Submitted to: Small Fruit Reviews
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2003
Publication Date: 7/28/2004
Citation: Smith, B.J. 2004. Susceptibility of southern highbush blueberry cultivars to botryosphaeria stem bight. Small Fruit Reviews. Vol.3, No. 1/2, 2004, pp. 193-201. Interpretive Summary: A laboratory assay was used to determine the susceptibility of 20 southern highbush blueberry cultivars to stem blight which is a destructive disease of blueberries in the southeastern U.S. There are no fungicides available for control of this disease; therefore, resistant cultivars and cultural practices offer the most promise for its control. Little is known of the susceptibility of new southern highbush blueberry cultivars to stem blight. Ten southern highbush, one rabbiteye, and two low chill highbush cultivars were identified as resistant. The results of this study are important to southern blueberry growers as they choose which cultivar to plant and to blueberry breeders as they choose parents to use in their breeding programs.
Technical Abstract: Stem blight, caused by the fungus Botryosphaeria dothidea, is a destructive disease of rabbiteye and highbush blueberries in the southeastern United States. Southern highbush blueberry cultivars, hybrids between V. corymbosum and various native "southern" blueberry species, increasingly are being released for production in the coastal plains of the southeastern U. S. because they have a low winter chill requirement, bloom late, and fruit early in the growing season. Little is known about their susceptibility to stem blight and other diseases. As acreage of southern highbush blueberry cultivars increases, so does the potential threat of losses due to stem blight and other diseases. The susceptibility of 20 southern highbush cultivars (Biloxi, Bluecrisp, Cooper, Emerald, Georgiagem, Gulf Coast, Jubilee, Legacy, Magnolia, Misty, O'Neal, Ozarkblue, Pearl River, Reveille, Santa Fe, Sapphire, Sharpblue, Southmoon, Star, Windsor), two rabbiteye cultivars (Tifblue and Brightwell), and two highbush cultivars (Darrow and Elliott) were compared using a detached stem assay. Two fresh isolates of B. dothidea obtained from infected southern highbush blueberry plants grown at Poplarville, MS were used as inoculum in this study. Succulent, partially-hardened stems with three intact terminal leaves were surface disinfected, rinsed in sterile distilled water, wounded by scraping away a section of bark, and inoculated by covering the wound with 2 mm mycelial agar block of B. dothedia with parafilm wrap. The base of each stem was inserted into moistened, sterilized sand in a 150 x 25 mm tissue culture tube and incubated at 25 C, 100 % RH for 30 days. Cultivar susceptibility was determined by measuring lesion length at 15 and 30 days incubation. Cultivars whose average lesion length at 15 days was no different than that of the non-inoculated control treatment were rated resistant and included Pearl River, Emerald, Star, Sharpblue, Elliott, Misty, Bluecrisp, Darrow, Southmoon, Ozarkblue, Sapphire, and Brightwell.