White Pine Blister Rust

Question 1

What is the difference between blister rust on stem vs branches?

Answer 1

If on branch no problem, on stem it is lethal.

Question 2

What happens if blister rust girdles a branch?

Answer 2

Kills branch which will kill itself

Question 3

What are the types of cankers?

Answer 3

Lethal: on stem or on branch within 15cm of stem because fungus is active beneath bark. From 15-60cm it will kill tree if not pruned.

Non threatening: more than 60 cm from stem.

Question 4

What does top kill refer to?

Answer 4

If canker high on stem it just kills top.

Question 5

What was a result of blister rust damage?

Answer 5

Wiped out pw as a viable spp. Genetic advancements have improved resistance.

Question 6

What are some important positive silvical characteristics of white pine?

Answer 6

Fast growing
Valuable wood
Resistant to DRL

Question 7

How does age of tree effect resistance?

Answer 7

• Under 20 years old trees are in high danger due to low needles
• over 40 years low danger as needles get higher.

Question 8

What are uridiniospores?

Answer 8

Orange spotting on currents that are designed to build up disease population.

Question 9

What are signs and symptoms on ribes?

Answer 9

• Rust spots on underside of leaf

- brown bristles (telial columns) in late summer

Question 10

What are the signs and symptoms on Pw?

Answer 10

• spindle shaped swelling
• orange spores bursting from bark
• top kill
• red flagging/rodent feeding (sugars)
• diamond shaped spore patch on canker in early stage ( longitudinal growth faster than radial )
• resinosus
• rough Bark

Question 11

Is tree reacting to blister rust?

Answer 11

No, blister rust attracts secondary pathogens like insects and other fungi by attracting sugars to infection.

Question 12

What are the hosts and range of blister rust?

Answer 12

Range of soft 5 needle pines
Introduced to North America in early 1900s

Found on soft pines and currants

Question 13

Is ribies eradication feasible for management?

Answer 13

Effective in east NA and less effective in west but can help at local scale.

Question 14

How is pruning timed and managed?

Answer 14

2 lifts.
First lift: 
Tree height 2m
Prune height 50%
Timing in May/June when spores are visible.

2nd lift:
tree height 4-5m
Prune height 50%

Question 15

FG criteria for blister rust ***

Answer 15

Fails if: canker on stem or canker less than 60 cm from stem on live branch.

Question 16

What to consider if trying to assess blister rust hazard?

Answer 16

• what kind of currant and how much? [ black, high/ red, mod/ swamp, low)
• dry climate is good because delicate Basidiospores dry out faster.
• gullies are dangerous because of moist
• slopes are bad because they put foliage closer to currant

Question 17

Where is the risk the lowest and highest in bc for blister?

Answer 17

Lower risk on dry coast above 1000m

High risk in kootenays

Question 18

Why do we tree breed for for blister rust?

Answer 18

• variation in resistance
• moving trees long distances can cause problems due to seasonal variations but white pine is quite elastic. One breeding program for coast and one for interior.

Question 19

What are the two schools of thought in breeding for rust resistance?

Answer 19

• single (major gene) resistance
• multiple ( minor gene resistance )
• lose needles early
• infected needles drop
• bark reaction ( toxic chemical produced that resists canker )

Question 20

What is the goal of breeding for resistance?

Answer 20

65% resistance (survival rate)

No need to prune resistant stock

Question 21

Management decisions for rust

Answer 21

• mix spp
• genetically resistant stalk
• plant high density
• prune ( 2 lifts to keep branches 2m from ground)
• aim for drier sites if hard pines not an option.

Question 22

What are the benefits of dense stands where blister rust

Answer 22

• ribes shaded out
• lower branches shaded out and self prune sooner
• Lower branches self prune sooner
• some mortality is acceptable if high density
• benefit is only evident after crown closure and time of most concern.

Question 23

What is the infection zone of blister rust?

Answer 23

85% of infection below 2 m

Question 24

What is the lifecycle sequence of white pine blister rust?

Answer 24

Basidiospores 1n
Spermatia 
Aeciospores
Urediniospores
Teliospores 2n