Boron Deficiency in Flowers and Ornamental Crops

When an areca palm is boron deficient, the older leaves show a mottled chlorosis starting at the tips. Narrow transverse chlorotic streaks develop interveinally and the streaks coalesce forming necrotic lesions. The youngest leaves and growing point eventually die.

In old palms, boron deficiency causes stunting with the stem tapering abruptly. Flowers and fruits are small and often die on stunted inflorescences.

Brown flecks, which become translucent, are the first signs of boron deficiency and are seen on the young expanding leaves. Leaves developing later are distorted and show necrotic patches round the margins. Apical growing points die back. 

The terminal buds and leaves show a rosette condition with a puckering of the tip leaves if begonias are boron deficient. The terminal buds and leaves later become necrotic. Growth is generally stunted. The bulb has corky patches or nodules.

A high incidence of calyx splitting is usually the first sign of boron deficiency. The leaves split at the nodes and the flower buds abort. Where buds do not abort there are few petals which dry off and the style is pronounced.

Red patches, which develop along the central veins on the lower leaves, later spread over the leaf and become necrotic. The leaves tend to be spoon shaped with serrated tips. The uppermost lateral shoots may have a “witch’s broom” appearance.

Both total bloom production and the yield of marketable blooms can be increased by boron application. Where boron supply is marginal, liming can markedly increase calyx splitting in the absence of a boron supply in the liquid feed or fertilizer.

In mild cases of boron deficiency, the petals fail to unroll properly and become “quilled." When the deficiency is severe, you will see symptoms in the leaves which are brittle and closely spaced. Some down-curling of the leaves may occur and leaf tips may become chlorotic. There may be some loss of flower color. When the boron deficiency is acute, the buds fail to open properly. Growing point death is followed by multiple shoot formation.

Boron deficiency in pyrethrum causes the development of misshapen and malformed flowers and apical dieback in pyrethrum. Ray florets may be reduced to one third their normal length. They have ragged tips and they may be formed on only part of the circumference. In some cases, ray florets may be completely absent.

Boron deficiency symptoms in geramiums include:

• Very brittle and puckered leaves
• Small lesions on young leaves that eventually form holes

The first symptoms of boron deficiency occur on the flowers, which are distorted and carry fewer petals. Pollen production is restricted and stigmas absent or poorly developed. Flowering stalks are short and may split.

Only expect leaf symptoms after you see symptoms on flowers and when the boron deficiency is more severe. Some chlorosis may occur and red/violet spots develop near the margin and tips of older leaves. Newer leaves are:

• Distorted
• Often cupped
• Wrinkled
• Much thicker than healthy leaves

The symptoms of boron deficiency in gladioli include:

• Cracked leaf margins (especially on the first leaves to emerge)
• Translucent streaks between the veins
• Hooked leaf tips
• Failure of the lower petals to expand normally

In addition, the flower petals are mottled and the flower stems may be hollow, lacking a normal pith.

Boron deficiency in India rubber plants causes a stunting and malformation of the small immature leaves together with a necrosis of the terminal growing point. Young leaves are liable to show transverse splits which exude latex.

When larkspur are boron deficient, they exhibit the following symptoms:

• Terminal growth ceases
• Leaves are chlorotic and die at the tips
• Stalks are short

Symptoms of boron deficiency in nasturtium include:

• Dark green growth of the terminal growing point
• Considerably reduced terminal growing point
• Leaves are small and distorted

The buds, particularly those near the tip, stop growing in boron deficient poinsettia. The young terminal leaves are thick and tend to roll. The midrib on the under side of the leaf may crack and the bracts, which develop slowly, are abnormal.

In boron deficient rose plants, the leaves are distorted and elongated with irregular serrations. The loss of apical dominance results in multiple branching of the flowering stems which are distorted. The petals may have serrated margins and show irregular pigmentation.

In cases of severe boron deficiency, necrosis of the growing points and flowering shoots may be expected.

Symptoms of boron deficiency in tulips include:

• Discolored petals, often with a central or marginal white patch
• Stunted and easily breakable flowers and stems
• Some browning in the bulbs