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ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 46 



to all pruning wounds, as described in the section "Wound Treat- 

 ment." The bark should not be injured unnecessarily, since the 

 fungus may enter through wounds resulting from injuries. When 

 the branches of affected trees are wet, spores ooze out from can- 

 kers onto the surface of the bark. Pruning at this time should 

 be avoided, since spores may be spread by pruning tools. Spray- 

 ing the low branches and the trunks of affected trees and nearby 

 healthy trees in the spring with organic mercury or copper sul- 

 fate and hydrated lime may help to prevent spread of the dis- 

 ease. The spray materials are the same as those for tip blight of 

 spruce (Table 1) ; three or four applications of spray at 2- to 3- 

 week intervals are required. Since, it is believed, weakened trees 

 are susceptible to this disease, feeding to stimulate vigorous 



Fig. 82. — Anthracnose of sycamore frequently causes severe defolia- 

 tion and twig dieback early in the growing season. This type of injury is 

 frequently confused with frost damage. 



