Nutrient Deficiencies of Vegetative
Strawflower Bracteantha bracteata 'Matilda Yellow'
Amy L. Williams, James L. Gibson, Brian E. Whipker, Paul V. Nelson, John
M. Dole, F.R. Walls and Brenda R. Cleveland
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 Bracteantha bracteata 'Matilda Yellow' 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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Nitrogen-deficient plants are noticeably smaller compared to the
control. Flowering occurs earlier than control plants.
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Low Substrate
Nitrogen
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A comparison of nitrogen deficient young and recently mature leaves:
Leaves are light green and slightly narrower than the control.
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With advanced symptoms the lower mature leaves are chlorotic and
the upper-portion of the plant has a pale green color. Flower stalks
are longer than the control and appear light greenish-yellow in
color.
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A close-up of the basal region of the plant shows a chlorosis on
the lower mature leaves. The lowest oldest mature leaves have a
yellow chlorosis starting at the leaf tips that progresses to the
leaf base, which ultimately turns brown and withers.
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| Phosphorus (P) (top) |
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Phosphorus-deficient plants are stunted and have darker green leaves
compared to the control.
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Low Substrate
Phosphorus
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Overall phosphorus-deficient plants have a dull green cast. Chlorosis
affects the mature leaf tips, which turn light yellow then brown.
As symptoms progress the plants remain stunted with little axillary
development.
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Chlorosis begins at the leaf tip as a yellow color which eventually
becomes necrotic and progresses to the base of the leaf. The necrotic
leaf tips often curl and wither.
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| Potassium (K) (top) |
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Initial symptoms show that the young to recently mature leaves
become chlorotic. The young leaves are also narrower than the control
and their margins are beginning to roll under. Overall the plants
are shorter than the control and the lower mature leaves have a
darker green color.
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Low Substrate
Potassium
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The youngest leaves are light green and have a brown leaf tip necrosis.
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The young and recently mature leaves have a downward architecture
and are slightly twisted. The upper mature leaves have a greenish-gray
chlorosis at the leaf tips and margins.
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At the advanced stage, the margins and tips of the mature leaves
turn a rusty-brown color. This region may also appear mottled.
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| Calcium (Ca) (top) |
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Initial symptoms for calcium-deficient plants shows black necrotic
spots on the midveins beginning at the base of the young and recently
mature leaves.
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Low Substrate
Calcium
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As symptoms progress, the young leaves become needle-like and deformed.
The upper recently mature leaves have a random interveinal chlorosis
and the midveins have necrotic spots which fuse to form grayish-black
patches.
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At advanced stages the plant size is much smaller than the control.
Young flower buds turn brown and develop necrotic spots, which in
turn abort. Complete withering of the young growth is followed by
total necrosis of the shoot tip.
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| Magnesium (Mg) (top) |
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Initial symptoms show a light green chlorosis on the recently mature
and mature leaves.
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Low Substrate
Magnesium
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The recently mature and mature leaves have a curled leaf architecture.
Margins bow downward and give the appearance of a cup-shaped leaf.
Faint light brown spots are fusing into patches on the chlorotic
leaf tips.
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As symptoms progress the yellow-green chlorotic tips of the recently
mature and mature leaves turn brown and papery. The leaf tips continue
to bow downward and some leaf tips are curling.
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| Sulfur (S) (top) |
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Sulfur-deficient plants are smaller than the control. There is
less axillary growth and plants are thin and spindly. The young
and recently mature leaves are narrower (sword-like) and have a
lime green color.
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Low Substrate
Sulfur
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The young and recently mature leaves are becoming narrow because
the margins roll under. A progression in color from the youngest
to the mature leaves: The youngest are lime green as compared to
the medium green mature leaves that resemble the control.
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The stem is light green and there is little to no axillary growth
in the shoot.
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With advanced sulfur deficiency the leaf tips and margins of the
chlorotic areas turn light yellow to white, followed by a brown
necrosis.
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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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Initial symptoms of boron-deficiency show that the youngest leaves
around the growing point are deformed. The basal regions of the
youngest leaves are wrinkled and twisted.
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Low Substrate
Boron
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As symptoms progress the axillary buds develop a brown necrosis
and abort, many times flowering ceases. The surrounding young leaves
develop a black necrosis and wither.
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In advanced stages the young to mature leaves have a wider and
whiter basal midvein that turns brown and moves from the leaf base
toward the tip. Chlorosis and necrosis occurs on the youngest leaves
which are very small and deformed. The upper mature leaves are glossy
and thick. Some of the flower buds at the growing point are underdeveloped
or have aborted.
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Overall in advanced stages the plants are very stunted and compact
with a thick canopy. Shoot elongation is less than the control and
the mature leaves are wider with a drooping architecture. Often
the plants are rigid to the touch with the leaves having a leathery
texture.
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| Copper (Cu) (top)
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Initial symptoms of copper-deficiency show that the plant is a
uniform light green color when compared to the control.
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Low Substrate
Copper
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As symptoms progress the recently mature and mature leaves cup
downward and their leaf tips arch upward. The young leaves have
developed brown necrotic patches on the tips.
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Flowers and flower buds of copper-deficient plants are bright yellow
compared to the yellowish-orange control buds.
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With advanced copper-deficiency the youngest and young leaves have
become needle-like and have a brown necrosis that causes them to
be very brittle.
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| Iron (Fe) (top)
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Initial symptoms develop as either a uniform or random light green
interveinal chlorosis on the younger leaves.
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Low Substrate
Iron
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As symptoms progress to an intermediate stage, the interveinal
chlorosis becomes more visible.
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At advanced stages the young leaves range from having a yellow-green
interveinal chlorosis to a uniform light yellow chlorosis. The recently
mature leaves have a greenish-yellow interveinal chlorosis which
starts at the tips and progresses to the base. A faint whitish-yellow
marginal chlorosis is on the recently mature leaves.
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Leaf comparison: The young and recently mature leaves are yellowish-white
and are beginning to show necrosis on the leaf tips as marginal
scorching. The tips are withered, shriveled and curled upright.
Interveinal chlorosis or a uniform chlorosis are also apparent on
some young and recently mature leaves. The lower mature leaves are
a dull green color.
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| Manganese (Mn) (top)
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Initial symptoms for manganese-deficient plants shows a lime green
uniform chlorosis of the young to upper mature leaves.
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Low Substrate
Manganese
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The young and recently mature leaves appear swollen (wider) than
the control. The midrib on the affected recently mature leaves is
a dark green color. Tan to white, shiny, sunken and undefined patches
are randomly appearing on the recently mature leaves.
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Manganese deficient plants at the advanced stage are overall a
light lime green color and have a dense canopy because of less axillary
elongation.
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The lower oldest mature leaves are dark green with a yellow marginal
chlorosis on the tips. A brown papery necrosis is on the leaf tips
of the recently mature and mature leaves. These leaf tips are curling
upward.
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| Zinc (Zn) (top)
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Some recently mature leaf margins are deformed causing the leaf
tip to turn to one side and cup downward.
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Low Substrate
Zinc
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Leaf comparison to the control: young and recently mature leaves
are twisting and the margins are rolling under.
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The youngest to the recently mature leaves have random brown necrotic
spots on their tips. These spots fuse into large brown patches and
the leaf tips become withered. Margins have rolled under and the
leaves are twisting, spiraling and are very brittle. The margins
of the mature leaves are brown on the middle of the leaf and progress
toward the tip; they are also rolling under and withered.
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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. Bobby Walls and Brenda Cleveland are NCDA Agronomic Division
Members NCDA&CS Agronomic Division, 4300 Reedy Creek Road Raleigh, NC
27607-6465. We would like to thank Paul
Ecke Ranch, Encinitas, CA., Tom Abramowski, Rockwell
Farms, Rockwell, N.C., and the North
Carolina Commercial Flower Growers' for grant support, Paul Ecke Ranch
for supplying the cuttings and Smithers-Oasis
for supplying the propagation medium.
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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