UCCE - Shade Tree Diseases Web Series

on Friday, October 02-30, 2020
in This is an online event ,


Join UC Cooperative Extension Advisor Jim Downer in this 5-part Shade Tree Disease webinar series.

When: Every Friday in October starting October 2, 12:30-2:00 PM (PDT)

Where: Virtual Webinar via Zoom (Links and instructions will be emailed to registrants)

Intended Audience: Arborists

Registration fee: $15 per session OR a discounted $50 fee when registering for all 5 sessions.

Continuing Education

DPR credits have been applied for: 1.0 of Other for each session

ISA Arborist credits have been applied for: 1.0 hour for each session

Learning outcomes for the series

  • Understand how shade tree diseases develop
  • Become a better shade tree disease diagnostician
  • Know the important types of shade tree disease
  • Learn practical shade tree disease control strategies

Workshop Schedule

October 2: I Plant Disease Basics

  • Learn about basic processes of pathogenesis (disease development)
  • Recognize the difference between biotic and abiotic diseases

What are plant diseases. There are two basic kinds biotic and abiotic. The plant disease tetrahedron helps to understand these basics and how they are distinguished. Diagnosis of disease begins with detecting symptoms and looking for signs of disease. Biotic diseases are caused by a variety of pathogens while abiotic diseases are associated with a range of environmental causes. Pathogenesis or disease development will be discussed for biotic and abiotic diseases.

October 9: II Biotic Diseases of Shade Trees I

  • Ability to diagnose canker, anthracnose and blight diseases of shade trees
  • Ability to differentiate bacterial and fungal cankers

Diseases of foliage and branches are the most observed diseases of shade trees. Diseases of the tree canopy are infectious and occur at specific times due to environmental predisposition. Some of these diseases are associated with insect vectors. This webinar will cover foliage and branch diseases and a few insect disorders that mimic blight diseases in shade trees.

October 16: III Biotic Diseases II

  • Learn how systemic symptoms can indicate very different disease causes (etiologies)
  • Understand pathogen survival and host requirements

This webinar will cover diseases of wood (decay), root rots and vascular wilt diseases. All of these diseases can be cryptic, often overlooked in early stages of development and each disease category has pathogens that can lead to the demise of shade trees. Many horticultural practices predispose trees to diseases. Learning how trees are predisposed helps to prevent disease development.

October 23: IV Abiotic Diseases of Shade Trees

  • Understand the patterns that develop in abiotic disease symptom expression
  • Learn how to detect soil conditions that underpin many abiotic diseases
  • Develop a tool kit for abiotic diagnoses

This webinar will cover disease of shade trees in absence of pathogens. Environmental conditions that cause disease are often associated with people, so sometimes these diseases are called people pressure diseases. Abiotic diseases require careful site assessments, a historical perspective of what happened in the past and tools to assess soil conditions. Mineral nutrient disorders often are affected by a variety of soil factors

October 30: V Control of Shade Tree Diseases

  • Learn how to prevent or reduce disease development in trees
  • Learn how to prevent spread of diseases in the urban forest

This webinar will focus on control of shade tree diseases. Once the diagnosis is done what can we do to slow the progress of disease. Control is often not cure but an attempt to prevent spread of disease or reduce its development within a tree. Canopy and root based strategies will be discussed. Chemical control, biological controls and cultural controls will be discussed. Integrative control using all possible approaches is also discussed.

Contacts for More Information


UC ANR Program Support Unit, anrprogramsupport@ucanr.edu or call 530-750-1361

Course Content:

Jim Downer, Advisor, UCCE Ventura County, ajdowner@ucanr.edu




This is an online event ,