FRST 351 - Forest Pathology

Terms & Concepts

What follows is a guide for what you are responsible to know.  Actual questions on quizzes & tests will vary.

Introduction to Forest Pathology

Some terms:

• parasite vs. pathogen vs. disease vs. injury

• epidemiology, phytoplane (community)

• symbiot vs. saprophyte vs. parasite (obligate & facultative)

• signs vs. symptoms

• necrotic, atrophic, hypertrophic, lesion, chlorotic, resinosus, broom

• biotic vs. abiotic vs. antibiotic

A sample of some discussion topics

• Describe the attributes of a healthy forest

• Differentiate between endemic and epidemic (scale of disturbance)

• In general terms, how do we manage for a healthy forest

• Discuss how diseases affect diversity and how diversity affects disease

• Discuss how differing management goals (e.g. timber vs. recreation) affect management of forest diseases

• Describe the disease triangle and how it relates to management

Fungi Basics

Some terms:

• hypha, septum, mycelium, chitin

• basidium, ascus, hymenium, spores

• sexual, asexual

• haploid, dikaryon, diploid

• taxonomy vs. nomenclature

A sample of some discussion topics

• Describe the structure and life requirements for fungi

• distinguish between the different roles they play (saprophyte, parasite, etc.)

• Distinguish between the groups of fungi (oomycetes, zygomecetes, basidiomycetes, ascomycetes & deuteromycetes) and provide a forestry example for each

Wood Decay

Some terms:

• rots: brown, white

• rots: true heart, wound entry (primary & secondary) and sap

• rots: top, trunk, butt, root

• wood structure: cellulose, hemicellulose, lignin, extractives

• enzymes: endo- vs. exo-cellulase, lignase, (H₂O₂ & iron)

• incipient vs. advanced decay vs. zone lines

• selective delignification (bio-pulping)

• CODIT (reaction = walls 1-3 & barrier = wall 4)

• resupinate vs. shelf conk

• wound vs. scar vs. gouge

• damage criteria for FG tree ("Christams tree size") and for partial harvest ("mature tree size")

A sample of some discussion topics

• Describe host defence (against the dark arts) mechanisms for decay: constituent, induced & indirect (cork, toxins, resin ...)

• Discuss implications of wounds and decay for forest management ( e.g. tree species & pathological rotation age / shelf-life of dead standing trees / wound size)

• Briefly describe factors to be considered for partial harvest and decay

Root Disease

Diseases studied: DRL, DRA, DRT, DRN, DRB, DRR (and be able to recognize the Latin name)

Some terms:

• antagonism vs. mycostasis

• diffuse disease centre

• ectotrophic vs. endotrophic mycelium

• inoculum potential vs. flare-up

• quiescent vs. active infection

• rhizomorph, basal resinosus

• stumping vs. push-over harvest

• root ball, chimney

• bridge tree removal

• generic symptoms

A sample of some discussion topics

• Describe the basic structure of roots and the soil environment in which roots live

• Differentiate (at a basic level) between the 4 groups of root fungi

• As a root rot travels along the surface of the root (thru' the mineral soil (ABC) and the forest floor (LFH)) and as it infects the various root tissues it will encounter several "difficulties" (mycostasis and tree defenses).  Describe these "difficulties" and be specific with where they are encountered (i.e. ABC vs LFH layers ... live vs dead tissue, bark vs wood)

• Outline the 5 steps for managing root diseases

• Differentiate between hazard & risk

• Outline root rot survey options (sketch map, line intersection, strip - transect, pixel & stump top)

• Briefly describe the factors to consider for future risk to stand

• In general terms, describe the management options at harvest/regen time and at FG/JS time for the diseases studied

• For each of the diseases studied:

  • describe the impact/damage of the disease

  • list susceptible hosts and alternate ('resistant') species

  • describe infection & spread

  • describe the diagnostic signs & symptoms

  • list the survey type(s) likely to be used

  • describe disease-specific management options at harvest / regen time and at FG / JS time

Wilts & Cankers

Diseases studied: Dutch Elm Disease, Atropellis, Chestnut Blight (Hypoxylon)

• origin of DED and its spread

• cause of death

• mechanism for spread

• what has DED got to do with the environmental revolution of the 1960's

• signs & symptoms

• what are the 10 management tactics for DED (state each and provide reason / justification)

+++++++++++++++++ Midterm 1 above +++++++++++++++++

Some terms:

• cankers: diffuse, annual & perennial

• cork cambium (=phellogen) vs. cork (= phellum) vs. phelloderm (draw and label a diagram of bark)

• Periderm (periderm1, periderm2 = cork + cork cambium + phelloderm)

A sample of some discussion topics

• Describe host resistance reaction (periderm/ cork formation) to canker infection

• Very briefly outline the significance/impact of the following cankers: Hypoxylon mammatum, Diaporthe (Phomopsis) lokoyae, Cryphonectria parasitica

• Describe tree resistance (tree age & tissue age) to Atropellis canker

• For each of the diseases studied in some detail (Atropellis canker & Chestnut Blight):

  • describe the impact/importance of the disease

  • list susceptible hosts species

  • describe the signs & symptoms

  • detail management options

Stem Rusts

Diseases studied: White Pine Blister Rust, Comandra (& Stalactiform) Rust, Western Gall Rust    

Some terms:

• pycniospore (=spermatia), aeciospore, urediniospore, teliospore, basidiospore

• wave year

• lethal vs. non-lethal canker vs. threatening (= treatable)

A sample of some discussion topics

• Draw and label a basic diagram that depicts the life cycle of White Pine Blister Rust and relate your knowledge of the biology of this disease to viable management options

• For each of the diseases studied:

  • describe the impact/importance of the disease

  • list susceptible hosts species

  • describe the signs & symptoms

  • detail management options

Foliar Disease & Broom Rusts

Some terms:

• blight vs. cast

• phytoplane community

• foliar rust vs. broom rust

• systemic infection

A sample of some discussion topics

• Compare the impact of defoliation of deciduous (broadleaf) vs. evergreen (conifer) trees

• Describe the reason why DFS (red band) is now a problem in BC and the suggested mgmt tactics

• Describe the factors that affect the variation in foliar disease incidence (i.e. why do we get periodic outbreaks while much of the time a foliar disease may be very hard to find?)

• List 4 foliar diseases, 1 broom rust and 1 foliar rust that are common to BC; provide the primary hosts; and describe the signs & symptoms

Cone/Seed & Seedling

Diseases studied: cone rusts, damping-off, seedling storage molds (Botrytis)

Some terms:

• damping-off

A sample of some discussion topics

• Describe how cone & seed diseases are "managed" w.r.t. cone collections

• Describe how to minimize losses from Botrytis

Dwarf Mistletoe

Diseases studied: DMx: hemlock & lodgepole pine, (Douglas-fir & Larch)

Some terms:

• broom, aerial shoot, basal cup, sinkers, cortical strands

A sample of some discussion topics

• Draw and label a diagram that depicts the life cycle of dwarf mistletoe

• Describe the rate(s) of spread and intensification of dwarf mistletoe

• Some of the management recommendations (especially for juvenile spacing) for dwarf mistletoe appear to be contradictory - discuss this issue.

• For hemlock and lodgepole pine dwarf mistletoes:

  • describe the impact/importance of the disease

  • list susceptible hosts species

  • describe the signs & symptoms

  • detail management options (be able to describe general options as well as those specific to DMH and DMP)

Abiotic Agents

Agents studied: cold, heat, drought, wind, salt, acid rain

Some terms:

• red belt, branch flagging, winter drying, sunscald

• dormancy vs. frost hardiness

• inter-cellular vs. intracellular

• ring shake vs. ring rot vs. red belt

A sample of some discussion topics

• Describe factors that affect frost/heat hardiness of a tree

• Describe the environmental factors that contribute to the amount of damage from excessive heat / cold

• Describe the types of damage caused by low temperatures (e.g. frost crack, red belt, frost heave, ring shake, ring rot, etc.)

• Describe why eastern Canada has "a problem" with acid rain, while it appears that BC does not

Declines

Some terms:

• factors: predisposing, inciting, contributing

• dieback, decline, Waldsterben

A sample of some discussion topics

• Describe the factors that culminate in a forest decline

• Have acid rain and/or global warming contributed to forest declines?  Explain

Wildlife Damage

Agents studied: deer/elk/moose, squirrel, rabbit/hare, porcupine, bear, voles

Some terms:

• clip, girdle, browse

A sample of some discussion topics

• Describe the options for minimizing deer browse

• For the agents studied: describe the preferred tree host(s) (species & size, typical geographic location in BC (north-mid coast, s. interior, n. interior), and the symptoms (damage)

Diagnostics, Assessment & Management

Some terms:

• identification vs. diagnosis

• incidence vs. severity vs. intensity

• hazard vs. risk

A sample of some discussion topics

• Describe how the spatial distribution of a disease can affect management

• Discuss the difficulty in assessing timber volume losses/impact due to disease

• In theory we could virtually eliminate the losses from dwarf mistletoe in one rotation - explain why this will not happen

• List in descending order (biggest first) the agents (dwarf mistletoe, decay, root disease) responsible for timber loss - will the order likely change over time?

• Describe how hazard and risk influence management decisions (e.g. there is potentially a very high hazard (consequence) if disease Ru occurs, however, there is a very low risk (probability) that it will occur - will this situation affect management decisions?)

  Since Sep/08