf veins, as well as the leaves becoming thick. The leaves will wilt with necrotic and chlorotic spotting. Boron is poorly absorbed with low potassium content. First signs of the deficiency are abnormal growth tips. Having not enough boron can also invite troubles for fungus problems from the internal tissues to rot away, as well as the root hairs along with them being discolored. To avoid having a Boron deficiency try to keep the ph below 7 and to improve the moisture as well as retaining light soils.
Too much boron in your plants can produce a lot of problems. The leave tips turn yellow progressing inwards causing the plant to soon die slowly along with leaves dropping a lot.
Can show same signs as if a magnesium deficiency, but only happens on newer growths. Parts affected by a boron deficiency are: Growing points and young leaves.
Problems with Boron Being Locked out by PH troubles
Soil ph under 5.5 or over 6.8, sandy soil, soil with low organic matter and or lack of nitrogen.
Soil
Boron gets locked out of soil growing at ph levels of 2.0-5.0
Boron is absorbed best in soil at a ph level of 5.0-7.0 (Wouldnt recommend having a soil ph of over 7.0 in soil) Anything out of the ranges listed will contribute to a Boron deficiency.
Hydro and Soil less Mediums
Boron gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-5.0
Boron is absorbed best in Hydro and Soil less Mediums at ph levels of 5.0-6.0(Wouldnt recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a boron deficiency.
Solution to fixing a Boron deficiency
One of the ways you can fix a boron deficiency is to either foliar spray or water regular. Treat with one teaspoon of Boric acid (sold as eyewash) per gallon of water. (Only mixing at ½ strength when using chemical nutrients or it will cause nutrient burn!) Other nutrients that have boron in them are: Borax, Boric Acid, Colemanite, Sodium pentaborate, Sodium tetraborate, which are ALL fast absorption. Garden Manure, Bone Meal are both good boron supplements, but are slow/medium absorption.
Now if you added to much chemical nutrients and or organics, (which is hard to burn your plants when using organics) you need to flush the soil with plain water. You need to use 2 times as much water as the size of the pot, for example: If you have a 5 gallon pot and need to flush it, you need to use 10 gallons of water to rinse out the soil good enough to get rid of excessive nutrients.
hope this helps
