DISEASES DUE TO ISACTERIA, FUNGI AND OTHER LOWER PLANTS IIQJ 



During their phase of maximum growth, those varieties of Citrus which 

 are most subject to the disease emit a strong aroma suggestive of acid. Under 

 normal conditions it is volatiHsed, but when the leaf is covered with a thin 

 la^'er of water, it enters into solution and is concentrated to such an extent 

 as to attack the most superficial tissue. 



Furthermore, the presence of water on the leaves ]jromotes the growth 

 of the glands. When the latter grow to an excessive extent, their walls are 

 thinned and thej^ often break, the contents being emptied on to the leaves 

 and the rind of the fruit. The edges of these glands afterwards grow to 

 such an extent as to form a crater-shaped hollow, in which the remains 

 of the epidermal cells are found. When on the other hand the growth of 

 the leaf in area predominates, the original injury due to breaking of the 

 gland extendS; and exhibits the characteristics of the disease. 



The writer has been unable to establish definitely the chemical composi- 

 tion of the glandular content of C. decnmana var. PomeZo. Nevertheless, it 

 is known that the main constituents of orange oil, such as limonene, an- 

 thranilic acid and anthranilate of methyl, when applied to the leaves or 

 fruits by means of a sprayer cause serious injuries. 



The excessive growth of the oil glands, the injuries due to their burst- 

 ing, the emergence and accumulation of their contents on the leaves and on 

 the fruits, all of them phenomena which are facilitated by wet weather and 

 cold, appear to be clearly connected with the origin and development of 

 the disease. 



The opinion obtaining hitherto, acording to which Cladosporium Citri 

 was the specific pathogenic agent, cannot hold good in view of the negative 

 results obtained by the writer during a lengthy series of experiments. On 

 small plants disinfected with bichloride of mercury at a strength of i " Vio and 

 growing under conditions precluding all possible infection, the disease deve- 

 loped, and on the other hand it was not found possible in any ca.se to cause 

 it by inoculating spores of Clodosporium into the tissues of healthy plants. 



Various experiments in connection with the application of remedies were 

 carried out in two localities : at Orlando and Bradentown. The results 

 are summarised up in the appended table. 



It is advised to apply Bordeaux mixture at tliL- height of the flowering 

 period, following it, after an interval of 8 or lo days, with an application of 

 lime - sulphur solution and, three weeks later, with a second treatment, again 

 with lime sulphur solution. 



DISEASES DUE TO FUNGI, BACTERIA 

 AND OTHER LOWER PLANTS. 



■i2<, ~ Contributions to the Study of the Mycology of Liguria, Italy. — maiiki Ltioi in 



Atti del R. Istituto botanico dclF I'nivcrsitd di Pavia. Ilnd Scries, VoL XVI, pp. :;25-::.i3. 

 PL XVII. Milan, 191 6. 



In this fourth contribution to the study of Ligurian mycology, the writ- 

 er gives a systematic list of 141 species of fungi of which 85 are recorded 

 for the first time in Liguria. 



GEXER.'\LITmS, 



