WIlts

Question 1

How do wilts spread?

Answer 1

• insect vectors and or root contact

- fungus invades xylem and tree reacts with gums

Question 2

How do wilts kill?

Answer 2

• Trees own defence mechanisms (gums and tyloses plug up vessels)
• Fungal mycelium generates toxins

Question 3

What is the biggest baddest wilt?

Answer 3

Dutch elm disease (DED)

• ophistoma ulmi and
• novo ulmi (more virulent and newly discovered)

Question 4

Where did DED originate?

Answer 4

The Orient
-introduced to north america via green lumber with bark beetles under bark. (not kiln dried). modern transport is fast enough to deliver beetles to NA as they matured.

Question 5

What are the hosts and range of DED?

Answer 5

Global scale.

• West asia, europe, US, Canada
• Not in alberta or BC yet due to intensive protection by alberta.

Question 6

Signs and symptoms of DED?

Answer 6

• Branches (leaves) wilt early in summer
• Branch dieback
• Purple black streak in sapwood (just like DRB)
• Beetle activity under bark (parent tunnel with radiating grub tunnels)

Question 7

How is DED different than DRB signs symptoms

Answer 7

• Branch dieback in dutch elm because beetles attack base of tree in black stain
• wilting of leaves in elm while needles cannot wilt and just turn red and fall off.

Question 8

What are some ways to manage for DED?

Answer 8

• constant monitoring and rapid delimbing
• pruning (if less than 5% of crown infected)
• if more than 5%, sanitation of infected tree.
• trenching to isolate tree roots
• spray for beetle
• kiln dry wood before transport
• preventative fungicide injection (1-3 year protection)
• vaccine injection (annually)
• Trap trees (infected trees injected with herbicide and bark dies too fast for beetle to complete lifecycle)

Question 9

How would you manage for a boulevard of DED
vs a single big elm
vs a park with many elm
vs a natural elm forest?

Answer 9

Boulveard:
Trenching and maybe fungicide injection + Pheremone traps + monitor and rapid pruning.
Single Tree:
Sanitation or perhaps annual vaccine or fungicide injection + Traps + monitor and rapid pruning.
Elm heavy park: Monitoring, Traps, spray for beetle, trap trees, sanitation
Forest: Breed for resistance, Trap trees/traps, monitoring and sanitation.

Question 10

What type of disease are wilts classified as?

what type of fungi are they?

Answer 10

• a “hardwood” disease

- ascomycetes