Nutrient deficiencies of Osteospermum ecklonis

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

Fertility monitoring and management for Osteospermum ecklonis 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 Osteospermum ecklonis 'Kalanga' 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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Nitrogen-deficient plants are noticeably smaller due to a reduction in lateral shoot development.

Low Substrate Nitrogen
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With leaves removed, it is clear to see that the nitrogen-deficient stem has turned red.

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Overall the plants are severely stunted and are uniformly light green.

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At the advanced stage the lower foliage turns from a light green to yellow, which eventually develops a tan papery necrosis. Small brown to red spots appear on the recently mature leaves of the upper foliage and fuse together to form brown patches.

Phosphorus (P) (top)
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Initially phosphorus-deficient plants have darker green upper leaves than the control with a slightly stunted appearance. The stem turns a brownish-red color and progresses from the base upward.

Low Substrate Phosphorus
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As symptoms progress, brown necrotic patches form on the tips and margins of the lower mature leaves.

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Phosphorus-deficient leaves are slightly smaller and pale green when compared to the control. Marginal leaf tip chlorosis moves toward the base and quickly turns to a brown papery necrosis.

Potassium (K) (top)
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Initial symptoms of potassium-deficient plants include small chlorotic spots appearing at the leaf tips of the lower mature leaves. Leaves are slightly deformed and rolled under, when compared to the control.

Low Substrate Potassium
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At the advanced stage, overall plant size is smaller and necrosis begins on the mature leaf tips and progresses to the base as brown withered tissue.

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Leaf size is smaller and the mature leaves turn uniformly greenish-yellow. The leaf tips become chlorotic turning yellow then brown resulting in a papery burn.

Calcium (Ca) (top)
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Initial symptoms for calcium-deficient plants include smaller deformed young leaves with a brownish-tan discoloration starting at the base progressing to the leaf tip.

Low Substrate Calcium
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As symptoms progress the young leaves develop small brown to black spots on the already discolored region. Increased deformation of the young leaves is apparent.

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Necrosis quickly advances, as young leaves turn a rusty brown color and become withered. A tan necrosis moves from the base to the tips on the recently mature leaves.

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Flower stalks turn greenish-yellow then brown and eventually collapse. As the deficiency advances, flowers become deformed and incomplete.

Magnesium (Mg) (top)
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Magnesium-deficient plants have a light green interveinal chlorosis.

Low Substrate Magnesium
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The light green chlorosis advances to a greenish-yellow to yellow interveinal chlorosis. Within the yellowing areas small tan translucent spots appear which quickly turn brown and begin to fuse together.

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Advanced symptoms include marginal leaf necrosis and yellow interveinal chlorosis.

Sulfur (S) (top)
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Plants are slightly smaller and young leaves have a light greenish-yellow color.

Low Substrate Sulfur
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As symptoms progress, the overall size of the plant is severely stunted. Young and recently mature leaves of sulfur deficient plants are light green with yellow marginal chlorosis, when compared to the control.

Micronutrients (top)
Photograph
Description
Possible Causes and Management
Boron (B) (top)
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Young leaves of boron-deficient plants are deformed and slightly darker.

Low Substrate Boron
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Around the growing point, small deformed axillary shoots cause a rosette-like appearance to be observed.

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Boron-deficient plants are stunted and compact because the terminal shoot has stopped growing.

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Advanced symptoms of boron deficiency show that the leaves are severely deformed and leathery. Small brown necrotic spots appear in the middle of the leaf. Brown necrosis also occurs on the basal region of the midvein progressing toward the leaf tip.

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Boron deficiency causes the flowers to be incomplete with deformed ray petals.

Copper (Cu) (top)
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Initial symptoms show small brown spots on the recently mature leaf tips.

Low Substrate Copper
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As symptoms progress, the spots fuse together and form yellow to brown necrotic patches, when compared to the control.

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The patches turn to large tan papery regions at the leaf tips.

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Plants are darker green with advanced leaf tip necrosis, when compared to control.

Iron (Fe) (top)
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Initial symptoms develop as a light green chlorosis on the younger leaves.

Low Substrate Iron
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Recently mature leaves have a light green interveinal chlorosis.

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(Left) Severe interveinal chlorosis of the young to upper mature leaves. (Right) Advanced symptoms develop into bleaching of the young leaves; recently mature leaves are light green while the lowest mature leaves remain green.

Manganese (Mn) (top)
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Manganese-deficient leaves develop a uniform light green color beginning at the leaf base that moves toward the leaf tips.

Low Substrate Manganese
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Small translucent spots begin to fuse together forming small brown patches on the recently mature leaves.

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With advanced symptoms, the overall plant is a lime green color. The chlorosis originates in the upper part of the plant and progresses downward.

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A comparison of the recently mature and mature leaves displays a uniform yellowish-green interveinal chlorosis, when compared to the control. Necrotic spots and patches appear on the maturing leaves beginning in the middle and progress toward the tip.

Zinc (Zn) (top)
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On the recently mature leaves, the leaf tips have a light green chlorosis and plants are slightly smaller than the control.

Low Substrate Zinc
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Random brown necrotic spots appear on the margins of the leaves giving the leaf tips a brown cast. Overall size of the plant is 40% smaller than the control.

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The leaves are a light greenish-yellow color and slightly smaller than the control. The necrotic spots have fused along the margins of the leaf tips and subsequently form large necrotic regions toward the base of the leaf.

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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