Dwarf allamanda (Allamanda nerifolia)
Dwarf allamanda (Allamanda nerifolia) is a durable tropical hardy in USDA Hardiness Zones 9-11. It can be used as a containerized ornamanetal or bedding plant. The plant is well regarded for its fleshy, trumpet-shaped, yellow flowers.
Dwarf allamanda performs best in poor, dry soils and full sun. It has very few pest problems and a moderate salt tolerance.
Fertilizer recommendations of 100 to 150 parts per million nitrogen help to increase growth during summer. Nutrient deficiencies can occur during production. Symptoms have been reported as chlorosis of both the young and youngest leaves.
Fertility monitoring and management for dwarf allamanda requires a balancing of the plant’s needs. Growers must be aware and manage the root substrate pH and electrical conductivity and provide adequate, but not excessive, levels of all essential elements.
Using a plant diagnostic laboratory to identify the source of problems is still the best way to ensure accurate diagnoses.
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Nutrient deficiency descriptions are unavailable for most perennials, yet growers must often make quick diagnoses. A research project initiated at the University of Florida in Milton documented deficiency symptoms in vegetatively propagated Allamanda nerifolia to assist growers.
Pictures related to the nutrient deficiencies series may accessed by viewing the PDF files of the pages that originally appeared in GMPRO magazine: Page 1. Page 2. Page 3. Page 4. Page 5.
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Nitrogen (N)
Initially, young and the youngest leaves of nitrogen-deficient plants are light green.
As symptoms progress, a patchy interveinal chlorosis develops on the mature leaves. Midveins become greenish-white and the oldest leaves express a uniform yellow color.
Advanced symptoms include stunted plants, greenish-yellow upper growth and dull-yellow mature leaves with necrotic tips.
Phosphorus (P)
Phosphorus-deficient plants have darker-green foliage than the control.
The entire plant expresses a dullish-green cast with purple-pigmented stems. Lower leaves turn chlorotic.
Under advanced symptoms, a splotchy yellow chlorosis appears on the recently mature and mature leaves.
Potassium (K)
Initially, potassium deficiency is observed as a faint interveinal chlorosis of the recently mature leaves with greenish-yellow midribs.
As symptoms progress, chlorosis of the shoot tip is expressed and stems turn purple. Older leaves bend downward.
Comparison of potassium-deficient leaves to the control. Note (from right to left) the basal chlorosis on the youngest leaves, the prominent dark-green midvein and dull-yellow chlorosis on the mature leaves, and the tannish-brown necrosis on the oldest leaves.
Calcium (Ca)
Calcium-deficiency symptoms develop first as an overall darker-green appearance than the control with glossy recently mature leaves.
Over time, tips of the young and recently mature leaves curl downward, followed by development of interveinal chlorosis on the young and youngest leaves.
Calcium-deficient young leaves are narrower than the control’s young leaves.
Magnesium (Mg)
Magnesium deficiency begins as a faint interveinal chlorosis on the recently mature leaves.
As symptoms progress, a yellowish-green cast appears over the entire plant.
Advanced symptoms appear as a severe interveinal chlorosis, which is accompanied by whitish-tan necrotic spots on the margins and the leaf interior.
Sulfur (S)
Initially, sulfur-deficient plants are smaller with pale-green stems.
As symptoms progress, a distinct yellow-green chlorosis appears on the young and recently mature leaves. The oldest leaves turn yellow.
Recently mature leaves are straplike with pale-yellow margins and midveins.
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Boron (B)
Boron-deficient plants initially experience an inhibition of axillary shoot growth. The shoot tips become compact and chlorotic.
At the advanced stage, chlorotic youngest and young leaves become thick, spindly and brittle.
Copper (Cu)
Copper-deficient plants have shorter internodes and duller-green foliage when compared to the control.
As symptoms progress, recently mature leaves express a faint interveinal chlorosis and the youngest leaves are narrow and yellow-green.
Comparison of copper-deficient leaves to the control. Note (from right to left) the marginal chlorosis on the young leaves, dark-green mature leaves, and splotchy chlorosis on the oldest leaves.
Iron (Fe)
Initially, deficient young and youngest leaves express a basal yellow-green chlorosis that migrates toward the leaf tip.
As symptoms develop, chlorosis progresses to the recently mature leaves, while the oldest leaves remain dark green. The light-green chlorosis progresses to yellowish-green. The midrib is pale green.
Advanced symptoms include yellowish-white young leaves and light-yellow recently mature leaves. The midrib is pale green.
Manganese (Mn)
Manganese deficiency begins with the recently mature leaf margins developing a faint chlorosis. As symptoms progress, the young leaves become narrow and chlorosis expands over the leaf surface.
A close-up of the whitish-yellow young and youngest leaves.
Yellowish-white chlorosis occurs on the young and youngest leaves while the mature leaves express a distinct interveinal chlorosis.
Zinc (Zn)
Young growth on zinc-deficient plants feels thicker than the control. A greenish-yellow to yellow-white chlorosis develops on the young leaf bases.
As symptoms progress, the youngest leaves become narrow and deformed.
Under advanced deficiency conditions, bright, yellowish-white young leaves become upright and extremely rigid.
-James L. Gibson, Jude Groninger, Sharon Wombles, and Kathryn Campbell
James Gibson is assistant professor, Jude Groninger is senior laboratory technician, Sharon Wombles is a former undergraduate research assistant and Kathryn Campbell is an undergraduate research assistant, University of Florida, Institute of Food and Agricultural Sciences, West Florida Research and Education Center, 5988 Highway 90, Building 4900, Milton, FL 32583; (850) 983-5216, Ext. 103; jlgibson@ifas.ufl.edu.
The authors thank the Fred C. Gloeckner Foundation for grant support, Smithers-Oasis for the propagation medium, Hatchett Creek for plant material and Quality Analytical Laboratories for tissue analysis. The authors also thank Christopher Cerveny, Leah McCue, and MariahWilliams for their technical assistance.
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