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ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Publications at this Location » Publication #361854
Research Project: Blueberry and Woody Ornamental Plant Improvement in the Southeast United States

Location: Southern Horticultural Research Unit

Title: Characterization and pathogenicity of stem blight complex isolates associated with stem blight disease on Vaccinium species

Author
item Babiker, Ebrahiem
item Stringer, Stephen
item Sakhanokho, Hamidou
item Smith, Barbara
item Polashock, James

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2019
Publication Date: 7/8/2019
Citation: Babiker, E.M., Stringer, S.J., Sakhanokho, H.F., Smith, B.J., Polashock, J.J. 2019. Characterization and pathogenicity of stem blight complex isolates associated with stem blight disease on Vaccinium species. HortScience. 54:1199-1203. https://doi.org/10.21273/HORTSCI14033-19.
DOI: https://doi.org/10.21273/HORTSCI14033-19

Interpretive Summary: Stem blight, caused by different species of Botryosphaeria and Neofusicoccum, is considered one of the most common diseases limiting the establishment of blueberry planting in southeastern USA. The temperature growth study revealed that the optimum temperature for growth of five of the tested isolates ranged from 25 to 30º C, although no significant difference was detected for the growth of isolate SD16-86 at 20, 25, 30, and 35º C. In vitro fungicide assays showed four fungicides, Switch, Pristine, Orbit, and Abound to be effective against tested isolates with isolate SD16-86 being less sensitive compared to the other isolates. In a detached stem assay, none of 39 tested blueberry accessions displayed immunity or a high level of resistance to two tested isolates, and no significant difference in lesion length was detected among the seven tested Vaccinium species inoculated with the two isolates. Further research is needed to test the efficacy of these fungicides in the field.

Technical Abstract: Species of Botryosphaeria and Neofusicoccum are major pathogens of blueberry worldwide. Accurate identification of these species is essential for developing effective management practices. A multigene sequencing strategy was used to distinguish between six isolates collected from two different regions of the USA. The temperature growth study revealed that the optimum temperature for growth of five of the tested isolates ranged from 25 to 30º C, although no significant difference was detected for the growth of isolate SD16-86 at 20, 25, 30, and 35º C. In vitro fungicide assays showed four fungicides, cyprodinil + fludioxonil, propiconazole, pyraclostrobin + boscalid, and azoxystrobin, to be effective against tested isolates with isolate SD16-86 being less sensitive compared to the other isolates. In a detached stem assay, none of 39 tested blueberry accessions displayed immunity or a high level of resistance to two tested isolates, and no significant difference in lesion length was detected among the seven tested Vaccinium species inoculated with the two isolates.