146 HATCH EXPERIMENT STATION. [Jan. 



Oak Leaf Blight {Gloeosporium nervisequum, (FcM.), 



Sacc). 



A fungus apparently identical with that which causes the 

 blight of the sycamore is sometimes found upon the white 

 oak. This produces large dead blotches upon affected leaves, 

 and causes great disfiguration of white oak trees. 



Walnut Leaf Blight (Gloeosporium Juglandis, (Lib.), 



Mont.). 



This disease was mentioned in our last report as having 

 been especially abundant during 18.97. It has also occurred 

 this year, but to a much less extent. 



These diseases are briefly mentioned because complaint 

 has been frequent during the past summer in regard to them, 

 largely, however, from people who possess shade trees which 

 they value. From what we know in regard to the treatment 

 of similar fungi occurring on other plants, it would seem 

 that spraying might hold some of these in check ; and the 

 only reply which can be made is, Are the trees valuable 

 enough to receive treatment? Some of these fungi attack 

 large groves, and the expense of spraying would amount to 

 considerable. As a rule, these fungi only make their ap- 

 pearance at intervals, and do not injure the trees to any 

 great extent. In consideration of this fact, it appears ques- 

 tionable to us whether they are worth the trouble ; but, 

 should spraying be deemed necessary, it would have to be 

 done early and continued each year. 



The disease of the peach known as the ' ' leaf curl " 

 (Exoascus deformans, Fckl.) has been unusually abundant 

 during the past season. This disease is well known to most 

 peach growers, causing the leaves to become wrinkled and 

 curled and greatly deformed, finally resulting in their falling 

 to the ground. It is not ordinarily regarded as an especially 

 destructive disease, and does not often cause any appreciable 

 damage to the tree ; but, when so abundant as to cause a 

 large proportion of the leaves to fall, it cannot but injure 

 the tree to some extent. 



