UNITED STATES DEPARTMENT OF AGRICULTURE 



j&rs&jt. 



BULLETIN No. 924 <* 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



January 26, 1921 



TEAR-STAIN OF CITRUS FRUITS. 



By Johx R. Winston, 

 Pathologist, Office of Fruit-Disease In instigations. 



CONTENTS. 



Page. 



Description of the disease 1 



Review of the literature 2 



Spraying experiments 3 



Cultural work 5 



Histological examination 9 



Tage. 



Inoculation experiments 9 



Conclusions 11 



Summary II 



Literature cited 12 



DESCRIPTION OF THE DISEASE. 



Florida citrus fruits are subject to two distinct types of tear- 

 streaking, namely, wither-tip tear-stain and melanose tear-streak. 

 Trie former has been attributed to Colletotrichum gloeosporioides 

 Penz., while the latter, which will not be discussed in this bulletin, 

 is doubtless due to a peculiar distribution of the spores of the: 

 causal organism (PTiomopsis citri Fawcett) in trickling waters. 



Wither-tip tear-stain is a smooth, more or less brownish discolora- 

 tion of the surface which occurs typically in fingerlike patterns^ 

 about one-fourth of an inch in width, extending longitudinally 

 toward the stylar or blossom end of the fruit. (PL I.) These 

 streaks may or may not be confined to one side of the fruit, and 

 frequently they appear to arise in areas russeted by rust mites 

 (Eriophyes oleiveros Ashmead). The streaks are usually few in 

 number, seldom more than six or eight: occasionally two or more 

 merge and form a rather wide discoloration, in which event the 

 injury is generally attributed to rust mites. (PI. II, fig. 1.) 



Wither-tip tear-stain as it occurs in Florida is one of the minor 

 diseases of citrus fruits, and for that reason it has received little 

 attention from investigators. Its effects are principally observed 

 on the round orange and grapefruit, more noticeably and frequently 

 on the latter and to a less extent upon other economic species of 

 citrus. 



15580°— 21— Bull. 924 



