Alberta Barley

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Effect of rate and timing of a pre-harvest glyphosate application on seed germination, yield and quality of malting barley

Project lead:
Dr. John O’Donovan
Research Scientist
Agriculture and Agri-Food Canada

Timeline: April 2013 – March 2018



Alberta Barley funding: $37,052
Total funding from other partners: $239,934

Benefits for barley farmers
A pre-harvest application of glyphosate on malting barley can provide control of perennial weeds, but may also provide harvest management benefits by drying down the crop and mitigating the negative effects of secondary growth on seed uniformity and quality.

The project aims to assess the feasibility of, and risks associated with, using a pre-harvest glyphosate application as a dry-down on malting barley. Preliminary results indicate that pre-harvest glyphosate, when applied at the correct rate and stage, can increase yield without compromising kernel germination or resulting in unacceptable glyphosate residue in the seed. However, applying at the incorrect rate and stage sometimes resulted in reduced yields and unacceptable residue.

Recent developments
The results in 2015 indicated no yield benefits associated with pre-harvest glyphosate application. On the contrary, yield losses sometimes occurred especially when glyphosate was applied before the soft dough stage and at the high rate. This differs from previous years where some yield benefits occurred. As in previous years, germination was not affected by glyphosate, and maximum residue levels were sometimes exceeded when glyphosate was applied at the soft dough stage or high rate. In addition, glyphosate residue sometimes negatively affected growth of roots during the malting process, and levels of α-amylase. The variable and inconsistent yield benefits may not outweigh risks associated with possible reduced yield and kernel plumpness following early application, as well as unacceptable glyphosate levels in the seed, and possible effects on root growth during the malting process.

Objectives for the upcoming year
This project is ongoing until March 31 2018, and the experiment will be conducted again in 2016.

Read more:
Balancing Seed and Foliar Fungicide Treatments (January 9, 2014)

Last Updated June 2016