Updated Best Management Practices

On May ….2008 Tree Solutions representatives Ryan and James Neve attended the  California Oak Mortality Task Force (COMFT) Sudden Oak Death wildland training session. The meeting was held at Thomas Fogarty Winery which is located off Skyline Blvd. in Woodside, California.

The featured speakers were; Kamyar Aaram/UC Davis, Matteo Garbelotto/UC Berkeley, and Steve Swain/ Environmental Horticulture Advisor for Marin and Sonoma Counties. Doug Schmidt conducted a field demonstration showing Agrifos/Pentrabark application techniques.The most current research results and best management practices were presented in both an indoor room setting with slideshow presentations followed by field stations where application techniques and in field scenarios were observed and discussed.
The following is a condensed summary of the meeting and the latest Sudden Oak Death information as presented by the speakers:

Kamyar Aaram/UC Davis:

  • 2 million acres infested which is only 10% of total possible
  • Tan oaks become infected and die in 1-2 years
  • Infection occurs
  • Drought stress triggers the decline and mortality

Best Management Practices

  • Clean shoes, bike tires etc.
  • Isolate nursery bought Rhodies for two months and monitor for disease before planting
  • Canyon oaks (Q. chrysolepis) added to list of susceptible trees
  • Twig and foliar blight
  • No stem cankers
  • Rarely killed by disease
  • Interior oaks (Q. wislizenii) not on task force list but seedlings may become infested in severely infested areas
  • Recommends treating until they know for sure
  • Tan oak leaf and stem infections concentrated on leaf veins
  • Oak infections can take up to two years to show on trees and 2-5 years to kill tree
  • Subdue does not eliminate pathogen

Sanitation issues:

  • Tree companies should have written policies for their workers

Matteo Garbelotto

  • Works  best as a preventative
  • Drought periods kill trees faster
  • Once infected, too late to treat
  • Asymptomatic trees can be infected 6 mos.-1.5 years
  • Protect all green trees
  • Clamydospores are not directly responsible for infections
  • Takes a long time to form zoospores
  • Bay leaves may become infected every 48 hrs.
  • Bay laurel abatement advocated, remove small bays not large ones 200 meters(He may have said feet) the critical zone
  • Takes four weeks for material to move into trees
  • November best time to treat
  • Treatment effective for up to 1.5 years
  • Black oaks
  • Injections in the spring
  • Spray fall because spray will stay on bark to be used when ready
  • No data to back up this statement
  • Symptoms not enough to diagnose
  • Pathogen moves 200-300 meters easily
  • Tan oak faces extinction because of low resistance

Chemical treatments

  • Treatment does not work on Bay Laurels
  • Combine oak treatment with inoculums reduction
  • Add compost
  • It works directly against the pathogen on the ground and reduces infection from splash mechanism
  • Spread 3ft. diameter from trunks
  • Treatment will not help 10% of oaks
  • Nov. and late Feb.-March best application times

Advocating injections

  • Went to Texas and saw good wound recovery of oaks being treated for oak wilt for 20 years
  • Injection holes drilled into tree just past cambial layer for best uptake
  • Root flare injections not necessary
  • The outer rings of xylem are the best placement of material
  • Needle type of injection systems do not work
  • Better to push material into tree with some pressure
  • Non pressure systems do not work


  • Soil or trunk applied applications do not work
  • CA encourages Phytopthora thinks this is a waste of time and money
  • Moist chips are infectious
  • Chip and spread do not pile


  • Fresh cuts most susceptible to infection 10X more than bark infections
  • Prune late summer to fall only


  • Soil material is very infectious movement must be addressed
  • Regular/bad
  • Occasional/ok


  • Replace in spring buy plants
  • Segregate and then watch for 2 mos., if Phytophthora symptoms show, destroy plant

Steve Swain

  • Containment is the focus
  • Pathogen moves up to 3 miles
  • Spraying of wild land areas is impractical because of expense
  • 6-20 feet critical clearance zone
  • Some oaks are resistant
  • Majority are not, even if resistant, bay laurels can infect
  • 3 strategies of control
  • Heavy inoculums areas
  • Stand preservation and hazard reduction


  • Containment stand treatment to remove foliar hosts create barrier strip


  • Eradication
  • Uninfected stands
  • Remove bay laurels and tan oak because they are vectors
  • Fire considerations
  • 5-8 dead trees per acre no additional fire danger
  • 40+ is bad
  • Concluded and constantly stated that everything he is saying has very limited data
  • Approaches are experimental and is based on basic hypothesis
  • Concerned about cryptic infection


Certified Arborist WE-6717A

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