16 
tops. Another striking phenomenon in connection with these 
trees was the unusual production of short shoots at the base of 
the diseased trees. 
It is probable that the primary cause of the death of the birch 
trees is the bronze birch borer. All of the diseased trees were 
found infested with this insect, which has been reported as the 
cause of the destruction of a large number of birch trees, par- 
ticularly in the parks. Associated with the birch borer, however, 
were various fungi which are probably secondary invaders of the 
dead or dying portions of the trees. 
The fungus which was found to occur with great Feenlariey on 
the small branches of the trees was Cytospora horrida Sacc. 
Numerous canker-like areas were found on many of the 
larger limbs, often adjacent to their attachment to the main stem. 
These cankers were regularly infested with the bronze birch 
borer. In addition, the imperfectly developed fruiting bodies of 
fungi were found on the cankers. 
One tree of the European white birch in the Botanic Garden 
was found to have died and the main trunk and larger limbs 
were badly infected with Melanconium bicolor Nees. The fruit- 
ing bodies of the fungus had protruded through the bark over 
a large portion of the surface of the tree. The tree was about 
four inches in diameter and the main trunk and the larger 
branches, down to one inch in diameter, were extensively cov- 
ered with the fruiting bodies. To some extent, the bronze birch 
borer had also infested this tree and again the insect may have 
been the primary cause of the death of the tree. 
The leaf spot of the sycamore, Gnomonia veneta (Sacc. & 
Speg.) Kleb., was very common, both in the Park and in the 
Botanic Garden, during the latter part of June and the first part 
of July. During this time, a large portion of the leaves on the 
trees were infected and were constantly falling to the ground. 
A few individual trees were practically defoliated, although in 
some cases the damage was not nearly so severe. Due to the 
fact that the sycamore puts out additional leaves rather rapidly, 
the trees practically regained their normal appearance toward 
the end of the summer. While many oaks were found in both 
Park and Garden, this disease was not collected on any of them. 
