2017 ASHS Annual Conference

Primocane-fruiting red raspberries (Rubus idaeus L.) avoid winter injury by fruiting on first year canes, but fruit production is later than needed for some local markets in the Intermountain West. Early spring heat could help to maximize primocane growth and promote earlier production. We conducted a study to compare early heating with high tunnels to field production using two different primocane raspberry cultivars, Caroline and Josephine. High tunnel plastic was installed 17 March, and removed by 5 May. As fruit began to ripen, the high tunnel frames were covered with shade cloth to minimize sunburned drupelets. Field plots remained unshaded. Tunnel and field treatments were compared for yield, fruiting season, fruit size and quality. The tunnel treatments advanced primocane growth by up to 55 cm (18 May, Caroline), with early harvest advanced by approximately 24 days for ‘Caroline’ and 19 days for ‘Josephine’. High tunnels also increased marketable yield percentage, but had no effect on average berry size. Early spring heat with high tunnels represent an opportunity to shift primocane raspberry production earlier in the season to address local market needs in high-elevation continental climates.