Definitions Flashcards
Define epidemiology
the study of the patterns, causes and effects of health and disease conditions in defined populations
Define Direct control(As related to MPB)
key principles?
Treatments aimed at reducing beetle populations. Considered a reactive approach because it is undertaken after MPB caused tree morality has already been observed. Key principles in applications are the timing and throughness of detection and treatment. Incomplete strategy as it's fairly useless once MPB has hit epidemic levels Tactics include: Burning Mechanical Treatments Sanitation Logging Chemical Tactics Semiochemical Tactics
Describe burning as a direct control tactic for MPB
intent is to burn standing infested trees to kill MPB broods
high fire intensity results in significant mortality, but difficult to control high intensity fires
Only a valuable tactic in remote locations or areas where other options aren’t permitted or practical
Describe mechanical treatments as a direct control for MPB
DEBARKING: intent is to remove bark from trees before beetles complete development
Awkward and unreliable strategy, many attempts made with various techniques
FELLING WITHOUT HARVESTING: intent is to cause extensive brood mortality by exposing them to drying during hot, droughty conditions
Not effective or practical because bark temps need to be 43°C for several hours and rolled daily
SINGLE TREE FELLING: Where economically feasible, individual infested trees are harvested and transported to mills where beetle broods are killed during processing.
If single trees uneconomic to harvest, can be felled, cut into manageable pieces, piled over the stump and burned
Achieving a thorough, high intensity burn is vital
Describe sanitation logging as a direct control of MPB
Block harvesting used to control populations where infestations encompass whole stands or groups of stands
Most common tactic in BC
Limited by:
available road access(important! won’t be as much as issue in 50 years);
land tenure considerations;
non timber forest values;
timber markets;
milling logistics(timber must be milled before new adults emerge and disperse although this limitation can be largely overcome by sprinkling log decks with or submerging them in water);
Pl component within stand is sparse (15% in stand), difficult to address when you’re dealing with incremental losses
Describe Chemical Tactics as a direct control of MPB
Considerable effort has been made to develop insecticides, focusing on 2 broad categories:
-Chemicals applied to bark over bole of the tree: relatively ineffective given MPB spends most of its life cycle under the bark and is not as responsive to the application of broadcast insecticides as other damage agents such as defoliators
Downside to Kootenay mix-economically you can’t address it (re-sanitation) because yo’ure only focusing on taking out the Pl
-Chemicals injected into tree: Need to be applied within 3 weeks of initial attack to be effective because MPB tunneling combined with blue stain colonization of the sapwood stifles the applied chemical from translocating wthin the stem and contacting the beetles
Effectiveness limited by concerns over toxicity of the applied substances to workers and their environment
Only one registered pesticide (MMSA)used in Canada and not known if it’s use will continue
Define semiochemicals
Semiochemicals: signal bearing chemicals involved in interactions among organisms
Define Pheremones:
substances emitted by an organism that cause a specific reaction in a receiving organism of the same species
Kairomones:
Substances that evoke in the receiver a reaction that favours the reciever but not the emitter
Describe Semiochemical Tactics as a direct control of MPB(2Strategies)
- Targets aggregation behaviour in two specific pheromones and one specific kairomone
- Targets anti-aggregation behaviour in one specific pheromone(redirecting)
These semiochemicals have been developed into commercial devices intended to focus/concentrate(aggregate) beetle pop’s in stands or deter/redirect(anti-aggregate) them from stands
Usually used with other direct control strategies because semiochemical application does not cause direct MPB mortality
4 examples of semiochemical tactics used with other direct control strategies
- bait trees with aggregation pheromons around the edge of a small infestation that had been treated with an insecticide
- apply agg. pheromones to residual stems as a “post logging mop up” to ensure that remaining beetles don’t disperse and can be easily located for follow up treatments
- “containment and concentration”. infested stands are inundated with agg. semiochemicals, allowing infestations to intensify but not expand, helping secure realistic plans for salvage operations
- might be possible to use agg. and anti-agg. pheromones simultaneously by pushing them out of high value areas and into adjacent areas slated for treatment
Define indirect control as a tactic for MPB
Treatments aimed at increasing stand vigor or reducing the amount and concentration of susceptible stands. AKA Preventative Mgmt or Proactive Mgmt. Considered pro active because it is primarily done before an outbreak develops. Key principles in application are the consistent use of well-planned forestry practices during periods when MPB pops are at endemic levels
Resistance (Cruickshank definition)
Plant mechanism that limits the pathogen-measured by a reduction in pathogen offspring or reduction in plant damage-often reduces plant growth
Define Heart Rot
Decay in living trees. Develops primarily in heartwood or inner wood
Define Sap Rot
rot that occurs in sapwood, not saprobic decay
