Location: Horticultural Crops Research UnitTitle: Weed management, training, and irrigation practices for organic production of trailing blackberry: I. Mature plant growth and fruit production
|DIXON, EMILY - Oregon State University|
|STRIK, BERNADINE - Oregon State University|
|VALENZUELA-ESTRADA, LUIS - Oregon State University|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2015
Publication Date: 9/1/2015
Citation: Dixon, E.K., Strik, B.C., Valenzuela-Estrada, L.R., Bryla, D.R. 2015. Weed management, training, and irrigation practices for organic production of trailing blackberry: I. Mature plant growth and fruit production. HortScience. 50(8):1165-1177.
Interpretive Summary: There is a growing body of research dedicated to blackberry growth and production, but there has been relatively little published on organic production of blackberries. The objective of the present study was to evaluate various production practices (cultivar, weed management, training time, and irrigation) for their effect on growth and organic production of mature trailing blackberry that were machine-harvested for the processed market. Withholding irrigation after harvest saved an estimated 650,000 gallons per acre over the 2 years of the study. Such reductions in irrigation after harvest in blackberry could result in considerable water and energy savings, as well as in environmental benefits. The impacts of weed management indicate that weed control is critically important for good blackberry production, and no weeding is a poor management option. Blackberry plants in the non-weeded treatment consistently produced fewer canes, less biomass, and a lower yield of lighter fruit than in either weed control treatment. In addition, plants grown with weed mat often produced more biomass and had a greater yield than those that were hand-weeded. Weed mat is, thus, an effective and economical method of weed control. Although August training has been shown to increase yield in ‘Marion’, this response was not observed in our study. August-trained plants produced the same yield as February-trained plants in 2013. In 2014, while training time did not affect yield in ‘Black Diamond’, there was more cold injury and less yield when ‘Marion’ was August-trained. August training appears to be risky in ‘Marion’ and is, thus, not recommended for organic production. Additionally, February training was an advantage in both cultivars for reduced weed pressure in the hand-weeded plots. Our study also showed that production systems that promote late-season growth such as weed mat and postharvest irrigation increased winter cold injury.
Technical Abstract: Weed management, training time, and irrigation practices were evaluated from 2013-2014 in a mature field of trailing blackberry (Rubus L. subgenus Rubus Watson) established in western Oregon. The field was planted in 2010 and certified organic in 2012, before the first harvest season. Treatments included two cultivars (‘Marion’ and ‘Black Diamond’), three weed management practices [non-weeded, hand-weeded or bare soil, and weed mat (black landscape fabric)], two irrigation strategies (irrigation throughout the growing season and no postharvest irrigation), and two primocane training dates (August and February). When averaged over the other treatments, ‘Marion’ and ‘Black Diamond’ had similar yields in both years. However, the presence of weeds reduced vegetative growth and yield, especially in ‘Black Diamond’, while weed mat increased growth and yield over hand-weeded plots by 13%. Withholding irrigation after harvest reduced water use by an average of 44% each year without adversely affecting yield in either cultivar. The effects of training time were primarily seen in 2014 after a cold winter. August-trained ‘Marion’ plants had more cold damage than February-trained plants and, consequently, had fewer and shorter canes, less biomass, fewer nodes, and 1 kg/plant less yield than February-trained plants. ‘Black Diamond’ was cold hardier than ‘Marion’, but was more readily infested by raspberry crown borer (Pennisetia marginata Harris). As the planting reached maturity, yields in the best performing organic production systems (both cultivars under weed mat and ‘Marion’ that was February-trained) averaged 11 and 9 t/ha, for ‘Black Diamond’ and ‘Marion’ respectively, similar to what would be expected in conventional production.