1911.] PUBLIC DOCUMENT — No. 31. 171 



Avhcrciis. if the troiihle had been due to a finigus, the new leaves 

 Avouhl also become aiVected. Bordeaux is not, therefore, always 

 safe to use on mature foliage, even at reduced strengths, for it 

 has often been known to cause troul)le when used at only half 

 strength. 



GUMMOSIS OF TlIK PkACTI, 



For the past two years there has l)e(»n an al)undance of gnm 

 fl<»w in the college jieach orchard. This has been found to the 

 greatest extent on the early varieties, and owing to the poor 

 condition of many of the trees it has seemed best to destroy 

 them. The following gum disease which I am about to de- 

 scribe resembles almost identically in most of its life history the 

 ginnmosis of Primus Japunica, described by Massee as due to 

 ('ladosporhim epiphyllum, Fr. In this ease (gummosis of 

 ]ieaeh) I believe the species to be Cladoaporium carpophylum, 

 Thiim. ^Massee mentions in his paper a s])ecies of Macrospo- 

 rium that is often found in connection with this gum flow, but 

 he is unable to find any genetic connection between the two 

 fungi. Instead of finding a Macrosporivni fungus in connec- 

 tion with the gunnnosis of peach, I have, with very few excep- 

 tions, found a species of Altemaria ^ or AUernaria form, which 

 is apparently something new, as the fungus, in addition to the 

 ordinary alternaria spores, bears pycnidia bodies containing 

 nuiny minute byline spores. These in turn give rise to AUer- 

 naria spores and more pycnidia. I could not, however, estab- 

 lish any genetic connection l)etween this form of Alternaria 

 and the Cladosporiuin. 



Prohahle Cause of Gummosis. 

 On the trunks and large branches the gum flow is evidently 

 due to l)orers, frost cracks and sun scald, and a copious flow of 

 gum at any place of injury is generally found. These places 

 serve as a refuge for the spores of Cladosporium and Alternaria , 

 and we find some form of Penicillirtm inhabiting the same mass. 

 But whatever the original cause of the flow, it is certain that 

 these forms of CJadosporiiim and Alternaria take a hand in 



' The organism which we term AUernaria here may possibly he an undeveloped form of some 

 other type, such as Pleospora, etc. 



