Submitted to: Arkansas Agricultural Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: 6/30/2005
Publication Date: 9/30/2004
Citation: Kidd, J., Clark, J.R., Fenn, P., Smith, B.J. 2004. Evaluation of Post-harvest disease Resistance in Blackberry Genotypes. Arkansas Agricultural Experiment Station Research Series. p. 18-19. Interpretive Summary: Blackberry fruit rots annually cause extensive losses to blackberry farmers. The development of cultivars with increased resistance to fruit rot diseases should result in reduced use of fungicides and greater profits for growers. Fruit rot severity and incidence data were collected on 19 cultivars and 30 breeding selections genotypes developed at the University of Arkansas. Gray mold caused by Botrytis cinerea was the most common disease while ripe rot caused by Colletotrichum spp. occurred less frequently. Results indicated that resistance to these fruit rot diseases existed among the genotypes tested and that this resistance could be utilized in a breeding program to develop cultivars with higher levels of fruit rot resistance that is currently available. Among the cultivars tested, Kiowa and Triple Crown had the least amount of fruit rot. This information will be used by blackberry growers as they chose cultivars to plant and by blackberry breeders as they chose genotypes to use in their breeding program.
Technical Abstract: Forty-nine blackberry genotypes (19 cultivars and 30 breeding selections) were evaluated for post-harvest fruit-rot resistance in June and July 2003. Fully mature, undamaged berries were harvested on two dates for each genotype at the University of Arkansas Fruit Substation, Clarksville. After transporting in chilled coolers back to the Plant Pathology Department in Fayetteville, two replications of 10 berries of each genotype were placed in a high-humidity chamber for 3 d (21-23C; 16-h daylength). This provided a total of four replications for each entry across the two harvest dates. Natural inoculum from the field provided the post-harvest pathogens, and no additional inoculations were conducted. Berries were evaluated after 3 d in the chambers for the presence of postharvest rot. If rot was present, then a rating scale of 1 to 3 (1- very little mycelial growth present; 3=berry totally covered by mycelia) was used to quantify rot. The fungal growth was examined visually and microscopically to identify the causal pathogen. There was a wide range of post-harvest fruit-rot responses among the genotypes. The cultivars with the least rot were 'Kiowa', 'Triple Crown', and A-1689, with 80%, 73%, and 60% of berries free of any rots, respectively. Botrytis cinerea was identified on all berries that had any presence of rot and was the most important pathogen that contributed to berry decay. Colletotrichum spp. was found less frequently on rotted berries. Results indicate that substantial fruit-rot resistance existed among genotypes and variation for resistance could likely be used in breeding. Botrytis cinerea is the primary pathogen to target inpost-harvest fruit-rot breeding resistance at this study location.