Forest Insect and Disease Survey; Ontario, 1965 - NFIS

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TABLE 12
Summary of Leaf-folding Sawfly Counts in Lake Simcoe District
in 1964 and 1965
Note; Counts were based on the examination on 100 leaves of four trees at each
location.
,===========
Location Tree Number of folds per hundred leaves
Township species 1 1 6
Matchedash tA 2 22
Orillia tA 1 4
Albion tk 44 31
Tosorontio tA 7 24
W. Gwillimbury cPo 53
Medonte tA 98
June Beetle, phyllophaga sp.
Although little root damage by larvae of this insect was recorded in 1965 heavy
adult populations which emerged from the soil in May and June caused moderate to
severe defoliation of a wide variety of deciduous trees in the district. In Mara
Township, heavy adult feeding over a prolonged period resulted in mortality of a
few young open-grown ash trees (see photograph). Heavy adult flight occurring at
3-year intervals usually results in severe larval damage to the roots of ground
vegetation and young trees the following summer. Control measures are advised in
1966 where second-year white grubs are common, especially where the planting of
trees is contemplated in sodded fields.
White-pine Weevil, Pissodes strobi Peck
The incidence of leader damage caused by thi weevil increased at three sample
points and declined at six points in 1965 (Table 19). The most notable decline in
leader damage occurred at a point in Matchedash where nine per cent of regeneration
white pine trees were attacked in 1965 compared with 36 per cent in 1964.
TABLE 19
Summary of Leader Damage by the White-pine Weevil
in Lake Simcoe District in 1964 and 1965
Location
townshi
Tree
s ecies
Per cent of trees weevilled
1
Whitchurch wP 30 54
Matchedash wP 36 9
Essa wP 71 30
Orillia wP 18 11
Gwillimbury wP 35 65
Oro wP 26 13
Whitchurch nS 5 10
Vespra nS 44 30
Innisfil
King
wP
wP 33
38
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