Organic Blackberry Cultivar Trials at High Elevation and in High pH Soil in the Southwestern United States

Two semi–erect, three erect floricane-fruiting and one primocane-fruiting blackberry ( RubusL. subgenus RubusWatson) cultivars were evaluated in high tunnels and in the field at Alcalde, NM. Semi–erect cultivars Triple Crown and Chester Thornless were planted at 1.5 × 2.5 m in a 5.0 × 12.2 m high tunnel with an identical field planting. Erect cultivars Ouachita, Natchez and Navaho, and primocane-fruiting cultivar Prime-Ark® 45 were planted at 0.6 × 1.7 m in another 5.0 × 12.2 m high tunnel with an identical field planting. Comparing all cultivars, yield of floricane-fruiting cultivars was reduced by winter damage while the primocane-fruiting cultivar Prime-Ark® 45 had reliable fall crops in the high tunnel each year in northern New Mexico. Based on four winters’ weather, canes of semi–erect and erect blackberry cultivars overwintered well when mid-winter temperatures dropped to -15 °C, but canes were damaged when temperatures reached -20 °C. ‘Chester Thornless’ was more cold hardy than ‘Triple Crown’, and ‘Ouachita’ was more cold hardy than ‘Navaho’ and ‘Natchez’ in the field. ‘Triple Crown’ produced 1-1.5 times more yield than ‘Chester Thornless’ in the high tunnel and in the field, while ‘Ouachita’ had the highest yield in 2015 and the highest cumulative yield from 2012–2015 among the three erect cultivars tested in the high tunnel, while in the field ‘Natchez’ had the highest cumulative yield. ‘Prime-Ark® 45’ produced well in the fall in the high tunnel but not in the field. ‘Navaho’ had small plants and low yields both in the high tunnel and in the field. In northern New Mexico or similar areas with a short growing season, ‘Triple Crown’, ‘Ouachita’, ‘Natchez’ and ‘Prime-Ark® 45’ are recommended for high tunnels while ‘Triple Crown’, ‘Natchez’, and ‘Ouachita’ are recommended for field planting.