Root Disease (DRL) biology

Question 1

What are the ecological effects of DRL?

Answer 1

• Creates diversity in stand
• CWD generated
• Wildlife habitat generated
• Can coexist with other root disease

Question 2

What is the geographic range of DRL?

Answer 2

Southern BC wherever Fd exist.

Question 3

Which trees are most susceptible to phellinus?

Answer 3

Fd, Ba, Bg, Hm

Question 4

What trees are tolerant to DRL? Resistant?

Answer 4

Tolerant: Pines
Resistant: Cw, Hardwoods

Question 5

Infection method of DRL?

Answer 5

Root grafting only

No spreading by spores.

Question 6

What are the two forms of DRL?

Answer 6

P weirii (Cw)
P sulphurescens (Fd)

Question 7

What are the hosts of DRL?

Answer 7

Susceptible: Fd, Ba, Bg, Hm
Tolerant: Pines
Resistant: Hardwoods, Cw

Question 8

Define ectotrophic mycelium

Answer 8

mycelium on root surface… DRL

Question 9

What is the rate of DRL spread dependant on?

Answer 9

Stand composition (% susc. host)
Soil conditions (Loamy soils, Fresh/moist optimal spread)
Innoculum potential decreases with time (sharp drop after 20 years).

Question 10

Define innoculum potential

Answer 10

The ability of a fungus to infect. Decreases with time

Question 11

Why does innoculum potential decrease over time?

Answer 11

Antagonism (mycostasis)

Time exhausts available food supply

Question 12

What is the typical volume loss for heavy DRL?

Answer 12

40-70% loss by rotation age

Question 13

How do trees usually die from DRL?

How early can mortality start?

Answer 13

Windthrow and girdling
mortality starts after 10-20 years
older trees die within 10 yeas of symptoms

Question 14

2 reasons for reduced growth

Answer 14

• Not as much roots due to attack.

- Must invest energy into root growth.

Question 15

What are the signs and symptoms of DRL? (6)

Answer 15

• reduced growth
• thin crown
• chlorotic
• stress cone crop
• disease centres (diffused centers)
• Red stain on top of recently dead stump

Question 16

What colour would you expect the ectotrophic mycelium of DRL to be?

Answer 16

• White in mineral soil

- Brown and crusty if exposed

Question 17

Inside tree, what are DRLs characteristics?

Answer 17

setal hyphae (brown and fuzzy)

Question 18

What does resupinate mean?

Answer 18

Refers to “flat” growth along substrate.

Question 19

What physical signs would you look for to assess for DRL when you see fallen trees?

Answer 19

Root Balls

Criss Cross pattern