Skip to main content
ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Publications at this Location » Publication #316742

Title: Method to reduce low temperature stress (LTS) in red raspberry (Rubus idaeus L.)

Author
item NESTBY, ROLF - Bioforsk
item Takeda, Fumiomi

Submitted to: Journal of Berry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2015
Publication Date: 12/25/2015
Citation: Nestby, R., Takeda, F. 2015. Method to reduce low temperature stress (LTS) in red raspberry (Rubus idaeus L.). Journal of Berry Research. 5:219-230.

Interpretive Summary: In Norway and other Nordic regions, the floricanes of red raspberries often suffer 20 to 30 percent injury from exposure to extremely low temperatures. We studied the effect of bending the floricanes of ‘Glen Ample’, ‘Stiora’ and KV91-39-7 red raspberries close to the ground and covering canes on winter injury and yield. The canes were trained to a rotating cross-arm (RCA) trellis system and covered with two layers of polyethylene (Agricover) sheets. In addition, supplemental heat was provided when the temperature dropped below critical levels (-15 degrees C in Dec-March, -10 degrees C in March, -5 degrees C in April). Bending and covering of canes reduced bud injury because of improved temperature conditions under the cover. Cane bending and heating under the winter cover at critical temperatures reduced freezing injury of buds for all cultivars, and tended to increase yield of covered and heated plots compared with no heating for ‘Stiora’ and KV-91-39-7. This research demonstrated that by bending the canes close to the ground and covering them with a rowcover in winter, and adding supplemental heat during the coldest nights provides a means to improve and expand raspberry production in Nordic countries.

Technical Abstract: In Norway and other Nordic regions, the floricanes of red raspberries often suffer 20 to 30 percent injury from exposures to extremely low temperatures. We studied from 2011 to 2014 to determine the effect of bending the floricanes of ‘Glen Ample’, ‘Stiora’ and KV91-39-7 red raspberries close to the ground and covering canes on winter injury and yield. The canes were trained to a rotating cross-arm (RCA) trellis system and covered with two layers of polyethylene (Agricover) sheets. In addition, supplemental heat was provided when the temperature dropped below critical levels (-15 degrees C Dec-March, -10 degrees C March, -5 degrees C April). Bending and covering of canes reduced bud injury because of improved temperature conditions under the cover. However, there were no interaction effects between year and bending treatment or between clone and bending treatment for total yield and fruit size. Cane bending and heating under the winter cover at critical temperatures reduced freezing injury of buds for all cultivars, and tended to increase yield of covered and heated plots compared with no heating for ‘Stiora’ and KV-91-39-7, but not for ‘Glen Ample. One reason for this difference could be that the laterals of ‘Stiora’ especially could not handle the berry load and were hanging on top of each other like tiles, unless the canes were lifted to vertical immediately after removal of winter cover. ‘Glen Ample’ managed to keep its laterals closer to a horizontal position. The experiments show that bending raspberry canes to avoid freezing injury was possible without much visible injury to the cane if the bending was undertaken carefully using a RCA trellis. However, standard trellising with erect canes improved fruit yield. This was especially the case for ‘Stiora’ that had weak laterals one level hanging over the next like a tile, while the other cultivars had stronger laterals giving a more airy pattern. It was found that more cane buds were torn off because of trellising, especially in ‘Glen Ample’, reducing the amount of buds by approximately two percent compared to canes in an erect position. The method also has a second aspect worth considering. Positioning the laterals in one direction could make harvesting easier, which could be considered to reduce logistic costs. However, this method could reduce yield unless some actions are taken to avoid tiling of laterals that are suggested to cause reduced pollination and photosynthesis. Also, it is probably not necessary to lower the canes below horizontal during winter since bending to the ground could increase the cane injury. There is also a potential for growing blackberries using the same method as suggested for primocane raspberries.