Root Disease Management Course - The Role and Impact of Root Diseases

DAY 1 - Classroom Session 1 Participant Objectives:

 The Forest Practices Code Root Disease Management Guide Book:

A. The Role of the RDM Guide Book -
About 10 min.
B. What the RDM Guide Book Contains - About 20 min.
The Role and Impact of Root Disease - About 30 min.
Step 1 of the 5-Phase Management Process (optional) - About 30 min.
Root Disease Identification - About 1 hr.

 - Understand and be able to explain the role of the RDM Guide.

- Learn how to consider root disease in silviculture and stand management prescriptions.

- Be able to assess the inherent root disease risk in a particular zone.

- Become familiar with the appearance of the three main root diseases in B. C. under various conditions and in various species.



 Instructions  Key Points  Visual Aid

The intention of this section is to convey that:

·Root disease in unmanaged forests is usually in balance with the ecology and hosts, and has some good effects.

· Root disease in managed forests can interfere with silviculture and stand objectives, but balance can be achieved with effective management.



























Adjust the amount of information you provide on root disease impact depending on knowledge levels and time available.






















To emphasize the impact of root disease, you may wish to use some of the timber impact figures contained in the reference material in the Participants' Guide.


In Unmanaged forests . . .

· are components of forests

· cause endemic disease that is in balance overall with hosts

· biological or environmental changes cause fluctuations in disease levels

· dead trees provide habitat for animals

· gaps sometimes allow for snow retention

·act as decomposers and contribute to processes of:

·nutrient cycling
·gap dynamics
·ecological succession

· But, Armillaria can adversely affect herbs and shrubs, thus also ungulates

In Managed Forests . . .

· Important that a balance is achieved between the pathogen, site ecology, and other factors

· Important that management objectives and prescriptions are developed in light of constraints of pathogen biology and site ecology

· Important to recognize and understand pathogens in each ecosystem

· Forestry activities can significantly alter disease expression by:

- creating new food sources and thus triggering disease spread.
- causing an alteration in species composition and stand structure, especially density
- regeneration/understory release, especially hardwoods

· Ecosystembased forestry management strives:

- to maintain function of root pathogens
- NOT to create conditions that favor pathogens over other ecological site factors


· Root disease is very serious and must be considered at all levels of planning

General Impact

· Are widespread in all forested B.C. ecosystems

· Can reduce tree growth, lower wood quality, cause early mortality

· Impacts wildlife, visual quality, water quality and production, and other resources

· Should be considered at all levels of planning even if not always treated

· Increases management complexity and risk

- limits species selection
- intensive forestry carries high risk; may trigger disease silviculture investment may be wasted if root disease is not managed effectively, but cost of management may be quite high

· All species are susceptible to most types of root disease

- Trees of any age are susceptible
- Likelihood of infection increases with age (because root contact increases)
- Impact decreases with age: with Armillaria, trees with large root collars take longer to be girdled and therefore the mortality rate partly depends on tree size and thus age; with Laminated, trees 80 to 100 years old may survive for 15 years; with Tomentosus, it takes longer to kill older trees.


Impact of Armillaria

· Causes some plantations to become NSR (which were established without recognizing or treating root disease)

· Disturbance increases disease

· Is a relationship between vigour and susceptibility

· In interior, has significant impact on species composition with decrease in Douglas-firs and replacement with other species

· On coast, may result in conversion to more tolerant species such as cedar or hardwoods

· Affects volume

Impact of Phellinus

· Mortality greater in secondgrowth stands with increased losses projected for third growth stands

· Is a relationship between vigour and susceptibility

· Affects volume

· Reduction in growth and yield

Impact of Tomentosus

· May affect species composition by reducing spruce component of stands but this is not proven

· Decrease in growth and yield

· Is a relationship between vigour and susceptibility

· Likelihood of infection increases with age

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