ARS | Publication request: Comparison of visual and electronic evaluations of detached strawberry leaves inoculated with colletotrichum species

Submitted to: International Journal of Fruit Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2011
Publication Date: October 3, 2012
Citation: Miller Butler, M.A., Curry, K.J., Kreiser, B.R., Smith, B.J. 2012. Comparison of visual and electronic evaluations of detached strawberry leaves inoculated with colletotrichum species. International Journal of Fruit Science. 13:114-125.

Interpretive Summary: Strawberry breeding programs generally require many years to produce disease resistant cultivars. Detached leaf inoculation techniques allow researchers to test strawberry germplasm for disease susceptibility without destroying whole plants, reduce the time between inoculation and disease assessment, and protect the environment since the pathogen is confined to the laboratory. The objective of this study was to compare computer based image alaysis of anthracnose disease on inoculated detached strawberry leaves with visual disease assessments and to determine how well the visual assessments correlated to the computer assessment. Another goal was to determine if the detached leaf technique reliably distinguished anthracnose resistant germplasm from susceptible germplasm. There was a strong positive correlation between the computer based image analysis and the visual assessments which suggests that visual disease scores are sufficiently reliable and reproducible to determine disease response in inoculated plant material. Our research results will be valuable to strawberry breeders because it enhances their ablility to identify strawberry germplasm resistant to anthracnose disease in less time than traditional methods. Plant pathologists will find this information useful when implementing inoculation studies.

Technical Abstract: Inoculation of detached strawberry leaves with Colletotrichum species may provide an accurate, rapid, non-destructive method of identifying anthracnose resistant germplasm. Two measures of anthracnose disease severity were compared on detached strawberry leaves inoculated with Colletotrichum fragariae and C. gloeosporioides: a quantitative assessment made via computer based image analysis and a visual assessment made by two independent raters. The image analysis provided a precise measurement of percent lesion area of infected leaves. There was a strong positive correlation between percent lesion area and the visual disease scores of the raters.