174 E-ErORT OF THE BOTAXIST OF THE 



Canker {Sphwropsis malorum Pk.) — Canker^ on the limbs and 

 trunks of apple trees is common throughout the whole district. 

 From the nature of the disease it is difficult: to determine 

 whether it has increased or decreased in virulence during 1900. 

 The fungus causing canker is also the cause of the black rot of 

 the fruit, and what appears to be the same fungus sometimes 

 attacks the leaves. We have searched carefully for it on both 

 fruit and leaves in many orchards where canker was abundant. 

 Occasionally we have found it attacking fruit still hanging on 

 the tree but the damage it does there is insignificant; its worst 

 effects are seen among stored fruit. We have failed to find the 

 fungus on apple leaves anywhere in Western New York.^*^ 



We have also sought for Cordley's^ apple-tree anthracnose 

 iungus, Gloeosporium malicorticis, but failed to find it. 



IIacrophoma Canker. — On May 10, we observed that the bark 

 ©n some cankered apple limbs in the Station orchard was thickly 

 covered with conspicuous creamy-white specks of pinhead size. 

 Upon microscopic examination these white specks proved to 

 be masses of the exuded spores of Maerophoma malorum (Berk.) 

 Berl. & Vogl. May 12 the same thing was observed in abundance 

 at Waterloo; May 16 at Dresden and Phelps; May 23 at Barker; 

 and May 24 at Hilton. It is plain that the exudation of 

 Slacrophoma spores on apple limbs during May was a common 

 occurrence. As a rule, the exudation was noticeably more 

 abundant on the side of the limb not exposed to the sun. At 

 Geneva the weather conditions preceding the exudation of spores 

 were as follows: For about a week prior to May 7 the weather 

 was cold and dry. During the night of May 7 there was a heavy 

 rain. May 8 was very warm and with a light rain at night. 

 May 9 was cloudy, damp and cold, becoming clear and colder at 

 night. 



'For a full discussion of apple-tree canker see Buls. 163 and 185 of this 

 Station. 



^'We have, however, collected it on apple leaves at Bayside, Lrong Island, 

 during the past season. 



"Cordley, A. B. Some Preliminary Notes on Apple-Tree Anthracnose. 

 Oreg. Agr. Exp. Sta., Bui. 60. 



