FINAL REVIEW: Dwarf Mistletoe

Question 1

How many years does it take dwarf mistletoe to produce its own fruit?

Answer 1

6 years. Same for all mistletoes

Question 2

LIfe History and Characteristics of Dwarf Mistletoe

what are the main natural regulators?

Answer 2

• Obligate Parasite
• Seeds explosively eject (up to 15m)
• takes 6 years for new plants to produce seeds
• small regeneration can be infected, but generally infections are not noticeable until trees are 2 or 3m
• each of the 4 mistletoe species has secondary hosts
• main natural environmental regulators are stand replacement fire, forest succession, and establishment of mixed species

Question 3

what are the 4 species of dwarf mistletoe and their hosts?

Answer 3

• Arceuthobium americanum (lodgepole pine): Pl, Py interior
• A. tsugense (hemlock): Hw coastal
• A. laricis (larch): L, B, Pl interior
• A. douglasii (douglas fir): F, B southern interior

Question 4

Describe Hawksworth Rating System

Answer 4

Step One:

Divide live crown into thirds

Step Two:

Rate each third seperately. Each third should be given a rating of:

0=no visible infections

1=light infection (1/2 or less of total number of branches in third infected)

2=heavy infection (more than 1/2 total number of branches in third infected)

Step Three:

Add ratings to obtain rating for total tree

**See diagram**

Question 5

Name the 3 direct effects of dwarf mistletoe infection on stems

Answer 5

Energy of disease/infection is directly taking energy from the tree

1. Reduced height and diameter growth
2. Reduced lumber recovery (tree grows ‘wonkier’)
3. Eventual mortality (slow process)

Question 6

What are the indirect effects of larch dwarf mistletoe

Answer 6

• Host is more susceptible to other disease
• branches break off, creating entry points for decay
• stem swellings also create entry points

Question 7

Five forest health related reasons Lw is an increasingly preferred species for regen and leave trees in the West Koots

Answer 7

1. Adapted to climate change
2. Windfirm
3. Fire resistant
4. Seral species-good early growth
5. Preferred species to regenerate

Question 8

3 Reasons Lw is important in the West Koots (non-forest health related)

Answer 8

1. Monetary value
2. Biodiversity
3. Has really good wildlife tree potential (perfect nest trees)

Question 9

mgmt options in SP’s for mistletoe

Answer 9

• even aged, clearcut: cut all residual host species; residual non-host species as border trees
• even aged, seed tree: leave non host tree species; prefer seed tres with no infection (<4 rating); girdle or remove infected seed trees if utilized once regen is established
• even aged, shelterwood: non host tree species as residuals; little or no infection for overstorey; remove all advanced regen over 2m tall for DMH if overstorey infected
• uneven aged, shelterwood and uneven aged selection: in stands where susceptible trees comprise >50% of the total stems, and where greater than 20% of susceptible overstorey trees are noticeably infected, not recommended.
• reserves: lay out reserve “Islands” to minimize spread

Question 10

stand mgmt prescriptions for mistletoe

Answer 10

• in dense stands the rate of spread is low, and shading can eliminate lower branch infections as branches die
• density reduction during pre commercial and commercial thinning can increase rates of spread and damage from dwarf mistlotoe
• in older trees infections may lose their aerial shoots and become quiescent. INcreases in light can reactivate these infections
• GUidelines: whenever possible remove or girdle all infected trees; if adjacent timber or residuals are infected, leave a non-host buffer