44 MAINE AGRICULTURAL EXPERIMENT STATION. 



DISEASES OF SHADE TREES. 



Each year a eonsiderable number of specimens of diseased 

 sugar maple leaves are received the last of June and on through 

 July. Almost invariably these are the result of late frosts, or 

 result from the effects of strong drying winds, associated with 

 bright sunlight, following a period of moist, cloudy weather 

 when the young leaves have been growing rapi^lly and conse- 

 quently are very tender 



Much complaint is received from a leaf-spot of the horse- 

 chestnut. The disease is so common and destructive that it is 

 strongly advised that other species not susceptible to disease be 

 used when planting shade trees. 



Another quite destructive disease of shade trees in Maine 

 is the elm leaf -spot, caused by Gnomonia Ulinea (Sacc.) Thum.. 

 Shade trees are frequently badly defoliated by attacks of this 

 fungus and many complaints were received regarding such 

 instances during the past summer. Doubtless spraying would be 

 beneficial in the case of this disease as well as the horse- 

 chestnut leaf-spot. However it would doubtless be impractical 

 except where the matter of expense would be no consideration 

 or in those municipalities where special equipment has been 

 purchased to fight gipsy and brown-tail moths or other insect 

 pests. 



ORCHARD SPRAYING EXPERIMENTS IN I912. 



When Highmoor Farm came under the management of the 

 Maine Agricultural Experiment Station the pathologist planned 

 a series of experiments, particularly designed to test the efifect 

 of lime-sulphur and other sprays in controlling apple scab upon 

 those varieties of apples like the Ben Davis and Baldwin which 

 are quite susceptible to bordeaux injury. Bordeaux mixture 

 is a most effective agent in controlling apple scab but on the 

 varieties mentioned, and certain others, it frequently produces, 

 especially in wet seasons, much damage to both foliage and 

 fruit. So long as a horticulturist was stationed at the farm 

 during the summer months he could best conduct these experi- 

 ments, therefore they were transferred to his department. This 

 work has again come under the control of the pathological de- 

 partment. 



