Nutrient Essentials: Boron

Interveinal chlorosis is typical of boron deficiency.

Canola needs a little bit of boron, and most Canadian Prairie soils have enough to meet this demand. A rain event that increases boron flow through the soil can alleviate most boron deficiencies. If boron deficiency occurs, it is more likely in sandy soils with low organic matter or in high pH soils. Soil pH above 8 will reduce boron solubility.

As boron is not (or, very weakly) mobile within the plant, look for deficiency symptoms on the newest growth.

Boron deficiencies look like:

—Interveinal chlorosis. Veins are green but the rest of the leaf is light green. (See the photo above.)
—New leaves are stunted and may roll up along the length of the leaves around the mid vein.
—Short, stunted root hairs and poor rooting.
—Long and unproductive flowering period. Boron is involved in pollen tube fertilization, and with boron deficiency, pods may not form. The plant keeps flowering and flowering producing new bud clusters from leaf axils, trying to get fertilization and pod set to occur.

Boron as a rescue product. One Ontario study showed that a foliar boron application may improve flower retention in hot conditions, but an economic benefit from this application on the Prairies is probably not likely.

Boron does not work to prevent clubroot. Boron has also been pitched as a way to control lygus bugs in canola. Boric acid is an ingredient in some household insect killers, but on a field scale there is no scientific evidence to say whether boron applications are effective or economic. Plus, unregistered products should not be applied as they can compromise canola marketing.

Source: Alberta Canola Producers Commission