STUDIES OP GLOMEEELLA FROM DIFFERENT HOSTS. 



21 



showed no signs of the fungus. Segment No. 2 showed no indication 

 of the fungus on either leaf or stem; No. 3 showed a slight uniform 

 discoloration of leaf only; No. 4 showed discoloration of the leaf along 

 the midrib and a very few acervuli. Three young fruits on this por- 

 tion were also discolored and acervuli abundant on the calyx of one; 

 also on the leaf petiole. No. 5 showed discoloration of the basal 

 "portion of the leaf and of the stem only. Nos. 6 and 7 showed leaf 

 and stem almost entirely discolored, but no acer- 

 vuli. In No. 8 the basal portion of the leaf was 

 discolored and a slight discoloration appeared on 

 one side of the leaf, but no acervuli were present. 

 No. 9 showed acervuli on the stem, but the leaf 

 was not discolored. No. 10 had the entire leaf dis- 

 colored. No. 11 showed the leaf almost wholly 

 discolored, with the fruit black and bearing acer- 

 vuli. On No. 12 the leaf and stem were almost 

 entirely discolored, with acervuli at the base of 

 the leaf. No. 13 showed the fruit completely dis- 

 colored and acervuli present, but the leaf was not 

 discolored. No. 14 showed the leaf entirely dis- 

 colored, with acervuli on the cut surfaces of the 

 stem. In No. 15 the leaf was almost entirely dis- 

 colored, but no acervuli were present. 



On May 20 leaves on Nos. 2 and 9 were still 

 a normal color; all others,' except 11 and 13, 

 which were entirely discolored, showed abundant 

 acervuli. Acervuli were present on all the fruits. 

 On May 25 Nos. 2 and 9 had become discolored and 

 showed abundant acervuli. Acervuli were also 

 abundant on Nos. 11 and 13.* 



As a result of this experiment it will be noted 

 that the fungus was present in all the leaves of the 

 new growth as well as on the growth of the previ- 

 ous year. The fungus developed more rapidly on 

 the older leaves. The early and vigorous develop- 

 ment of the fungus in the young fruits and the 

 leaves situated at their bases and the rather tardy 

 development of the fungus in leaves remote from 

 the blossoming shoots — that is, Nos. 2 and 9 — seems to indicate a 

 downward course of development of the fungus and infection by 

 way of the blossoms, as shown by Rolfs (66) and Bessey (12). 



Fig. 1.— An apparently 

 healthy fruiting branch 

 of an orange taken from 

 a greenhouse plant, di- 

 vided into 15 parts as 

 indicated, then washed 

 thoroughly in corrosive- 

 sublimate solution and 

 kept in sterile moist 

 chambers. Glomerella 

 cingulata developed on 

 all the leaves and fruit 

 in such a manner as to 

 indicate a probable ori- 

 gin from infection of the 

 blossoms. 



CULTURES. 



Numerous cultures have been made from conidia and ascospores 

 obtained from orange leaves. Apparently healthy, vigorous orange 



252 



