Post on 15-Aug-2020
White pine blister rust on pine
History of white pine blister rust • First recorded in Europe from the Baltic region in 1854
• By 1900 it widespread across Europe - rapid spread by forest tree nurseries
• Introduced into Eastern North America probably by 1898 on nursery stock from Europe, definitively recorded in Geneva New York and seven other states by 1900
• Discovered in Vancouver BC in 1921 on Ribes nigra and young exotic pines. - by 1922 it was found widely in BC and the Northern Cascades of Washington state; entire epidemic appears to have originated from a single batch of 1,000 seedling imported from France
Control measured tried
• Elimination of Ribes species • Breeding for resistance
(vertical and horizontal)
Bro Kinloch Forest genetist who has worked on resistance of Sugar pine
Distribution of the “big R” gene in sugar pine
Horizontal resistance on a young sugar pine at Happy Camp nursery
Effect of White pine blister rust (& selective logging) on forest composition in Montana
What is the fate of white pines in Western North America
• Most species will probably not become extinct
• But they will become much less common and more restricted in habitat
• Many secondary effect on wildlife and forest health are possible
Dutch Elm disease Ophiostoma ulmi
• Deadly beetle vectored disease of Elm
• All European and North American Elms are susceptable
Lifecycle of Dutch Elm disease
Lifecycle of Dutch Elm disease
Dutch Elm disease effects
Dutch Elm disease symptoms on wood
Scolytus mutistriatus
Ophiostomatales, Ophiostoma Mitotic “graphium” state
Meiotic Ophiostoma state
History of Dutch elm disease • Appeared in France, Belgium, and Germany between 1918-1921
• Arrival in Eastern US in late 20s, established in New York and effecting 5500 sq miles by 1940
• strain transported to Ohio 1928 via diseased logs
• New epidemics in Europe, Aggressive strains recognized in Europe 1971
• Origin of disease remains unknown to this day!
Distribution of “aggressive strains” in Europe. now known to be a new species, O. nova-ulmi
Control measures tried
• Beetle control through “sanitation” • Chemical control on prize trees • Breeding for resistance • All of the above have only been applied to
city settings; the forest trees are now gone.
Disease progress curves for Dutch elm disease in Midwestern and Eastern cities
Chestnut blight�Cryphonectria parasitica
• Primary host: Chestnuts • Effect: kills above ground portion of trees • Spread by wind and by animals
Chestnut blight effects
Chestnut blight effects
Cryphonectria
Stroma with perithecia and pycnidia
Cryphonectria
A cirrhus of mitospores or conidia
Chestnut blight distribution
Control measures tried
• Breeding for resistance • Virus mediated hypovirulence
Fungi and Virus
Castenia - Cryphonectria - Hypovirulence Virus Nuss and Colleagues, Maryland
Pitch Canker Fusarium circinatum
• Hosts - all pines tested and Douglas-fir • Kills branches and ultimately trees • May be beetle vectored
Pitch Canker - Fusarium circinatum
Home Ranch site at Pt. Reyes
Pitch Canker • first seen in California in1986 near Santa Cruz • Now found from San Diego to Mendocino • Devastating effect on Monterey pine throughout range • Also spread to Japan and South Africa • Host range known to be much broader • Origin of the disease may be Mexico
Sudden Oak Death
• Wide host range • Spread by locally via wind, water, soil • Probably spread across continents and
within California via the nursery industry (Rhododendron movement)
• Origin of disease still unknown • Ultimate impact of disease to be determine
Sudden Oak death - Phytophthora ramorum At China camp State park, Marin Co.
Other examples • Phytophthora cinnamomi Australian forests • Phytophthora lateralis on Port Orford Cedar • Dogwood Anthracnose - Discula destructiva • Butternut canker - Sirococcus clavigignenti-
juglandacearum • Beech bark disease - Eastern NA • Puccinia psidii - guava rust
Some general rules • The problem is clearly international and growing • Consequences of introductions can be catastrophic • Once an introduction happens little can be done • The diseases are often unknown or of minor importance in
their native range • Scientific names of pathogens are deceiving.
What can we do?
• Educate the public about the dangers of moving plant material and soil
• International restrictions on the movement of living plants and green logs - this is an uphill battle that will take tremendous political pressure.