in the south-west part of the infestation, accompanied by an extension in the 

 north-east resulted in a slight north-easterly shift in location. 



Several pockets of light and medium spruce budworm infestation, largely 

 on white-spruce trees, occurred in the Lake Simcoe, Lake Huron and Lake Erie 

 Districts of southern Ontario. 



Larch sawfly populations across northern Ontario declined, and despite 

 some pockets of heavy infestation, notably across central Geraldton and in the 

 Sault Ste. Marie District, were at their lowest point of any year during the past 

 decade. In southern Ontario population levels were about the same as in 1960, 

 with infestations being reported from all districts. A number of valuable European 

 larch plantations were severely defoliated, necessitating control action. 



The European pine sawfly continued to spread eastward in southern Ontario 

 at its usual rate, and now extends over south-western Ontario as far east as a 

 line from Penetanguishene to Leaside, with an extension along the shore of Lake 

 Ontario to Whitby. In addition, it has been found in three widely spaced spot 

 infestations to the east at Orono, near Vernonville and Belleville. 



The current outbreak of the forest tent caterpillar became apparent first in 

 1960 as scattered pockets of defoliation in the Kenora, Sioux Lookout and Sud- 

 bury Districts. The Sudbury infestation almost disappeared in 1961 due to un- 

 favourable environmental factors, but light infestations appeared in the Parry 

 Sound and Pembroke Districts. 



The eastern tent caterpillar, which is conspicuous by the tent it makes on 

 wild cherry and apple trees along roadsides, showed greatly increased populations 

 in all districts within the insects range, that is, from Sault Ste. Marie to North 

 Bay and throughout southern Ontario. In the Parry Sound, Pembroke, Lake 

 Simcoe, Lake Huron, Lindsay and Tweed Districts where infestations were heav- 

 iest, larvae tended to migrate from defoliated cherry trees to other hardwood 

 species. 



The severe infestation of the jack^pine budworm in the north-central' part 

 of the Fort Frances District subsided in 1961, but new infestations appeared 

 in other parts of the Fort Frances and Kenora Districts, and at scattered points 

 in south-western Ontario in the Lake Huron and Lake Erie Districts where the 

 insect also attacks Scots-pine plantations. 



In 1961 the birch skeletonizer caused sever browning of white birch foliage 

 from Sault Ste. Marie to North Bay, and throughout most of southern Ontario. 

 Although the outward damage is spectacular in appearance, it occurs in late 

 summer when tree growth is about finished, and therefore does not cause ap- 

 preciable permanent injury to the trees. 



The major tree disease in Ontario is the white-pine blister rust, which is 

 well-distributed over most of the range of white pine, although increased inci- 

 dence of the disease was observed in 1961 in the Chapleau, Gogama and Swa- 

 stika Districts. The intensity of the disease varies locally, depending on climate, 

 topography and the abundance of the alternate host plants. 



The Dutch elm disease again extended its known distribution, and has 

 now been found in all counties of southern Ontario and as far north as South 

 River in the Parry Sound District and Deep River in the Pembroke District. 



In 1961 considerable interest was centered on a dieback condition of balsam 

 fir in Guilfoyle Twp., Kapuskasing District. Surveys indicated that between 5 

 and 10% of the balsam in the upland mixed wood type was dead or dying from 

 disease. The disease is conspicuous by the fact that whole crowns of trees turns 

 reddish-brown quite suddenly. Research into insects and pathogens as possible 

 causes is now underway. 



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