Forest Insect and Disease Survey; Ontario, 1965 - NFIS

C1
STATUS OF TREE DISEASES
Dutch Elm Disease, Ceratocystis ulmi (Buism) C. Moreau
Increases in the incidence of this disease occurred throughout Division 93 in
the southern part of the Parry Sound District. Extensive mortality was observed in
recently infected areas north of Burk Falls, particularly in the townships of Wilson,
Armour, Strong, Paterson, Chapman, Ryerson, and South Himsworth.
In the North Bay District, increases in the number of infected trees were
observed in Papineau, Mattawa and Widdifield townships. Samples of the disease
were collected at North Bay and Sturgeon Falls and near the towns of Field, Noelville,
Warren, and Hagar in 1965.
TABLE 1
Summary of Incidecne of Dutch Elm Disease and Tree Mortality
at Five Points in the South-central Region in 1965
Note: Counts were based on the examination of 100 trees at each point.
Location Av. d.b.h. Per cent infected Per cent infected
(township) in inches trees (living) trees (dead)
Humphrey 15 22 23
Papineau 16 3 5
Mattawan 14 1 3
Widdifield 15 3
Hartland 15 2 1
Needle Rust, Coleosporium asterum (Diet.) Syd.
Heavy infection of red pine foliage by this disease occurred in a red pine
plantation on the north shore of Fletcher Lake, McLintock Township, Parry Sound
District, and in jack pine plantations in French and Widdifield townships in the
North Bay District. Red pine trees in reforested areas in Firstbrook Township,
in the North Bay District, were lightly infected and the rust was observed at
numerous other locations in the region.
White Pine Blister Rust, Cronartium ribicola J. C. Fischer
This disease was found in varying degrees of intensity in all white pine stands
in the region. Pockets of heavy infection occurred along the south shore of the
Pickerel River and in Boulter Township in the Parry Sound District. Branch and
stem mortality caused by the rust occurred commonly around the West Arm of Lake
Nipissing and at numerous other locations in the North Bay District. The incidence
of infection at four plots averaged approximately 33 per cent (Table 2).