February, ’18] 
PRIMM: EUROPEAN POPLAR CANKER 
129 
Java. 8 
Jamaica. 7 
Mexico. 7 
Antigua, B. W. 1. 6 
Italy. 6 
New Zealand. 6 
Bermuda. 5 
Costa Rica. 5 
Egypt. 5 
Straits Settlements. 5 
Algeria. 4 
Canal Zone. 4 
Eucador. 4 
Haiti. 4 
Panama. 4 
Paraguay. 4 
Spain. 4 
Azores. 3 
Bahama Islands. 3 
Honduras. 3 
Peru. 3 
Saint Lucia, West Indies. 3 
Scotland. 3 
British Guiana. 2 
Canada. 2 
Denmark. 2 
Palestine. 2 
Porto Rico. 2 
South Africa. 2 
Virgin Islands. 2 
Angola, Africa. 1 
Canary Islands. 1 
Ceylon. 1 
Dominica, B. W. 1. 1 
Dominican Republic. 1 
Madeira. 1 
Mauritius. 1 
Natal. 1 
Newfoundland. 1 
Nicaragua. 1 
Northern Nigeria. 1 
Portugal. 1 
Reunion. 1 
Russia. 1 
Turk’s Islands. 1 
THE EUROPEAN POPLAR CANKER IN THE VICINITY OF 
PHILADELPHIA, PENNSYLVANIA 
By James K. Primm, 
Bureau of Zoology, Harrisburg, Pa. 
While inspecting the nurseries of Pennsylvania in the summer of 
1917 a good opportunity was afforded to become acquainted with the 
disease known as European poplar canker (Dothichiza populea). 
In only one of the numerous nurseries growing poplar trees within a 
radius of thirty-five miles of Philadelphia this fungous had not become 
well established. Trees of all ages were attacked, one- and two-year- 
old stock much less seriously, however, than trees three or four years 
of age. This apparently higher resistance in young trees, noted 
especially in Carolina poplars, is modified by the fact that younger 
trees are damaged less by storms and have not been topped or pruned 
to any extent. The degree of infection varied from single isolated 
twig cankers to numerous and confluent trunk cankers. The most 
virulent attacks were on trees that had been pruned close to the trunk 
to a height of three to five feet. 
The resistance of young trees is even more marked by the slight 
percentage found to be affected when comparison is made with older 
stock. In one-year stock only 2 or 3 per cent were found to be infected. 
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