Seminar Dates: November 13, 2025 11:30 AM
Seminar Cost: $45.00 Register Now
Seminar Description:
This seminar offers an in-depth look at the hidden half of trees: the roots. Attendees will gain a practical understanding of where roots grow, how they function, and the ways they differ across species—including monocots and trees with clonal or grafted root systems. We’ll explore the symbiotic relationships between roots and mycorrhizal fungi, as well as the role of mulch in supporting healthy root zones. The session will also focus heavily on diagnosing and managing root diseases such as Armillaria, Phytophthora, Ganoderma, sulfur fungus, and crown gall. Finally, strategies for root system preservation will be discussed to support long-term tree health and urban landscape sustainability.
Learning Objectives:
1. Identify the structure, function, and distribution of tree roots, including variations in root types such as monocots and clonal root systems.
2. Recognize the signs, causes, and implications of common root diseases, including Armillaria, Phytophthora, Ganoderma, sulfur fungus, and crown gall.
3. Apply best practices for root system preservation, from selection and planting to long-term maintenance and mycorrhizal support.
Susan Sims
Susan Sims is an ISA Board Certified Master Arborist, CA Urban Forester, and an ISA Qualified Tree Risk Assessor. In 1972, Susan, alongside her husband, Gary, started Sims Tree Health Specialists, Inc. Since then, the family became a household name in the tree care industry, known for their education and experience in tree care efforts. In 1997, they further advanced their education efforts by starting Sims Tree Learning Center (TLC), a botanical garden and arboretum that focuses on the research and education of trees. Though she is mostly retired, you can still find Sue spending her days gardening in the olive orchard located at the family’s Northern California branch of Sims TLC and volunteering in causes dedicated to the education of trees and gardening.
