2019 ASHS Annual Conference

Black raspberry (Rubus occidentalis) fruit is a common sight in Midwest and Northeast U.S. farm markets and is highly prized for its excellent eating and processing qualities. High phytochemical content and antioxidant potential has also led to a large number of studies on the health benefits of black raspberry consumption, with very positive results. Unfortunately, these qualities have not led to a large increase in production in these areas, primarily due to low productivity of plantings. While price surveys find a price premium for fresh black raspberries compared to red, the relatively low yield compared to red raspberry has kept them at a disadvantage from a production standpoint. The advent of high density plantings in tree fruits and strawberries has contributed to significant increases in yield per area and thus economic viability for growers. Typical crown growth and cane production in black raspberry suggests high density plantings may be useful in increasing overall productivity in this crop. A high density planting system for black raspberry production under high tunnels was designed and implemented to compare its productivity to standard planting recommendations for high tunnel black raspberry production. Green plugs of ‘Bristol’ and ‘Jewel’ were planted at high (17,932 plants·ha^-1) and standard (6,725 plants·ha^-1) density in a high tunnel and harvested for 3 seasons. In the high density system, 2 canes from each crown were precisely trained onto a narrow V-trellis to a height of approximately 2.1 meters each year with extra canes being removed. Standard density was variable based on crown and cane vigor typically observed in black raspberry and pruning was based on standard recommendations. Full productivity was reached in the 1^st year after planting in the high density system and in the 2^nd year at standard spacing. Yield was equal to or greater in the high density system in all years and cumulative yield over 3 harvest seasons was 15.8 t·ha^-1 and 17.4 t·ha^-1 for ‘Jewel’ and ‘Bristol’, respectively. This represented a 38% and 45% yield advantage, respectively, compared to standard plant density. Fruit size was marginally negatively affected in the higher density planting. Yield compared very favorably to previous open field red and black raspberry trials as well as high tunnel floricane red raspberry yields. A high density planting with precision training shows very good potential for improving the economic viability of black raspberry production in climates similar to western NY.