WIlts Flashcards
How do wilts spread?
- insect vectors and or root contact
- fungus invades xylem and tree reacts with gums
How do wilts kill?
- Trees own defence mechanisms (gums and tyloses plug up vessels)
- Fungal mycelium generates toxins
What is the biggest baddest wilt?
Dutch elm disease (DED)
- ophistoma ulmi and
- novo ulmi (more virulent and newly discovered)
Where did DED originate?
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.
What are the hosts and range of DED?
Global scale.
- West asia, europe, US, Canada
- Not in alberta or BC yet due to intensive protection by alberta.
Signs and symptoms of DED?
- 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)
How is DED different than DRB signs symptoms
- 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.
What are some ways to manage for DED?
- 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)
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?
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.
What type of disease are wilts classified as?
what type of fungi are they?
- a “hardwood” disease
- ascomycetes