Volume 53 Number 1 Article 7
Year 1999 Month 1
Title: Susceptibility of Southern Blueberry Cultivars to Botrytis Blossom Blight
Author: B.J. Smith
Abstract:
The susceptibility of blueberry flowers at various developmental stages was evaluated by inoculating potted blueberry bushes of the rabbiteye cultivars, 'Climax', 'Premier' and 'Tifblue', and the southern
highbush cultivars, Magnolia and Jubilee, during bloom with a conidial suspension of Botrytis cinerea.
Inoculated plants were then incubated in a dew chamber for two days at 20°C and 100% RH. Flower
stage was rated at the beginning of the study and two weeks after inoculation. Botrytis disease symptoms were scored two weeks after inoculation on a visual scale of 0 to 7. Susceptibility to Botrytis
blossom blight was greatest on more developed flowers.
Buds inoculated at stage 2 through stage 3
(prebloom) developed few disease symptoms, while flowers inoculated at stages 5 to 7 (full bloom) developed more severe symptoms. 'Magnolia,' 'Premier,' and 'Tifblue' flowers at stage 6 were very susceptible.
When averaged over the more susceptible flower stages (5, 6 and 7), 'Jubilee' and 'Premier'
had the lowest disease severity scores. 'Tifblue' had higher disease scores than 'Magnolia' and 'Climax.' The two southern highbush cultivars did not differ as a group from the three rabbiteye cultivars
in their susceptibility to Botrytis blossom blight.
Since susceptibility of blueberry flowers is greatest
at or near full bloom, fungicide applications for Botrytis blight control of southern blueberries should
begin at flower stage 4 and continue though stage 6.
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