Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 9, 2003
Publication Date: December 9, 2003
Citation: Polashock, J.J. 2003. Screening for resistance to botryosphaeria stem blight and phomopsis twig blight in blueberry.. Meeting Abstract. Paper No 4.
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 (Botryosphaeria dothidea) and Phomopsis twig blight (Phomopsis vaccinii). An attached stem assay was used for both pathogens in which the tips of selected branches were pruned off and the cut surface was inoculated with an agar plug containing the pathogen. Inoculated surfaces were covered with Parafilm and lesion lengths were recorded every two weeks. Final measurements were taken 4 weeks (B. dothidea) and 6 weeks (P. vaccinii) 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. The half-high (V. corymbosum x V. angustifolium) cultivars Chippewa and Northblue were the most resistant with the highbush cultivars Bluecrop, Brigitta Blue and Duke being the most susceptible. Phomopsis lesions ranged from about 18 mm to about 98 mm. Lowbush cultivars were the most resistant including 'Chignecto and 'Blomidon'. The most resistant highbush cultivars were 'Bluechip' and 'Rubel', both with an average lesion length of 26 mm. The most susceptible cultivars were the highbush 'Legacy' (67 mm) and the southern highbush 'Emerald' (98 mm). Those that were more resistant to one of the pathogens tested, were not necessarily resistant to the other, suggesting that different mechanisms may be associated with resistance to any given pathogen.