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
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Macronutrients
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Photograph
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Possible Causes and Management
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| Nitrogen (N) (top) |
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Initially, nitrogen-deficient plants are smaller and light green
when compared to the control.
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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.
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| Phosphorus (P) (top) |
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Phosphorus deficiency is observed as pale green plants that are
relatively similar in size to the control.
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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.
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| 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.
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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.
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| 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.
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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.
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| 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.
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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.
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| 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.
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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.
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Micronutrients (top)
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Photograph
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|
Possible Causes and Management
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| Boron (B) (top)
|
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Initially, boron-deficient plants are stunted and compact.
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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.
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| 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.
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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.
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| Iron (Fe) (top)
|
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Initially, iron-deficient young leaves are light green compared
to the control.
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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.
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| 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.
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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.
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| Zinc (Zn) (top)
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Initially zinc-deficient plants are a lighter green than the control.
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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.
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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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