Annual District Reports: Forest Insect and Disease Survey ... - NFIS

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2.1 INTRODUCTION
This report deals with forest insect and disease conditions
throughout the Interlake Section and the western part of the
Southern District of Manitoba extending from the Red River to the
Saskatchewan border. Field surveys were carried out from about mid-May
to October 5, and 464 insect and 37 disease collections were submitted
to the Winnipeg and Saskatoon laboratories respectively. In addition
to general sampling and special collections, the following surveyprojects
were continued: forest tent caterpillar egg-band counts to
forecast population and infestation trends; larch sawfly cocoon collecting
using the larval-drop tray method to determine the incidence of
parasites and disease; sequential sampling of larch sawfly eggs for
population estimates; and larval sampling of the boxelder twig borer.
Approximately 3 hours and minutes of chartered flying were used for
aerial reconnaisance of inaccessible areas in the Interlake section and
to map infestations of the forest tent caterpillar, jack-pine budworm
and larch sawfly. The cooperation and assistance received throughout
the field season from personnel of the Renewable Resources Branch,
Department of Natural Resources is gratefully acknowledged.
The cool, wet weather that prevailed during May and June
favored good tree growth, but foliage and insect development was delayed
about ten days in most areas. The season ended. with light rainfall and
much above average temperatures. The larch sawfly was again the most
widely distributed forest insect occurring in outbreak numbers, but populations
generally remained at the same level as in 1962. The jack-pine
budworm infestation along the Gypsumville, Grand Rapids Highway expanded
and increased in intensity, and the black-headed budworm was more common
in all areas. Relatively-high larval populations of the yellow-headed.
spruce sawfly caused noticeable defoliation of single or small groups
of trees at widely scattered points,- and the infestation of jack-pine
shoot moth, (Eucoma gloriola Hein.) was more widespread. High populations
of adults of the aspen leaf beetle were recorded throughout most
of the District in late May and. June- However, larval populations did not
develop fully and skeletonizing of aspen foliage was patchy and less
severe than expected. The status of the forest tent caterpillar remained
unchanged with main infestations again limited to the Lake St. George.
area in the Interlake section. Populations of the aspen blotch miner
were notably higher in many areas but resultant foliage damage was light.
Several localized infestations of, the fall cankerworm developed in parts
of the District; defoliation was particularly severe along the Red River
in Metropolitan Winnipeg and in field-row plantings in the Lyleton area.
The Most important tree disease condition was continuing
mortality of trembling aspen in prairie "bluffs" in southwestern Manitoba
resulting from the extreme drought of 1961. Spraying with 2 1 4-D for weed
control in field. crops caused notable damage to the shoots and foliage
of Manitoba maple and several other tree species in localized areas
throughout the agricultural sections, and leaf blights of trembling aspen,
balsam poplar and white elm caused some coloration and early leaf-fall in
some parts of the District.