'Niwot' Primocane-Fruit Black Raspberry Update
Posted: December 8, 2014
Fall of 2013 was the first fall for fruiting our 'Niwot' primocane-fruiting black raspberry in tunnels, and yields were decent at a little under a half-pound per linear foot of row, or about 2400 pounds per acre. It looked like there was a lot of cane that could produce summer fruit, so in 2014, we pruned it as if it were a floricane-fruiter, though because the laterals were quite stocky, we left more wood than usual – anything thicker than pencil thickness was kept.
The summer yields were really impressive, in part because the summer harvest season lasted an entire month, from June 25 through July 25. During this time, total yields added up to the equivalent of about 6300 pounds of fruit per acre, with 80% of that fruit being marketable. Fruit size was also good, averaging 1.7 grams per berry. The main problem that caused fruit to be unmarketable was double receptacles, which caused the berries to break apart into two halves which for some reason, didn't ripen at the same rate.
Fruit continued to trickle in until the fall yields on the primocanes started to pick up around August 18. Fall harvest continued at a lower rate than in the summer, with the equivalent of another 1900 lb of fruit per acre produced over the following month, and then additional fruit trickled in. During the month-long main fall harvest period, berries were larger than on the floricanes, averaging 2.4 grams per berry, but only 70% of the fruit was marketable, thanks to spotted wing drosophila moving in.
One disease susceptibility that is a little troubling is that there was a fall rust problem on the leaves, though the fruit wasn't affected. All-in-all, this variety is worth a look for anyone who is interested in producing black raspberries, and if it is summer-cropped, the majority of the fruit is picked before spotted wing drosophila is present.