1911.] PUBLIC DOCUMENT — No. 31. 171 



Avliereas. it' the troiil)Ic had been due to a fungus, tbo iicw leaves 

 Avuuld also become affected. Bordeaux is not, therefore, always 

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

 has often been known to cause trouble when used at only half 

 strength. 



GUMMOSIS OF THE PeACK. 



For the past two years there has been an abundance of gum 

 flow in the college peach 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 seemeil best to destroy 

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

 scribe resembles almost identically in most of its life history the 

 gummosis of Frunus Japonica, described by Massee as due to 

 Cladosporhim epipJiylhiin, Fr. In this ease (gummosis of 

 peach) I believe the species to be Cladosporhim, cai-pophylum, 

 Thiim. Massee mentions in his paper a species of Macrospo- 

 riuni 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 Macrosporium fungus in connec- 

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

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

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

 ordinary alternaria spores, bears pycnidia bodies containing 

 many minute byline spores. These in turn give rise to Alter- 

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

 lish any genetic connection between this form of Alternaria. 

 and the Cladosporium. 



Prohahle Cavse of Gummosis. 

 On the trunks and large branches the gum flow is evidently 

 due to borers, 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 Alterunria, 

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

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

 these forms of Cladosporium and Alternaria take a hand in 



' The organism which we term Alternaria here may possibly bean undeveloped form of some 

 other type, such as Pleospora, etc. 



