Flax Herbicide Evaluation
Jeannette Gaultier BASF
Eric Fridfinnson MFGA
Scott Chalmers, WADO
Nirmal Hari, PESAI
To compare the efficacy of Authority (standard treatment) to Armezon
(experimental treatment) for crop and weed efficacy, and to observe any safety
concerns with herbicide combinations.
Interestingly there were no flax injuries with Authority + Mextrol option but Armezon in combination
with Mextrol caused injuries. Based on these preliminary findings, this combination should be avoided in
real farm situations unless if further studies with reduced applications rates of Mextrol can prove
otherwise. Armezon on its own did not seem to show crop injury, but it stunted the height of flax, which
could reduce seed yield. Arborg was the only site that showed yield loss based on herbicide use in
general. At this site, Armezon showed yield loss both in sole use, and in combination with Mextrol. The
study will be conducted again in 2021 before recommendations can be made available for registration of
Armezon in flax. There might be need to consider reducing Mextrol application rates when used in
combination with Armezon in order to address crop injury concerns.
Flax (Linum usitatissimum) is an important crop known for its value in food and fibre industrial markets
around the world. However, flax has a low competitive ability with weeds compared to other crops is
recommended to be grown on relatively weed free fields. Various weed management strategies that
include; competitive varieties, early seeding, increased seeding rates and the use of pre and post
emergence herbicides can help to effectively control weeds and reduce yield loss than employing one
control factor alone (Kurtenbach et al., 2019). Preemergence weed control is crucial in flax to reduce
yield loss since flax is a weak competitor with weeds (Berglund and Zollinger, 2007). Post emergence
weed control, if done soon after weed emergence to small weeds and flax seedlings, usually results in
better control and allow more time for flax recovery from possible herbicide injury than when herbicides
are applied to larger weeds and flax later on in the growing season. There is currently a challenge in
herbicide options for flax as a result of herbicide resistance. Furthermore, concerns for herbicide injury
on flax with the use of different herbicide combinations need to be examined. There is need to
investigate possible alternative options, combinations and timing of application for control of both
broad leaf weeds and grasses. Armezon® herbicide, which is classified as Group 27, is an effective tankmix option that is currently registered as a post emergence herbicide for control tough broad leaf weeds
and grasses in corn and has potential for use in flax for control of Group 1 resistant grasses due to its
suppression effect on grasses (Table 1). Currently, the herbicide is not registered for use in flax but
extensive field trials can provide for a pathway to registration and this will benefit flax producers.
Therefore, this study seeks to evaluate several herbicides including Authority, Mextrol, Koril, Select and
experimental Armezon used alone or tank mixed with compatible herbicides in flax in order to
effectively control resistant weeds and reduce yield losses as a result. The study also seeks to evaluate
any safety concerns with the use of different herbicide mixes in flax.