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.