Nutrient deficiencies of Argyranthemum frutescens


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

Fertility monitoring and management for Argyranthemum frutescens 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 Argyranthemum frutescens 'Comet 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
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Description

Possible Causes and Management
Nitrogen (N) (top)
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Nitrogen-deficient plants are noticeably smaller compared to the control. Flowering occurs earlier and is more profuse than the control. Axillary shoot growth is less.

Low Substrate Nitrogen
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The overall size of the plant is smaller due to a reduction in lateral shoot development. Flower stalks are longer than the control and light greenish-yellow. The lower mature leaves are chlorotic and the upper portion of the plant is pale green.

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Uniform, light yellow-green chlorosis appears on the lower mature leaves. As the symptoms progress, a random brown necrosis develops. Leaf size is 30 percent smaller.

Phosphorus (P) (top)
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Initially, phosphorus-deficient plants have darker green leaves than the control with a slightly stunted appearance.

Low Substrate Phosphorus
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As symptoms progress, the plants are smaller with little to no axillary shoot development. The leaves around the growing point express a greenish-yellow to light yellow chlorosis followed by a brown necrosis.

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

Potassium (K) (top)
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A smaller size and darker green color are the initial symptoms of potassium-deficient plants when compared to the control.

Low Substrate Potassium
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As symptoms advance, overall plant size is less and a greenish-yellow chlorosis appears on the mature leaf tips that progresses to a brown necrosis.

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Flower size is smaller and petals become paler pink compared to the control.

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The mature leaves turn uniformly greenish-yellow and the leaf tips become chlorotic, turning yellow-green then yellow. Necrosis begins on the leaf tips as brown, withered tissue.

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At the advanced stage, leaf size is smaller and a distinct leaf tip burn develops on the mature leaves.

Calcium (Ca) (top)
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Calcium-deficient plants are severely stunted and compact when compared to the control. The roots are stubby with very short secondary roots.

Low Substrate Calcium
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As symptoms progress, the leaf tips of the recently mature and mature leaves develop a yellow chlorosis. Plant size is smaller and axillary shoot growth is less.

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Young flower buds turn brown and develop necrotic spots, which in turn abort. Distinct yellowing of the mature leaf tips progresses toward the margin.

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As the deficiency advances, flowers become deformed and incomplete. Petals develop dark pink necrotic spots at their tips. Petal size is minute or smaller and petals are often missing.

Magnesium (Mg) (top)
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The leaf tips of the lower mature leaves develop a light greenish-yellow chlorosis as the initial symptom.

Low Substrate Magnesium
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A close-up of advanced symptoms shows leaf-tip chlorosis has progressed to a brown necrotic burn while the midveins remain green.

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Chlorosis and necrosis severely affects the lower mature leaves.

Sulfur (S) (top)
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Recently mature leaves of sulfur-deficient plants are smaller when compared to the control and express leaflet-tip chlorosis.

Low Substrate Sulfur
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As symptoms progress, the overall size of the plant is severely stunted and a greenish-yellow color is observed. At the growing point, chlorotic leaflet tips turn red.

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Advanced sulfur deficiency results in deformed flowers. The flower petals wither and roll under giving them a thin, needlelike appearance. The entire plant is light green with dark-red leaflet tips.

Micronutrients (top)
Photograph

Description

Possible Causes and Management
Boron (B) (top)
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Around the growing point, small, deformed axillary shoots cause a rosettelike appearance. Young leaf tips have a light-green chlorosis.

Low Substrate Boron
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Boron-deficient plants are stunted and compact. The terminal shoot has stopped growing and the mature leaves have a yellow chlorosis.

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Advanced symptoms of boron deficiency show that the young leaves are yellow with brown necrotic tip burn. Bud abortion occurs and flowering is severely decreased. Recently mature and mature leaves have a veinal chlorosis starting at the leaf tips that progresses toward the base.

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

Copper (Cu) (top)
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Initial symptoms show that the upper portion of the plant has a light greenish-yellow chlorosis with the mature leaves being dull green.

Low Substrate Copper
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As symptoms progress, the lateral branches have less shoots. Leaves are uniformly chlorotic and loose their sheen. Flowers are small, deformed and bleached compared to the control.

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Leaves are smaller and chlorotic. Eventually the chlorotic regions develop random necrotic patches on the leaf tips.

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Flower petals are bleach white and much smaller than the 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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A close-up of the yellow-green marginal chlorosis on the recently mature.

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A progression of a light-green chlorosis to a brown necrosis on young and recently mature leaves. Flowers are light pink to bleach white and slightly smaller in size.

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Recently mature leaves are yellow-green and the lowest leaves are dark green. Poor lateral branching causes iron-deficient plants to appear stunted. A brown necrosis on young leaf tips is observed.

Manganese (Mn) (top)
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Manganese-deficient plants develop a uniform light-green color on the youngest leaves beginning at the leaf tips and moving toward the leaf base.

Low Substrate Manganese
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A comparison of the recently mature leaves displays a uniform yellowish-green chlorosis when compared to the control.

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With advanced symptoms, the overall plant is lime green. The chlorosis originates in the upper part of the plant and progresses downward. Internodes are shorter than the control, causing the plant to have a compact appearance.

Zinc (Zn) (top)
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On the recently mature leaves, the central region of the leaf has a light-green chlorosis. Random brown necrotic spots appear on the margins of the leaflets.

Low Substrate Zinc
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The necrotic spots have fused along the margin and have spread to the entire 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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