Forest Insect and Disease Survey; Ontario, 1965 - NFIS

Injury Due to Changing Water Levels
B 12
High water in spring followed by drought conditions in summer appears to have
caused high mortality of red and white pine in several young plantations in the Lake
Simcoe District. High water in the spring presumably killed the original root
system forcing new roots to grow further up the root collar. These roots were very
shallow, one inch or less and were not able to withstand summer temperatures,
particularly where water levels were low.
For the second consecutive year low water levels caused severe browning, loss
of vigour and light tree mortality in the Bruce Peninsula and on shoreline trees
as far south as Goderich. The condition was most evident in clumps of eastern white
cedar, white spruce and tamarack.
Frost Injury
For the second consecutive year late spring frosts severely damaged buds and
new growth of a wide variety of deciduous and evergreen trees (see photographs).
Damage was usually most severe in localized low-lying areas. Red oak, white oak and
white ash were the most seriously affected deciduous hosts and moderate and severe
bud damage occurred in white spruce, Norway spruce, fir and European larch at many
points in the region.
Leaf Scorch
This physiogenic disease continued to be very prominent in the region in 1965.
Premature discolouration and leaf drop was most prevalent on deciduous trees along
older paved highways. Although it is felt that this disease is induced by several
other conditions such as high temperatures and drying winds, it would appear that
excessive use of salt in controlling snow and ice conditions is a major contributor.
This supposition is borne out through surveys and observations on secondary roads
where smaller quantities of salt are used and the disease is much less severe.
TABLE 8
Other Noteworthy Diseases in the Southwestern Forest Region
in 1965
Organism Host Remarks
Apiosporina collinsii
(Schw.) Van Hohnel
Aureobasidium pullulans
(deBary) Arnaud
Camarosporium robiniae
(Westd.) Sacc.
Chrysomyxa led!
de Bary and C.
ledicola
Coleosporium asterum
(Diet,) Syd.
Se
wP, rP,
wS
Hon
wS
jP, rP
Cankers on single branches and
blackening of leaves of two
infected trees in Saugeen Twp.
Common in Lake Simcoe District.
Heavy infection in hedgerow near
Garnet in Walpole Twp., 2i miles
NE of point where disease was
first found in Canada in 1961.
Heavy foliar infection associated
with dwarf mistletoe at Wasaga.
Heavy infections in plantations in
Melancthon and Grantham twps.
Light infections common elsewhere.