Agronomy Talk

WEED MANAGEMENT BRIEF: LIBERTY AND TIME OF DAY

Published on Thursday, October 29, 2020

ABSTRACT:

  1. Liberty® applications must be targeted in the heat of the day for the greatest efficacy.

  2. Systemic herbicides such as glyphosate are not as dependent upon time of day.

  3. Liberty® + glyphosate helped give more constant grass control and applications should be targeted during the heat of the day.

 

SHOULD LIBERTY® APPLICATIONS BE TARGETED DURING BANKER HOURS?

Liberty® applications will be impacted by time of day. Sunlight influences a plant’s glutamine synthetase, which in turn, influences the effectiveness of Liberty, a glutamine synthetase inhibitor. Liberty has greater efficacy during the heat of the afternoon or “banker hours.” Systemic herbicides such as glyphosate are not as dependent upon time of day. How much does time of day influence Liberty applications? Can the addition of glyphosate help offset Liberty time of day sensitivity?

BECK’S PRACTICAL FARM RESEARCH (PFR)® RESULTS

Liberty® applications made in the afternoon resulted in an increase in waterhemp control of 13% vs. morning applications and a 10% increase in control vs. evening applications. When glyphosate was added to Liberty, the afternoon application once again did better compared to other times of the day. Waterhemp control increased by 6% in afternoon vs. morning applications, and 5% in afternoon vs. evening applications.

Grass control remained constant across the various timings. The waterhemp population was suspected to be resistant to glyphosate so we saw less than 30% control. Glyphosate is not as influenced by the time of day and we saw effective fall panicum control across the three application timings. For glyphosate-resistant weeds, Liberty is doing the heavy lifting. Therefore, Liberty + glyphosate applications must be targeted during Liberty’s optimum application windows to maximize its efficacy.

CONCLUSION:

When sprayed in the afternoon, Liberty® control increased 13% vs. other timings. Liberty + glyphosate resulted in broader spectrum weed control when weeds were sprayed at less than 4 in. tall and in the heat of the day. Target Liberty + glyphosate applications in the afternoon, since Liberty is doing the heavy lifting.

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Author: Joe Bolte

Categories: Agronomy, Agronomy Talk

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