Update - Growing Blackberry Production and Sales in Missouri project

Published: June 14, 2019

Blackberries are a viable commercial fruit crop for farmers in Missouri and other states in the Midwestern region of the United States. Recent advances in blackberry cultivar development and production practices have greatly enhanced the profit potential of this crop for farmers, and several markets (on farm sales, farmers markets, wholesale markets, and institutional markets) are clamoring for locally grown blackberries.

A blackberry planting was established at the University of Missouri Southwest Research Center (SWRC) in Mount Vernon, Missouri, USA in March 2016. Funding for the project was provided by a MDA Specialty Crop Block Grant. The planting highlights recent blackberry cultivar and production technology developments and is a powerful demonstration site for adult learning. The planting features:

• Seven thornless blackberry cultivars ('Natchez', 'Osage', 'Ouachita', 'Apache', 'Triple Crown', 'Prime-Ark® Freedom', 'Prime-Ark® Traveler') planted in 2016 in a completely randomized design, with three replications of each cultivar and three plants per replication. We collected data on fruit yield, fruit size, and ripening time in 2017 and 2018; the data highlight the potential of these cultivars for profitable production in Missouri.
• The rotating cross arm (RCA) trellis, an innovative trellis design that allows farmers to change the orientation of the blackberry plant and overcome several factors that that limit blackberry profitability in Missouri. The trellis design allows farmers to concentrate the berry crop on the shady side of a supported canopy that effectively divides the floricanes from the primocanes. The trellis allows farmers to protect plants from winter conditions with rowcovers, reduce fruit loss from sunscald, and improve pest management and harvest efficiency. Details on the design and use of the RCA trellis are found at https://web.extension.illinois.edu/mms/downloads/47252.pdf

  RCA trellis, showing the winter/spring position (left) and the summer/fall fruiting position.

• Innovative production practices, including the use of tissue culture plug plants, raised beds, drip irrigation, spotted wing drosophila (SWD) trapping, weed barrier fabric mulch for weed control, and floating row cover for winter protection.

The planting consists of 3 rows that are 12 feet apart, oriented east to west. Plants are planted 5 feet apart in plots of 3 plants per cultivar, with 3 plots per cultivar in the planting. The plants are on raised beds that are 36" wide and 8" high. We covered the beds with woven landscape fabric, and placed a single 18mm dripline per row, with 18" emitter spacing. We followed standard cultural practices with regard to preplant soil testing and soil modification, planting establishment, pest management, and weed management between rows (which were in sod). The planting was fertigated weekly from April to September, for an equivalent of 80 total lbs/acre of nitrogen per growing season.

The RCA trellis system offers huge benefits as described above, but we learned that timely management is critical to see these benefits. We carried out the following practices:

• Mid March: remove the floating row covers; apply delayed dormant lime sulfur fungicide, raise and then lower the trellis to mow as needed.
• Late April: raise the trellis from the horizontal position to the fruiting position as soon as the flower clusters have a fixed upright position. Don't delay, or the primocanes will have too much upright growth and will be difficult to tie into the horizontal position.
• Late April through May: immediately begin tying the early emerging primocanes to the horizontal position along the training wire on the primocane side of the trellis. Use rubber bands, and handle primocanes gently as they are brittle. A minimum of 3 strong primocanes are needed; consider tying 1-2 extra primocanes. Tie primocanes at least twice a week until the primocanes reach the neighboring plant, then tip the primocanes. Primocane training will conclude in early June.
• June through August: fruit harvest. Trap for SWD, and apply protective sprays as needed.
• August through September: promptly remove floricanes as harvest ends. Tie primocane laterals into position on the fruiting side of the trellis. Space laterals 6" apart.
• Late November through early December: rotate the trellis to the horizontal position for the winter, and cover the plants with protective rowcover.

Results from the 2017 harvest season

The demonstration blackberry planting at SWRC, including the seven thornless blackberry cultivars trained to the RCA trellis, produced an initial, significant fruit crop in 2017, just one year after establishment. Data collected on the 2017 fruit yield, fruit size, and harvest season are presented in Table 1 and Figure 1. Floricane harvest began on June 9 ('Natchez', 'Prime-Ark® Traveler') and continued through August 1 ('Apache'). Primocane harvest commenced on July 26 and continued through October 6 for both 'Prime-Ark® Traveler' and 'Prime-Ark® Freedom'. Impressive first year floricane yields were noted for 'Natchez', 'Ouachita', and 'Prime-Ark® Traveler'. 'Apache' and 'Prime-Ark® Freedom' produced the largest floricane berries. First year primocane yields were modest for both 'Prime-Ark® Traveler' and 'Prime-Ark® Freedom', though the berry size of 'Prime-Ark® Freedom' was impressive. Figure 2 illustrates a peak volume of floricane berries produced among the cultivars in early July, followed by a second peak (though of less volume) in early August. A peak in volume of primocane berries was noted in late September. Worth noting is that while 'Prime-Ark® Traveler' produced berries that were smaller than several cultivars, it produced a continual summer-long harvest (June 9 to October 6), with floricane and primocane fruit production overlapping, resulting in season-long fruit yields that were the highest among all cultivars.

Table 1 Floricane yield and berry size for 7 thornless blackberry cultivars, 2017 and 2018.

* Means within columns with the same letters are not different according to Fisher's Least Significant Difference test (P < 0.05).

Figure 1 Harvest dates for 7 thornless blackberry cultivars, 2017.

Results from the 2018 harvest season

Data collected on the 2018 fruit yield, fruit size, and harvest season are presented in Table 1, and represent what we would consider to be a full crop. The sequence of ripening and the length of season were similar to 2017 (dates not shown). We noted impressive floricane yields for 'Natchez', 'Osage', 'Triple Crown', and 'Prime-Ark® Traveler'. As in 2017, 'Apache' and 'Prime-Ark® Freedom' produced the largest floricane berries. 2018 primocane yields were disappointing for both 'Prime-Ark® Traveler' and 'Prime-Ark® Freedom', and data were not collected.

Discussion

The RCA trellis requires a lot of attention from a management standpoint, and practices must be done in a timely fashion. In particular, training the primocanes to the horizontal position must be done when the shoots are small and flexible. We also strive to remove the floricanes as soon as possible after harvest, and transfer the primocane laterals to the fruiting side of the trellis. Among the cultivars under trial, 'Natchez' and 'Triple Crown' have a growth habit that works well with the RCA system. Based on two years' harvest information, 'Natchez', 'Prime-Ark® Traveler', and 'Triple Crown' would be good choices for Missouri blackberry farmers. Other challenges noted during the trial include management of SWD and Japanese beetle. Our experience with the primocane crop has been disappointing. Additional information on the study is available from the author. Farmers are welcome to visit the demonstration planting at the SWRC. Check the website http://www.webbcityfarmersmarket.com/grower-training.html for upcoming blackberry production workshops.