Nutrient deficiencies of Bracteantha bracteata 'Florabella Pink'

By James L. Gibson, Brian E. Whipker, Paul V. Nelson, John M. Dole, Amy Williams, Brenda R. Cleveland and F.R. Walls

Fertility monitoring and management for Bracteantha bracteata requires a balancing of the plant's needs. Growers must be aware and manage the root substrate pH, electrical conductivity (EC) and provide adequate, but not excessive, levels of all essential elements.

Nutrient deficiency descriptions are unavailable for most floriculture crops, yet growers must often make quick diagnoses. A research project initiated at North Carolina State University in Raleigh documented deficiency symptoms in vegetatively propagated Bracteantha bracteata 'Florabella Pink' to assist growers. Using a plant diagnostic lab to identify the source of problems is still the best way to ensure accurate diagnoses, since many nutritional, physiological, insect and disease problems can mimic each other.

Disclainer: Growers should read and follow all label directions. Test the corrective procedure on a small number of plants prior to applying it to the entire crop.

Macronutrients · Micronutrients

Macronutrients
Photograph

Description

Possible Causes and Management
Nitrogen (N) (top)
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Initially, nitrogen-deficient plants are smaller and light green when compared to the control.

Low Substrate Nitrogen
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As symptoms progress, the lowest oldest leaves turn chlorotic.

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Advanced symptoms include small stunted plants with uniformly chlorotic lower mature leaves, which eventually abscise.

Phosphorus (P) (top)
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Phosphorus deficiency is observed as pale green plants that are relatively similar in size to the control.

Low Substrate Phosphorus
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The lower mature leaves have a faint chlorosis, followed by the tips developing a brown necrosis.

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Under advanced symptoms, brown necrotic patches affect the recently mature and mature leaves. Complete necrosis develops with the papery textured mature leaves withering.

Potassium (K) (top)
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Initially, potassium deficiency is observed as a yellowing of the lower mature leaves, which begins at the leaf tips and margins.

Low Substrate Potassium
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As symptoms progress, the chlorosis on the mature leaves becomes more pronounced. The chlorotic regions then develop a brown papery necrotic area on the margins. The upper and lower mature leaves become cupped with a downward curl.

Calcium (Ca) (top)
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Initial calcium-deficiency symptoms develop as small brown spots on the young and recently mature leaves, starting at the base and progressing to the middle of the leaf. The young leaves appear small and deformed.

Low Substrate Calcium
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Small brown to black spots begin to develop, moving from the base of the midrib to the tip of the recently mature and mature leaves. The necrosis also moves into adjoining veins.

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With advanced calcium deficiency symptoms, flower buds are incomplete and turn necrotic.

Magnesium (Mg) (top)
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Magnesium deficient plants begin as a interveinal chlorosis on the recently mature and mature leaves and the margins turn light green.

Low Substrate Magnesium
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As symptoms progress, a distinct chlorosis appears on the recently mature and mature leaves. The margins are yellowing while the midrib remains dark green.

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Advanced symptoms appear as a severe yellow interveinal chlorosis, which is accompanied by brown necrotic margins and tips.

Sulfur (S) (top)
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Initially sulfur deficiency appear with the growing point turning to a lime-green color compared to the control. The young leaves are often smaller than the control.

Low Substrate Sulfur
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As symptoms progress, an intense lime green chlorosis affects the young and recently mature leaves progressing from the leaf base to the tip. The mature leaves remain a dark green.

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Overall stunting of the plant occurs with advanced sulfur deficiency. The plants become thin and spindly with smaller leaves and flowers become slightly bleached, compared to the control.

Micronutrients (top)
Photograph

Description

Possible Causes and Management
Boron (B) (top)
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Initially, boron-deficient plants are stunted and compact.

Low Substrate Boron
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As symptoms progress, the terminal tip stops growing, forming a rosette appearance and subsequently flower buds cease to develop. The young and recently mature leaves become small and deformed, while a brown necrosis starts at the leaf base. The petioles of the young to mature leaves expand in width and are bleached.

Copper (Cu) (top)
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Copper-deficient plants show initial symptoms with light green young and recently mature leaves compared to the control.

Low Substrate Copper
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Mature leaves form patches of slightly brown transparent spots.

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Advanced symptoms develop a basal necrosis on the margins of mature leaves.

Iron (Fe) (top)
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Initially, iron-deficient young leaves are light green compared to the control.

Low Substrate Iron
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As symptoms develop, chlorosis progresses to the recently mature leaves, while the mature leaves remain dark green. The light green chlorosis is progresses into a yellowish-green color.

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At advanced symptoms the young leaves are yellowish-white and the recently mature leaves are light yellow.

Manganese (Mn) (top)
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Manganese deficiency begins with the young to recently mature leaves turning light green with slightly swollen or wider leaf blades than the control.

Low Substrate Manganese
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As symptoms progress, the mature leaves form small brown transparent spots in the middle portion of the leaf. The leaves appear more swollen and lighter green.

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Leaf comparison of manganese-deficient leaves to the control.

Zinc (Zn) (top)
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Initially zinc-deficient plants are a lighter green than the control.

Low Substrate Zinc
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As symptoms progress the leaf tips develop a faint brownish-gray necrosis.

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Advanced symptoms include smaller plants with mature leaf tips having a papery tan necrosis, which progresses to the base.

Amy L. Williams, Dharmalingam S. Pitchay and James L. Gibson are graduate research assistants, Paul V. Nelson is professor in floriculture, John Dole is associate professor in floriculture, and Brian E. Whipker is assistant professor in floriculture at North Carolina State University, Department of Horticultural Science, Box 7609, Raleigh, NC 27695-7609. Brenda R. Cleveland is agronomist and F.R. Walls is assistant director, Agronomic Division of North Carolina Department of Agriculture. The authors thank Paul Ecke Ranch, Encinitas, Calif., Tom Abramowski, Rockwell Farms, Rockwell, N.C., and the North Carolina Commercial Flower Growers' for grant support, Paul Ecke Ranch for supplying the vegetative cuttings and Smithers-Oasis for supplying the propagation medium. The images and corrective procedures can be viewed at http://www.ces.ncsu.edu/floriculture.

Disclainer: Growers should read and follow all label directions. Test the corrective procedure on a small number of plants prior to applying it to the entire crop.

© Copyright NC State University, 2002

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