High Tunnel and Open Field Production of Floricane- and Primocane-fruiting Raspberry Cultivars

Identical trials were conducted in a multibay high tunnel and an adjacent open field in southwestern Michigan to compare primocane-fruiting cultivars (Autumn Britten, Caroline, Chinook, Heritage) and floricane-fruiting cultivars (Canby, Encore, Heritage, Nova) of red raspberry (Rubus idaeus). Floricane-fruiting plots of ‘Heritage’ were pruned to produce fruit on floricanes and primocanes (double cropping). The most productive cultivars in both environments were ‘Nova’ and ‘Canby’ (floricane) and ‘Caroline’ and ‘Heritage’ (primocane). These cultivars produced annual yields of 5.5 kg·m−1 row in the tunnel and 2.5 kg·m−1 row in the field. The order of primocane harvest (earliest to latest) was the same in the tunnel and field: ‘Autumn Britten’, ‘Caroline’, ‘Chinook’, and ‘Heritage’. Cultivars with the greatest average berry weight in the tunnel and field were Encore and Nova (floricane) and Autumn Britten and Caroline (primocane). ‘Chinook’ and ‘Autumn Britten’ tended to have the highest incidence of gray mold (Botrytis cinerea) of primocane-fruiting cultivars, but incidence was similar in floricane cultivars. Overall mold incidence was 1% in the tunnel and 13% in the field. Leaf spot (Sphaerulina rubi), cane anthracnose (Elsinoe veneta), spur blight (Didymella applanata), and botrytis cane blight (B. cinerea) were common in the field but absent in tunnel. Phytonutritional analyses of primocane fruit indicated that genotype differences were not consistent across the two environments. Relative cultivar characteristics (harvest season, yield, berry quality) were similar in the field and tunnels, but the tunnel environment tended to increase plant vigor, yield, and fruit quality and suppress several diseases.

Pruning Practices Affect Yield, Yield Components, and Their Distribution in `Royalty' Purple Raspberry

A factorial arrangement of 48 treatments was used to evaluate the effects of cane density, time of cane density adjustment, primocane tipping, and cane or branch length on yield components in `Royalty' purple raspberry [(Rubus occidentals × R. idaeus) × R. idaeus] over 2 years. Yield was positively related to cane density and length, while fruit size and fruit count per lateral were negatively related to cane and branch length. When branches on tipped canes were shortened in late winter, more buds became fruitful at the proximal end of the branch, but fruiting laterals did not have more flowers or fruit. Fruiting laterals were longer on shortened canes, resulting in a decrease in the fruit: wood ratio. Plants performed similarly whether floricane density was adjusted in late winter orprimocane density was adjusted in late spring. Although potential yield was higher when primocanes were tipped in late spring, harvesting was more difficult because of branch orientation, and the incidence of cane blight infection was higher. Our study suggests that maintaining at least 12 canes per meter of row, avoiding primocane tipping, retaining full cane length, and providing adequate light, moisture, and nutrient levels can result in high yields of large fruit.

Didymella applanata. [Descriptions of Fungi and Bacteria].

A description is provided for Didymella applanata. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Rubus idaeus (raspberry), R. fruticosus (blackberry) and R. ursinus var. loganobaccus (loganberry). Also on R. australis. DISEASE: Spur blight (in USA) and sometimes referred to as cane blight (in Europe). Early symptoms are purplish blotches mainly on the epidermis at the nodes round the base of leaves and sometimes between the nodes on the lower portions of the stems. As the disease progresses the blotches increase in size extending upward and downward along the cane and sometimes the lesions coalesce to form a discoloured cane. Didymella applanata has been reported to cause dieback (2, 457; 32, 572; 41, 353) and witches' brooms (2, 457). GEOGRAPHICAL DISTRIBUTION: Africa, Asia, Australasia & Oceania, Europe and North America (CMI Map 72, ed. 3, 1977). New records not mapped are: Europe (Czechoslovakia). TRANSMISSION: By ascospores and conidia released during wet or extremely moist conditions (10, 530; 55, 1875; Wormald, 1939; Converse, 1966). In the UK small numbers of ascospores have been trapped in raspberry plantations throughout the summer and early autumn when RH exceeded 70% and temperatures above 12°C prevailed for at least 12 h (37, 201). It invades both unwounded and wounded tissues (9, 117-118; 10, 531). Entry into canes is also achieved through wounds created by Diplosis (gall fly) in Germany (11, 381) and by Thomasiniana theebaldi (midge) (28, 340; 32, 86; 34, 728; 39, 120; 43, 519). As a rule the fungus invades all regions of the cortex except the cork which acts as a barrier (9, 117-118; 10, 531; 11, 381) but it has been known to cause deeper lesions on midge larval feeding areas and frequently penetrates the stem to the pith and kills the cane (32, 86).