DRA

Question 1

What are the susceptible hosts of Armillaria?

Answer 1

Fd, B,S, Hw

Question 2

What are the resistant trees to DRA?

Answer 2

• Lw
• Cw
• Hardwoods

Question 3

What should we remember when using Lw as an alt. spp?

Answer 3

Early mortality due to fast root growth while tree is vulnerable

Question 4

What is the most resistant tree to DRA?

Answer 4

Cw

Question 5

What is something to remember about hardwoods as alt spp?

Answer 5

Resistance decreases as time goes on. Go for a short rotation.

Question 6

What is the difference between Coast vs Interior DRA?

Answer 6

• Interior wet belt - Universally present (Trees are healthier and disease is diffuse)
• Coast - (not significant (mortality up to 15 years))
• Rest of Interior - disease centers evident (1-10 ha)

Question 7

What will decide tree mortality by DRA?

Answer 7

The relative strength of trees will ultimately decide whether DRA can kill them or not.

Question 8

How does armillaria infect trees?

Answer 8

Spores rare, infection via root contact or “rhizomorph”

Question 9

What is the common name for DRA? why?

Answer 9

Shoestring fungus. If roots are close but not touching, DRA creates a bridge to the healthy root.

Question 10

What are the characteristics of DRA mycelium?

Answer 10

Endotrophic mycelium (live in bark/cambium - mycelial fans)

Question 11

What parts of the tree can DRA inhabit?

Answer 11

• Sapwood (CODIT reactions)
• In heartwood when present in large roots
• Operates in all tissues

Question 12

What is the rate of spread of DRA?

Answer 12

about 10cm / year in BC. Has a slower rate of spread than phellinus because it likes to go inside the tree.

Question 13

How does harvesting increase innoculum potential of DRA?

Answer 13

Trees natural defenses are removed and DRA goes into a flare up, gaining strength off the available food that it now does not need to fight for.

Question 14

What is innoculum potential dependent on in DRA?

Answer 14

• Available food increases innoculum potential

- When DRA is battling a tree its innoculum potential decreases

Question 15

Quiescent vs Active DRA

Answer 15

Quiescent disease centers in wetbelt

Active disease centers in the rest of the interior

On the coast the disease centers are active in the juvenile stage but become quiescent as the trees gain strength.

Question 16

What are some damage characteristics of DRA

Answer 16

Same as DRL

• Girdling
• Windbreak (Older) more common
• Windthrow (if roots compromised)
• Reduced increment
• Decay (limited)

Question 17

What is a tell tale sign of DRA

Answer 17

-White mycelial fans under bark

Question 18

What are some diagnostic symptoms of DRA

Answer 18

• white mycelial fan under bark at base of tree.
• Basal resinosus
• Black fuzzy stain at base of tree (feeding on resin)
• clustered mushrooms at base of tree
• Rhizomorph (black) in soil or under bark.

Question 19

What is the Range of armillaria

Answer 19

Range of Fd in BC