ARS | Publication request: SCREENING FOR RESISTANCE TO BOTRYOSPHAERIA STEM BLIGHT AND PHOMOPSIS TWIG BLIGHT IN BLUEBERRY.

Submitted to: Acta Horticulturae International Symposium on Vaccinium Culture
Publication Type: Proceedings
Publication Acceptance Date: February 27, 2005
Publication Date: February 27, 2005
Citation: Polashock, J.J. 2004. Screening for resistance to botryosphaeria stem blight and phomopsis twig blight in blueberry.. Acta Horticulturae International Symposium on Vaccinium Culture.

Interpretive Summary: Stem diseases of blueberry can cause significant crop loss as well as loss of entire bushes. Stem diseases are also difficult to manage with currently available chemical controls. To reduce dependence on chemical control, we have initiated a program to screen blueberry cultivars for resistance to two important stem diseases namely Botryosphaeria stem blight and Phomopsis twig blight. An attached stem assay was used to screen for resistance to both pathogens. Resistance was measured by comparison of stem lesion lengths after inoculation, with those developing smaller lesions being more resistant. Final measurements were taken at 4 weeks (stem blight) and 6 weeks (twig blight) after inoculation. Whole potted plants representing 52 cultivars were used for the study. For stem blight, lesions varied from about 10 mm in resistant cultivars to around 140 mm in susceptible varieties. Phomopsis twig blight lesions ranged from about 18 mm to about 98 mm. Those cultivars that were resistant to one disease were not necessarily resistant to the other. Resistance to these two diseases is available in the current cultivar collection and thus, will be of use to blueberry breeders interested in developing superior cultivars.

Technical Abstract: Stem diseases of blueberry can cause significant crop loss as well as loss of entire bushes. Stem diseases also tend to be more difficult to control with fungicides than foliar or fruit diseases. We have initiated a program to screen blueberry cultivars for resistance to two important stem diseases namely Botryosphaeria stem blight and Phomopsis twig blight. An attached stem assay was used to screen for resistance/susceptibility to both pathogens. Resistance/susceptibility was measured by comparison of stem lesion lengths after inoculation. Final measurements were taken at 4 weeks (stem blight) and 6 weeks (twig blight). Whole potted plants representing 52 cultivars were used for the study. For stem blight, lesions varied from about 10 mm in resistant cultivars to around 140 mm in susceptible varieties. Phomopsis twig blight lesions ranged from about 18 mm to about 98 mm. Those cultivars that were resistant to one pathogen, were not necessarily resistant to the other.