Diseases of Greenhouse Crops and Their Control

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Diseases of Greenhouse Cropsand Their Control
Brian D. Hudelson Department of Plant
Pathology University of Wisconsin-Madison/Extensio
n
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Diseases of Greenhouse Cropsand Their Control
Damping-Off

• Pathogens Pythium spp., Rhizoctonia solani,
  Fusaruium spp.
• Hosts
• Seedlings of virtually anything

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Diseases of Greenhouse Cropsand Their Control
Damping-Off

• Control
• Moderate soil moisture
• Use a soil with adequate drainage
• Dont overwater
• Germinate seeds at higher temperatures
• Use fungicides to protect seedlings
• Etridiazole, metalaxyl, mefenoxam, captan
• Applied as a seed treatment or drench

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Diseases of Greenhouse Cropsand Their Control
Root Rots

• Pathogens Pythium spp., Phytophthora spp.,
  Rhizoctonia solani, Fusarium spp.
• Hosts
• Virtually anything
• Greenhouse Poinsettia, geranium, begonia

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Diseases of Greenhouse Cropsand Their Control
Root Rots

• Control
• Moderate soil moisture
• Use a soil with adequate drainage
• Dont overwater
• Use fungicides to prevent infections
• Etridiazole, metalaxyl, mefenoxam, fosetyl-Al
• PCNB
• Thiophanate-methyl

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Diseases of Greenhouse Cropsand Their Control
Root Rots

• Control
• Decontaminate recycled water
• Filtration
• Irradiation
• Chemical treatment

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Diseases of Greenhouse Cropsand Their Control
Powdery Mildews

• Cause Erysiphe sp., Microsphaera sp.,
  Uncinula sp., Sphaerotheca sp.,
  Phyllactinia sp., Podosphaera sp. (Oidium
  sp., Ovulariopsis sp.)
• Hosts
• Virtually everything
• Greenhouses Grape-leaf ivy, oak-leaf ivy,
  jadeplant

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Diseases of Greenhouse Cropsand Their Control
Powdery Mildews

• Control
• Remove diseased plant material and debris
• Reduce humidity
• Use fungicides to prevent infections
• Baking soda (1.5 Tsp/gal) and horticultural oil
  (3 Tsp/gal)
• Dinocap, dithiocarbamates, myclobutanil,
  triadimefon, triforine, sulfur or
  thiophanate-methyl
• Apply when humidity gt60-70
• 7-14 day application interval

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Diseases of Greenhouse Cropsand Their
ControlXanthomonas Leaf Diseases

• Cause Xanthomonas campestris
• pv. poinsettiicola pv. hederae
• pv. begoniae pv. dieffenbachiae
• pv. pelargonii
• Hosts
• Poinsettia Ivies
• Begonia Dumbcanes et al.
• Geranium

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Diseases of Greenhouse Cropsand Their
ControlXanthomonas leaf diseases

• Control
• Start with clean propagation materials
• Follow strict sanitation procedures when working
  with plant materials
• Remove symptomatic plants
• Remove contaminated plant debris
• Disinfest greenhouses after production

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Diseases of Greenhouse Cropsand Their
ControlBacterial Wilt

• Cause Ralstonia solanacearum
• races
• biovars
• Hosts
• Geranium
• Many other hosts

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Diseases of Greenhouse Cropsand Their
ControlBacterial Wilt

• Control
• Start with clean propagation materials
• Follow strict sanitation procedures when working
  with plant materials
• Remove symptomatic plants
• Remove contaminated plant debris
• Disinfest greenhouses after production

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Diseases of Greenhouse Cropsand Their
ControlViral Plant Diseases

• Causes
• Impatiens necrotic spot virus (INSV)
• Tomato spotted wilt virus (TSWV)
• Tobacco mosaic virus (TMV)
• Cucumber mosaic virus (CMV)
• Dasheen mosaic virus (DsMV)
• Cymbidium mosaic virus (CyMV)
• Odontoglossum ringspot virus (ORSV)

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Diseases of Greenhouse Cropsand Their
ControlViral Plant Diseases

• Hosts
• Wide-range
• INSV
• TSWV
• TMV
• CMV
• DsMV

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Diseases of Greenhouse Cropsand Their
ControlViral Plant Diseases

• Hosts
• Narrow-range
• CyMV
• ORSV

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Diseases of Greenhouse Cropsand Their
ControlViral Plant Diseases

• Control
• Start with clean propagation materials
• Follow strict sanitation procedures when working
  with plant materials
• Remove symptomatic plants
• Remove contaminated plant debris
• Remove potential weed hosts
• Control insect vectors

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Diseases of Greenhouse Cropsand Their
ControlFoliar Nematodes

• Cause Aphelenchoides ssp.
• Hosts
• Wide host range
• Greenhouse African violets, ferns,
  begonia chrysanthemum

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Diseases of Greenhouse Cropsand Their
ControlFoliar Nematodes

• Control
• Start with clean propagation materials
• Follow strict sanitation procedures when working
  with plant materials
• Remove symptomatic plants
• Remove contaminated plant debris
• Avoid overhead irrigation

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Diseases of Greenhouse Cropsand Their
ControlRoot Knot Nematodes

• Cause Meloidogyne ssp.
• Hosts
• Wide host range
• Greenhouse Tomato

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Diseases of Greenhouse Cropsand Their
ControlRoot Knot Nematodes

• Control
• Start with clean propagation materials
• Use soil-less growing media or pasteurized soil
• Discard infected plants

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Diseases of Greenhouse Cropsand Their
ControlCysts Nematodes

• Cause Cactodera ssp. (Cactus cyst nematode)
• Hosts
• Cacti
• Other succulents

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Diseases of Greenhouse Cropsand Their
ControlCyst Nematodes

• Control
• Start with clean materials
• Use soil-less growing media or pasteurized soil
• Discard infected plants

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Diseases of Greenhouse Cropsand Their
ControlCultural Control

• Avoid pathogens
• Buy seed (certified) from a reputable source
• Inspect growing stock for above and below ground
  pathogens/diseases
• Inspect stock for insect pests
• Control alternate hosts
• Use non-contaminated water

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Diseases of Greenhouse Cropsand Their
ControlCultural Control

• Avoid conducive environmental conditions
• Soil moisture
• Humidity
• Have balanced nutrition
• Prevent heat stress
• Be aware of activities surrounding your operation

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Diseases of Greenhouse Cropsand Their
ControlCultural Control

• Sanitation
• Disinfest tools
• Adequately clean pots and benches
• Pasteurize soil prior to use
• Decontaminate recycled water
• Remove diseased plants promptly
• Remove senescent plant parts promptly

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Diseases of Greenhouse Cropsand Their
ControlChemical Control

• Use registered/labeled materials only
• Use products safely
• Applicator
• Worker
• Get training

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Diseases of Greenhouse Cropsand Their
ControlChemical Control

• Protectant fungicides/bactericides
• Systemic fungicides/bactericides
• Fumigants

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Diseases of Greenhouse Cropsand Their
ControlBiological Control

• Disease resistance
• Biological pesticides
• Plant extracts
• Antagonistic microorganisms

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Diseases of Greenhouse Cropsand Their
ControlWhere to Go for Help
Plant Disease Diagnostics Clinic Department of
Plant Pathology University of Wisconsin-Madison 16
30 Linden Drive Madison, WI 53706-1598 (608)
262-2863 bdh_at_plantpath.wisc.edu http//www.plantpa
th.wisc.edu/pddc