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STUDIES IN THE BACTERIAL DISEASES OF SUDAN CROPS
Author(s) -
SABET K. A.
Publication year - 1960
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1960.tb03556.x
Subject(s) - biology , inoculation , germination , apex (geometry) , botany , leaf spot , host (biology) , horticulture , ecology
The atypical symptoms first described by Bryan (1932) of the angular leaf spot disease of cotton caused by Xanthomonas malvacearum (E. F. Sm.) Dowson were reproduced by inoculation into seeds, stem apices or buds. The lesions that developed on the veins of the newly produced leaves were elongated and water‐soaked, becoming dark brown. The leaf tissue dependent upon infected veins became yellow, flaccid and withered. The development of these symptoms was enhanced when inoculations were made into opening buds or germinating seeds as compared with inoculations into closed buds or dormant seeds. In other bacterial diseases caused by Xanthomonas spp., somewhat atypical symptoms could also be produced by bud inoculation into the appropriate host. Those produced by X. ricini (Yoshi & Takimato) Dowson on castor, closely resembled the vein lesions described above on cotton but resulted only from bud inoculations; inoculations into stem apices and seeds failed to produce them. In dolichos bean inoculated with X. phaseoli (Smith) Dowson, atypical symptoms were produced only by seed inoculations and were confined to the first simple leaves (prophylls). The differences in the production of atypical symptoms on the three hosts are correlated with differences in host structure and with the degree of virulence of the pathogen. The leaf parasite X. ricini , for example, which cannot infect castor bean stems, does not produce atypical symptoms when inoculated below the stem apex. From the data discussed below, the incidence of atypical symptoms is attributed to infection either of an actively growing tissue or of a telescoped structure which subsequently completes its development. The atypical symptoms of the cotton disease are not caused by a special strain of X. malvacearum. Further, they are not a peculiarity of this disease but may also develop in other necrotic diseases under similar conditions.