IPM for Bonsai

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IPM for Bonsai
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Why IPM for Bonsai?

• Bonsai nurseries need effective pest management
  strategies.
• Backyard hobbyists want to reduce the use of
  chemicals around the house.
• Small size makes bonsai prone to rapid
  infestations.
• Dwarfed trees have little tolerance for
  phytotoxic insecticides.
• Specimen trees might be hundreds of years old and
  worth tens of thousands of dollars.

Chinese elm killed by mites
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The Role of Tree Stress in IPM

• Trees die in two ways
• Rapid death, or
• A decline spiral consisting of
• Pre-existing conditions,
• Inciting Events,
• Contributing Factors.

Typical Tree Decline
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The Role of Tree Stress in IPM Continued

• All bonsai has pre-existing stress.
• Pruning and wiring is an inciting event.
• IPM is required after pruning to prevent
  contributing insect stress factors leading to
  tree death.

Does this tree look stressed?
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Typical Pests

• Aphids
• Mites
• Whiteflies
• Scales
• Mealybugs
• Others temperate and greenhouse pests

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Quarantine Concerns

• Many trees imported from Asia.
• Insects on imported trees may exhibit increased
  pesticide resistance because of poor cultural
  practices.
• Invasive nematodes accidentally introduced in
  Europe on bonsai.
• Longhorn beetles reported at bonsai nurseries in
  Georgia and Wisconsin.

Longhorn Beetle Exit Hole on Imported Tree
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Monitoring and Thresholds

• Standard monitoring methods (sticky cards, etc.)
• Threshold variation Field grown stock Vs.
  Specimen plants.
• Three crucial threshold factors
• Limited defoliation and leaf damage should be
  accepted.
• No tolerance for wood damaging insects.
• Apicial dominance is crucial, especially in
  coniferszero tolerance for meristematic tissue.

Should these two plants have the same damage
threshold?
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Treatment Practices

• Physical Screenhouses, tanglefoot, hand removal,
  hotwater treatments, etc.
• Biocontrol Highly effective on bonsai in
  confined areas because of limited biomass.
• Predatory mites, Cryptolaemus montrouzieri,
  Coccinellidae, lacewing larva will control most
  common pests.
• Chemical Traditional approach relies on nicotine.

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Case Study Spider Mites on Zelkova

• Pre-existing Stress
• Imported Plants.
• Stippling and webbing monitored several weeks
  after arrival.
• Phytoseiulus persimilis released.

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Case Study Spider Mites on Zelkova Continued

• Inciting Event
• Biocontrol effective until pruning and repotting
  occurred.
• Contributing Factors
• Whiteflies appear.
• Visual threshold for damage surpassed.
• Chemical treatment initiated biocontrol
  re-established.

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Thank you!

• 400 Year Old Japanese Black Pine