Boron

Boron plays an important role in the structure of cell walls, fruit set and seed development. It is also a component of protein and carbohydrate metabolism. Boron deficiency symptoms vary widely between crops as seen in the table below:

Crop	Boron Deficiency Symptoms
Rutabaga, turnips	Brown, watery areas or hollow centres in roots
Celery	Cracked stems, brown cat scratches, blackened hearts
Brassica/cole crops	Hollow stems; brown curds, deformed buds
Sugar beets, table beets, spinach	Yellowing of leaves; spotting, cracking of root
Apples	Small, flattened or misshapen fruit; low seed count; internal corking, cracking and russetting; dead terminal buds

Boron toxicity may occur when sensitive crops are planted in a rotation where boron has been applied (or over applied). The toxicity symptoms include spot like, striped or blotchy yellowing on the leaves. This leads to the death of the tissue, usually beginning at the leaf tips and margins of older leaves. Under severe conditions, this will eventually develop over the whole plant.

There is no OMAFRA-accredited soil boron test. Some soil tests will report a soil boron value. Soil levels are often less than 1 ppm making it very difficult to get an accurate measurement.

Some crops are very sensitive to boron, even at low levels. Consider the boron sensitivity of all rotational crops when applying boron. A soil pH between 5.0 and 7.0 provides the best conditions for boron uptake.

Boron deficiencies are more likely to occur on soils with low organic matter, and on exposed or eroded subsoils. Also, Boron availability decreases during periods of drought.