Nutritional Disorders of Herbaceous Landscape Plants

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Nutritional Disorders of Herbaceous Landscape
Plants

• Dr. Holly Scoggins
• Dept. of Horticulture

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Terms to know

• Chlorosis
• Yellowing of tissue due to lack of chlorophyll
  production
• Necrosis
• Dead tissue (brown crispy)
• Margin
• Edge of leaf.. marginal necrosis
• Interveinal
• Tissue between leaf veins interveinal
  chlorosis

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The call

• My begonia crop looks a mite bit funny

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The inspection

• Entire house or crop-specific
• Entire crop or sporadic event
• Is it a crop that is prone to nutritional
  problems?
• Symptoms on older leaves or younger leaves?

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The interrogation

• Verifychemicals/pests/pathogens or atmosphere not
  the culprit
• What fertilizer formulation, concentration,
  application method, and frequency?
• Tested the pH and soluble salts lately?
• Growing media AND end-of-hose

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Symptoms older or younger leaves?

• Mobile (symptoms appear in older leaves)
• N P K Mg S
• Immobile or slightly mobile (symptoms appear in
  newer leaves)
• Ca Fe Mn Zn B Mo

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Whats the crop? Heavy feeders

• Vegetatively-propagated Petunia
• Zonal Geranium
• Poinsettia
• Bedding impatiens
• Hanging baskets/containers
• Why?

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Whats the crop? Light feeders

• Most perennials
• Especially spring-bloomers (i.e. columbine)
• Ornamental grasses
• Cyclamen, Cineraria, snaps, other cool house
  crops
• New Guinea Impatiens

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Media testing results pH?

• Impacts nutrient availability
• Especially micronutrients

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Pour-through method
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Nutrient availability in soilless media
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Which fertilizer used? Can impact pH

• Acid vs. basic residue
• Type/ratio of nitrogen
• Nitrate-N
• Ammonium-N
• Root-zone reaction

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Acidity and Basicity of Common Fertilizers(lbs
of CaCO3 equiv. per ton)
Acid Neutral Basic
20-10-20 15-16-17 15-5-15
15-15-15 20-0-20 13-2-13
9-45-15 15-0-15
10-30-20 15-0-0
20-20-20 13-0-44
21-7-7
100 formulations at http//www.msue.msu.edu/aoe
/floriculture/Formulations1.PDF
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How much fertilizer applied?

• Formulation, concentration, frequency
• Concentration given as amount of N
• Increase in N (i.e. 150 ppm to 300 ppm) results
  in increase in other salts

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Formulation Guaranteed Analysis

• Nitrogen form
• Other macro and micro nutrients

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Media testing results EC

• Interpretation depends on the testing method
• 12, pour-through, etc.
• Too high?
• Often whitish deposits on top of media
• Plants can appear wilted even when watered
• Leaf necrosis
• Solution LEACH!

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Suspect micronutrient toxicity?

• Switch from peat-lite formulations to general
  purpose
• Reduces level of micronutrients added
• Drive pH up with proper fertilizer selection
• 13-2-13, 15-0-15 (Nitrate forms)

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Need all that phosphorous???

• Plants actually use very little
• Excess can cause stretch
• Try low-P formulations
• P should be 1/3 to 1/5 N concentration

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Some suspect crops and associated disorders
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Chlorotic lower leaves

• Underfed! Nitrogen deficiency
• EC of less than 0.5 ds/m with pour-through
• Concentration?
• Check injector
• Frequency?
• pulse feeding

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Marigolds and iron toxicity

• African marigolds
• Annual vinca, New Guinea Impatiens
• Bronze speckle, downward curling

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Iron toxicity

• Most likely over-application of Fe chelate
• Present in many water-soluble fertilizer
  formulations (EDTA or (DPTA)
• Adding more N adding more micros
• Scotts Geranium special 15-15-15

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Poinsettia needs more Mo!

• Molybdenum deficiency
• Zinc can be a problem, too
• Can use specific formulation
• Can add micros

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Iron deficiency Petunia problems

• Also problem with pansy, vinca, snapdragons
• Use fertilizer with micros
• Lower pH to help

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Cool season crops and Phosphorus deficiency

• Plugs started in late winter
• Pansies, violas, veggie transplants
• Stunting (growth restriction), purple cast

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Problems at the growing point

• Boron or Calcium deficiency
• B? Brittle leaves and stems

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Growing pointcont.

• Calcium deficiency
• Distorted young leaves
• Upward cupping, rippled

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Calcium (Ca)

• Transported through plant via transpiration
• Restricted transpirationCa deficiency
• Hi humidity, cloudy, cool
• Low pH faster leaching of Ca
• Source
• Dolomitic lime (CaCO3 MgCO3)
• Cannot add after the fact
• Calcium nitrate

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got interveinal chlorosis?

• Deficiency
• Mobile - mature leaves
• Many crops susceptible
• Gerbera, petunia etc.

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Magnesium (Mg)

• Antagonistic with Ca and vice-versa
• Lots of calcium carbonate in water
• Recommended ratio of 31 to 51 CaMg
• Source
• Dolomitic lime (preplant)
• Epsom salts (MgSO4 .7H20)

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Good Resources

• http//www.umass.edu/umext/floriculture/fact_shee
  ts/greenhouse_management/fert.html
• http//www.ces.ncsu.edu/depts/hort/floriculture/
• Floriculture Principles and Species (2nd ed.)
  2005. Dole and Wilkens, Pearson / Prentice Hall.
  (worth every penny!)

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Questions (and perhaps) answers
Virginia Tech Floriculture