RESPONSE OF HIGHBUSH BLUEBERRIES TO POSTEMERGENT HERBICIDES

Several postemergent herbicides are labeled for use on Michigan blueberries, and can be combined with preemergent herbicides applied in the spring to kill emerged weeds.
However, the green bark at the base of young canes can be injured if exposed to spray, and the long-term consequences of this injury on cane renewal and overall bush health are not clear.
Mature ‘Bluecrop’ bushes in Benton Harbor, Mich. were treated each May from 2004 to 2007 with 1) glyphosate at 1.1 kg/ha (Roundup Ultra® 4L), 2) paraquat at 0.84 kg/ha (Gramoxone Max™ 3L), 3) carfentrazone at 0.03 kg/ha (Aim® 1.9EC), 4) glufosinate at 1.1 kg/ha (Rely® 1L) or 5) no postemergent treatment (control). Herbicides were sprayed in a 1.5 m wide swath beneath the bushes so that the spray contacted the bottom of bushes.
The number of 1, 2 and greater year-old canes were counted each spring.
Canes were defined as shoots and branches originating less than 10 cm from the ground.
Each herbicide caused injury to young canes and leaves, but over four years, the numbers of young and older canes were not affected by treatments.

IX International Vaccinium Symposium

E.J. Hanson

carfentrazone, glufosinate, glyphosate, paraquat, Vaccinium corymbosum

https://doi.org/10.17660/ActaHortic.2009.810.55