Submitted to: Mississippi Academy of Sciences Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2001
Publication Date: N/A
Technical Abstract: The mechanism C. rubi uses to obtain nutrients from blackberry may be both saprophytic and parasitic. Cercosporella rubi is present from the time floral differentiation is initiated until mature flowers become senescent. Throughout floral development, hyphae are dense in crevices among carpels, stamens, petals, and sepals. Host cells appear healthy although hyphae, sheathed by a matrix, are closely appressed to the epidermis. Uninjured host cells would be expected since penetration structures have not been observed. Cercosporella rubi might absorb plant exudates from the surface of floral organs. Accumulation of exudates within crevices would provide an explanation of why more hyphae are found in crevices. In addition, C. rubi might take advantage of moribund tissue. Two ovules are produced during ovary development. One ovule naturally aborts at some point during development. Hyphae are found surrounding the deteriorating ovule and within collapsed tissue. These observations suggest that C. rubi express a saprophytic phase. Healthy carpels appear further along in development than infected carpels on floral buds of the same diameter. This may be due to hyphae interfacing with suture closure during carpel development. Cercosporella rubi might be accelerating senescence by curtailing floral development. These observations suggest that C. rubi is expressing both parasitic and pathogenic phases.