CALIFORNIA AVOCADO ASSOCIATION 



13 



erwise, it causes the well-known dead spots, on the surface of which 

 may be seen the minute black fruiting bodies of the fungus. This 

 leaf trouble of the avocado is undoubtedly primarily due to physio- 

 logical rather than pathological causes. By remedying unfavorable 

 soil or moisture conditions and promoting a vigorous growth of 

 the trees it would seem that this weakness can be more or less 

 overcome. 



Some specimens of the Chappelow avocado received in Septem- 

 ber, 1915, were thoroughly ripe, and two showed signs of a peculiar 

 softening evidently due to the action of some fungus. The fruit 

 was therefore submitted to Prof. Horne of the Division of Pathol- 

 ogy, Berkeley, Avho later submitted this report, which I wish to 

 include with my paper: 



REPORT ON FUNGUS ROT 



"On the first two fruits brought to me on September 21st it 

 was very evident that several types of decay were active and several 

 organisms present. The most frequent type of decay consisted of 

 small, slightly sunken spots, which looked as though there had been 

 simply a dent made by rather small fingertips, and some white fun- 

 gus was growing in the hollow. These spots were of rather frequent 

 occurrence, scattered over both of the fruits submitted. I have not 

 yet been able to determine in a way satisfactory to myself whether 

 this type of rot is due in all cases to the same organism, or whether 

 several kinds of fungi may cause the same kind of injury. The 

 fungi growing in these spots and on the surface of the fruit seem 

 to be rather numerous and varied. I have cultivated a Fusarium 

 of a rather peculiar type, an Alternaria, which, so far as I can tell 

 up to the present time, might be identical with the fungus causing 

 black heart of oranges, and a small fungus producing very definite 

 fruiting bodies in which no spores have yet formed, which might 

 be some form of Phoma. There were also developed on the fruits 

 which were kept in a moist dish, some Penicilliums, Cladosporium, 

 Acremonium or Sporotrichum, and some other fungi not certainly 

 recognized. It will be seen that the number of fungus forms Avhich 

 appear on overripe avocados are very numerous. 



"In addition to tlie fungi Avhich developed on the fruits in moist 

 chamber, bacteria of several kinds also developed. The form of 

 1)acteria which has come to predominate in these spots is one which 

 forms a copious sticky brown mass, and when it becomes slightly 

 dry, a wrinkled pellicle on the surface. The odor is offensive but 

 not exceedingly strong, nor is it like the odors given off by putrify- 

 ing meat or vegetables, such as cabbage and turnips. 



"From examination of the decaying fruits it appears that neither 



