Glufosinate is an important herbicide for weed control in California orchards. Although glufosinate is generally used as a contact herbicide, almond growers have expressed concern about injury to young almond trees suspected to be from translocation of the herbicide. The objective of this study was to evaluate uptake and translocation of glufosinate, in comparison to glyphosate, in young almond trees. 14C-radiolabeled glufosinate or glyphosate was applied to leaf, green bark, or old bark (rootstock) of two-year-old almond nursery stock. Tissues were destructively harvested 1, 3, and 7 days after treatment. Absorption of glyphosate was greater than glufosinate regardless of application site. Most of the herbicide applied to old bark remained in the treated area (52% of the glufosinate and 94% of the glyphosate). In contrast, when applied to leaf or green bark, only 17 to 19% of the glufosinate and 32 to 43% of the glyphosate remained in the treated area. For both herbicides, 14C was recovered in roots, which suggests that there is long distance translocation of glufosinate that is comparable to glyphosate. However, more research is needed to determine whether the radioactivity recovered in almond roots was in the form of the parent compound or a metabolite. This work addresses almond grower concerns and increases our understanding of the mobility of glufosinate in woody specialty crops in California.

Evaluation of glufosinate and glyphosate translocation in young almond (<i>Prunus dulcis</i>) trees

246th National Meeting (2013)

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Evaluation of glufosinate and glyphosate translocation in young almond (Prunus dulcis) trees