Location: Southern Horticultural ResearchTitle: White Drupelet Disorder on Three Blackberry Cultivars in South Mississippi
|STAFNE, ERIC - Mississippi State University|
|REZAZADEH, AMIR - Mississippi State University|
|MILLER-BUTLER, MELINDA - Former ARS Employee|
Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2017
Publication Date: 12/31/2017
Citation: Stafne, E.T., Rezazadeh, A., Miller-Butler, M., Smith, B.J. 2017. White Drupelet Disorder on Three Blackberry Cultivars in South Mississippi. HortTechnology. 27:840-84.
Interpretive Summary: White drupelet disorder (WDD) in blackberries is a tan-to-white discoloration of one to many drupelets on the fruit. WDD is thought to be a genetic disorder that is affected by environment; however, we did not see was any interaction of cultivar and environment, i.e., all three cultivars responded the same way to the environmental changes to which they were subjected. We may be able to infer that any condition that reduces WDD in one cultivar would also do so in another (at least for these three cultivars). Based on our results, we can conclude (1) rain decreases symptoms of WDD, therefore, overhead irrigation may have a similar effect; (2) 30% shade decreases symptoms of WDD, and perhaps a higher % would further decrease WDD; (3) sugar levels were also decreased under shade; and (4) All cultivars responded in a similar manner to the weather conditions. Both ‘Chickasaw’ and ‘Kiowa’ had low levels of WDD in both years, whereas ‘Sweetie Pie’ had 22% in 2016 when temperatures were higher and rainfall was less, but that fell to 13% in 2017.
Technical Abstract: White drupelet disorder (WDD) is a problem that occurs during the ripening stage in some blackberry cultivars. Although berries affected with a few white drupelets may taste fine, they are unpleasant aesthetically; and this may lead to negative economic ramifications. During two years of experiments (2016 and 2017), we evaluated changes in three susceptible cultivars in Mississippi affected by WDD. ‘Chickasaw’, ‘Kiowa’, and ‘Sweetie Pie’ berries were harvested twice per week and assessed for WDD. Weather conditions differed substantially during harvest in 2016 and 2017, with 2017 being cooler and rainier which resulted in a lower incidence of WDD. Compared to 2016, in 2017 the overall percentage of berries exhibiting WDD dropped from 22% to 12% for ‘Sweetie Pie’, 6 % to 3% for ‘Chickasaw’, and 8% to 3% for ‘Kiowa’. The sugar content was highest in ‘Sweetie Pie’, 11.86 and 9.47 % soluble solids for 2016 and 2017, respectively. The soluble solids concentration of extracted white drupelets was substantially lower than regular drupelets. The value for skin break force for white drupelets was higher than that for black drupelets, 0.99 N versus 0.29 N, respectively. In 2017, a ˜ 30% shade cloth treatment had a significantly positive impact by decreasing WDD symptoms in all cultivars by 63% when compared with non-shaded plants, but sugar content was lower. Our results indicate that rain and shade cloth decrease symptoms of WDD. Therefore, growers may be able to use overhead irrigation and shade to reduce WDD symptoms.