Trials were established in late 1995 and early 1996 to evaluate several promising blackberry cultivars for fresh market production. The primary objective of the trial is to determine if one or more of these blackberry cultivars are, 1) adapted to Central Coast growing conditions, and 2) may be useful to extend the fresh blackberry harvest season to periods of higher prices.
The following cultivars are included in the trials:
| Cultivar Thorned Group | Origin |
| Roseborough | Texas |
| Shawnee | Arkansas |
| Thornless Group | |
| Arapaho | Arkansas |
| Navajo | Arkansas |
| Black Satin | Maryland |
| Chester | Illinois (USDA |
The ollalieberries and boysenberries, which are the blackberries traditionally grown in San Luis Obispo and Santa Barbara Counties, have a harvest season concentrated between late May and the first week in July. Fresh blackberry prices are highest from September to June in a typical year. There are additional marketing benefits to those growers who have fresh blackberries available for an extended shipping season because buyers will return confident that fruit is available.
None of the blackberry cultivars in the trial produced in the establishment year. Each of these cultivars grew vigorously and established a strong plant skeleton on which to produce fruit. Each of these cultivars are more erect types and require little training. Black Satin and Chester are semi-trailing and have somewhat longer canes which require some support. All of the cultivars in the trial received ample chilling for normal production in coastal San Luis Obispo County during the 1996-97 season. Production began in April 1997. Roseborough was the earliest producing cultivar with good fruit volume starting the last week in April in 1997.
The Roseborough cultivar is extremely vigorous and erect but also quite thorny. Roseborough continued to produce into late May. In future seasons, it may be possible to further extend the harvest season of Roseborough with pruning management.
Arapaho was the next earliest cultivar behind Roseborough and the earliest of the thorn-free cultivars. Arapaho began production in mid-May. Shawnee was slightly later and Navajo followed 10-15 days later. The thorn-free cultivars produce over a reasonably long season, and the thorn-free trait dramatically eases blackberry management and pruning. Growers wishing to plant and manage only thorn-free cultivars will need to forego the earliest (late-April) harvest.
Ollalieberries and boysenberries are also well adapted and productive and very flavorful. They will produce from late May to early July in a typical year. Black Satin began producing about July 7 with large, flavorful fruit. Chester and Choctaw began 7 to 10 days behind Black Satin. Arapaho, Navajo, Chester, and Black Satin are continuing to produce good yields of high quality fruit as I write in late September, and the abundant green fruit on these plants indicates that they will produce well into October. I will sum up the overall production season in a later article.
All of the cultivars have produced acceptable volumes of attractive and flavorful fruit. Yields from second year plants have averaged from 6 oz. to over 1 lb. of fruit per plant per week. Plants are spaced 3 feet apart in rows 10 feet apart for a total plant population of 1,452 plants per acre.
The results from on-going red raspberry trials have also been favorable. The Autumn Bliss cultivar continues to be the earliest of the red raspberries, and with good management continues to produce from late April into December. This is important because we can now expect to produce high yields of good quality blackberries and raspberries on the Central Coast over a long marketing season.
Blackberry consumption in the US is approximately one-tenth that of raspberries which in turn is approximately one-tenth that of strawberries. Blackberries and raspberries can be quite profitable, however, especially if you are able to harvest and ship over an extended season. Also the availability of both raspberries and blackberries may aid in more consistent sales of each.