Managing raspberries changes with new
berry varieties, new herbicides and new
harvesting machines. Scientists at WSU’s
Northwestern Washington Research and
Extension Center at Mount Vernon are
on top of things.
MOUNT VERNON, Wash. – For decades, red raspberry growers have chemically eliminated the first crop of new shoots – “primocanes” – to ensure the vigor and fruit bearing of second-year canes. Now, scientists at WSU’s Northwestern Washington Research and Extension Center at Mount Vernon are working to determine whether that practice is still economically and environmentally viable.
 
The U.S. Environmental Protection Agency discontinued the herbicide initially used for cane burning in the late 1980s, and growers have switched to different herbicides. Harvest equipment is much more sophisticated than when the practice of cane burning was developed, and consumer preferences for raspberry cultivars also have changed over the years.
 
“In light of the advances we have made in new herbicides, new berry varieties and new harvest machinery, we are trying to determine if the tradition of burning of the primocanes is still a best practice,” said Tim Miller, WSU Extension weed scientist. He and Tom Walters, horticulturist at WSU NWREC, and graduate student Sherry Duan are in the second year of a specialty crop grant from the Washington Department of Agriculture to conduct the research.
 
Miller said another issue is determining whether yield benefits really are the result of cane burning.
 
“Is it really a better yield response or just a function of better harvesting technology?” he said.
 
The issue is not as clear cut as it may seem, Miller said. While growers could save money by not spraying to eliminate the primocanes, they could pay a price in reduced yields.
 
A secondary benefit to cane burning became apparent last winter when old raspberry canes were pruned and new canes were trained to trellis wires. Cane burning treatments in the spring reduced the labor required to train new canes by some nine hours per acre, a savings that might offset herbicide costs.