Boron Deficiency in Root and Tuber Crops

Boron deficiency in carrots

In the field, boron deficiency typically causes a superficial pinhead-sized discoloration just under the skin of the carrot. The grayish irregularly shaped areas are ordinarily only seen after steam peeling of the carrots and are usually removed by normal domestic peeling. Severe boron deficiency causes further symptoms to develop. The tap roots frequently split and are often brittle. Leaves may ultimately be affected, turning a red or yellow color and later, just before the growing point dies, very small leaves are formed.

Typical recommended ranges for boron boradcast soil application for carrots is 1-2 lbs of B/acre. Normal plant analysis levels for the best quality and marketability have leaf boron levels in the 25-70 ppm range.*


*Always consult local crop advisors to check the proper dose rates. Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue analyses.

Boron deficiency in cassava

When cassava are boron deficient, plants are typically short because of reduced internodes. Young leaves are normally dark green, small and deformed, and carried on short petioles. Lower mature leaves may be flecked with grey, brown, or purple spots near the tip and margins. Resin may exude from lesions on petioles. Root growth is suppressed. Ultimately the growing point dies.

Boron deficiency in fodder beet

Boron deficiency in fodder beets characteristically causes the death of the growing point and the development of a black heart rot. Before the deficiency has reached this stage, the leaves, which may have cracked petioles, will have become progressively smaller and somewhat misshapen. After the death of the growing point, small bunches of leaves develop in the older leaf axils and the crown is very liable to become hollow and rot.

Boron deficiency in Japanese radish

In Japanese radish, boron deficiency causes the root to develop a black/brown discoloration that runs from the leaves down the core of the root.

Boron deficiency in mangold

Root and leaf symptoms of boron deficiency in mangold are very similar to those described for sugar beet, although the cracking of the epidermis on the midribs is possibly more common on mangold than on sugar beet.

Apart from the characteristic heart rot, death and blackening of the younger leaves, scabs, and galls may be found on the petioles of boron deficient mangold.

Boron deficiency in parsnips

When parsnip plants are boron deficient, the young leaves are small and die off while the older leaves show a marginal yellowing followed by a brown scorch. The petioles, which are thick and stiff, may crack and bend over.

Typical recommended ranges for boron boradcast soil application for parsnips is 2-3 lbs of B/acre. Normal plant analysis levels for the best quality and marketability have leaf boron levels in the 25-70 ppm range.*


*Always consult local crop advisors to check the proper dose rates. Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue analyses.

Boron deficiency in potatoes

Boron is essential for the health and quality of potatoes. The potato cooking quality may be compromised when the tubers have a boron deficiency. Fertilizing potatoes with adequate boron is necessary for:

• Movement of calcium throughout the plant for correct calcium nutrition
• Uniformity of cell type
• Increased vitamin C concentration, which boosts nutrition
• Yield and overall quality

Symptoms of boron deficiency in potatoes are seldom seen on the shoot, although reduced growth with short internodes and curled leaves have been reported. Symptoms are more readily seen in the tubers in the form of brown necrotic patches. The condition known as “internal rust spot” is responsive to application of boron fertilizers, but it is yet to be proven whether it's due to boron deficiency or only an indirect association with boron.

Reducing boron deficiency

Soil sampling and potato petiole and leaf analysis are crucial to determining if your potatoes are receiving adequate boron.

If boron fertilizers are applied in the first 14-30 days after tuber initiation, when potato cells are just beginning to divide, there is better uniformity of cell type.

Your boron fertilizer options

These fertilizers work best for potatoes:

• Granubor^® is an ideal material for dry-blend fertilizers applied broadcast preplant or surface banded
• Fertibor^® works best in fertilizer suspensions for preplant broadcast or band sprayed over the row
• Solubor^® allows you the most flexibility for applying boron fertilizer. It can be dissolved alone in water or in liquid fertilizers and/or pesticides, then applied to the soil or directly onto the foliage*
• Solubor has been found most effective when used as a foliar spray, 40 to 60 days after planting

Typical recommended ranges for boron boradcast soil application for potatoes is 0.5-1 lbs of B/acre. Normal plant analysis levels for the best quality and marketability have leaf boron levels in the 20-40 ppm range.**

Using boron fertilizers on potatoes helps growers improve the quality of the crop—and their ROI.


* Foliar sprays should not exceed 0.5 lb/acre boron per application.
**Always consult local crop advisors to check the proper dose rates. Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue analyses.

Boron deficiency in red or garden beets

Boron deficiency causes the development of internal black spots. Necrotic areas occur at random in the root or at the surface where disease organisms may enter causing a canker to develop. The necrotic areas render the beet unsuitable for canning. The growing point may die and multiple crowns develop.

Typical recommended ranges for boron boradcast soil application for beets is 2-3 lbs of B/acre. Normal plant analysis levels for the best quality and marketability have leaf boron levels in the 30-70 ppm range.*


*Always consult local crop advisors to check the proper dose rates. Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue analyses.

Boron deficiency in rutabaga

When rutabaga is boron deficient, brown, water-soaked areas develop in the root, normally in the outer regions of the xylem. These symptoms give rise to the various names for boron deficiency such as “brown heart,” “water core,” and “Raan.” In severe cases, the central tissue may break down and the root become hollow. The feeding value is reduced and the roots are likely to be tough, fibrous, and bitter. Keeping quality is poor and affected roots lose weight through loss of moisture in storage.

Normally no symptoms are seen on the leaves. The roots will be of normal size and the problem is only apparent after harvest.

Typical recommended ranges for boron boradcast soil application for rutabaga is 2-3 lbs of B/acre. Normal plant analysis levels for the best quality and marketability have leaf boron levels in the 25-60 ppm range.*


*Always consult local crop advisors to check the proper dose rates. Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue analyses.

Boron deficiency in sugar beets

Boron deficiency in sugar beets characteristically causes the death of the growing point and the development of a black heart rot. Before the deficiency has reached this stage, the leaves, which may have cracked petioles, will have become progressively smaller and somewhat misshapen. After the death of the growing point, small bunches of leaves develop in the older leaf axils and the crown is very liable to become hollow and rot.

Boron deficiency in swede

When swedes are boron deficient, brown, water-soaked areas develop in the root, normally in the outer regions of the xylem. These symptoms give rise to the various names for boron deficiency such as “brown heart,” “water core,” and “Raan."

In severe cases, the central tissue may break down and the root becomes hollow. The feeding value is reduced and the roots are likely to be tough, fibrous, and bitter. Keeping quality is poor and affected roots lose weight through loss of moisture in storage.

Normally no symptoms are seen on the leaves. The roots will be of normal size and the problem is only apparent after harvest.

Boron deficiency in sweet potatoes

Brown necrotic areas are found in the flesh of the root, particularly near the cambium around the periphery of the root when sweet potato is boron deficient. The flesh and roots are misshapen and the skin is rough and leathery in texture. Severely affected roots show surface cankers and splits covered with a hardened and blackened exudate. Boron deficiency symptoms usually appear in the latter part of the season. The terminal growth of the vines is restricted and the internodes are shortened.

As the deficiency becomes more severe, the petioles are curled and twisted, and the growing points may die. Premature abscission of leaves also occurs.

Typical recommended ranges for boron boradcast soil application for sweet potatoes is 0.5-1 lbs of B/acre. Normal plant analysis levels for the best quality and marketability have leaf boron levels in the 20-40 ppm range.*

*Always consult local crop advisors to check the proper dose rates. Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue analyses.

Boron deficiency in turnips

When turnips are boron deficient, brown, water-soaked areas develop in the root, normally in the outer regions of the xylem. These symptoms give rise to the various names for the deficiency such as “brown heart,” “water core,” and “Raan." In severe cases, the central tissue may break down and the root becomes hollow. Reduced feeding value and roots that are likely to be tough, fibrous, and bitter is common. Keeping quality is poor and affected roots lose weight through loss of moisture in storage.

Normally, leaves have no visible symptoms. The roots will be normal size and the problem is only apparent after harvest.

Typical recommended ranges for boron boradcast soil application for turnips is 2-3 lbs of B/acre. Normal plant analysis levels for the best quality and marketability have leaf boron levels in the 25-60 ppm range.*


*Always consult local crop advisors to check the proper dose rates. Rates of boron fertilization should be based on yield goals along with soil tests and/or plant tissue analyses.