8 BULLETIN 924, U. S. DEPARTMENT OF AGRICULTURE. 



Tasle IV. — Isolation of Colletotrichum gloeosporioides, Cladosporium sp., and miscel- 

 laneous organisms from orange and grapefruit rind affected with melanose or with 

 'shark skin." 





Variet y. 



Remarks. 



Series A , diffused 

 patches. 



Series B, tear- 

 streak pattern. 



Series C, un- 

 blemished. 



Lot and num- 

 ber of fruits 

 in group. 



5 8 



li 



So 

 o ft 



c O 

 ^ 03 



o = 



Cladosporium. 



o 



o 



a 



03 

 O 



11 



° a 



S o 

 3 o 

 o o 



S 

 c 

 o 



o 



o 

 o 



a 

 .9 



1 



a 



£ 3 



o ft 

 c o 

 S a> 



o o 



| 



o 



o 



■a 

 — 



G 



5 



o 



N ot d i s i n- 

 fected: 

 Lot E, 4 



Grapefruit. 

 do 



Melanose t car streaks 



Bright area on mela- 

 nose fruits. 

 Melanose tear streaks 







40 



41 51 









fruits. 

 Do... 









27 



12 



23 

 5 



40 



Lot G, 2 



do 



do 



do 



Orange 



Grapefruit . 



do 



do 









8 

 5 



11 

 2 



45 

 1 



15 



fruits. 

 Lot L, 2 











fruits. 



Lot N, 1 



Mud-caked melanose . 

 Decided ' ' shark skin " 

 do 



32 

 31 ■ 

 25 



19 



17 

 15 



C7 

 49 

 11 









fruit. 

 Lot J, 4 















fruits. 

 Lot K, 4 















fruits. 

 Disinfected: 

 Lot E, 4 



Melanose tear streaks . 



Bright area on mela- 

 nose fruits. 

 Melanose tear streaks . 



...do 



5 



1 



.3 









fruit a, 

 Do... 









6.5 



.5 



2 



.3 



Lot G, 2 



do 



do 



do 



Orange 



Grapefruit ' 









36 

 5 



- 



1 



2 



fruits. 

 Lot L, 2 











fruits. 

 Lot N, 1 



Mud-caked melanose . 

 Decided "shark skin " 

 do 



S. 5 

 G 

 19 



2 



1 



1 



1 



3.5 









fruit. 

 Lot J, 4 















fruits. 

 Lot K, 4 















fruits. 













It appears from Table IV that ■: olletotrichum gloeosporioides is 

 recovered with about the same frequency as is shown in Table III, 

 thus indicating that no positive conclusion as to the causation of 

 tear-stain can be reasonably based on isolation tests. 



All the cultural work shows that Colletotrichum gloeosporioides 

 has an isolation percentage from tear-stained areas rather too low 

 for it to be the active pathogen and that this organism is present 

 to some extent on normal as well as badly russeted areas, the fre- 

 quency varying with the degree of injury. 



The fungi in various types of miscellaneous lesions on citrus fruits 

 were examined by similar cultural methods. These lesions included 

 spray-burn scars, hail bruises, thorn scratches, and old citrus-scab 

 lesions. The fungous flora was very similar to that obtained from 

 tear-stained and russeted areas. Colonies of Colletotrichum pre- 

 dominated, the saprophytic Cladosporium ranked next, while col- 

 onies of bacteria and various other fungi occurred in smaller numbers. 



