Project Abstract

Reglone with a surfactant (usually Li700) is the common chemical combination used to desiccate seed alfalfa crops in Southern Alberta. For organic systems of seed alfalfa production there is no chemical options for desiccation.

Also, there are many surfactants on the market that can improve the performance of a desiccation chemical. For these reasons this study was designed to test the efficacy of Acetic acid in combination with surfactants to desiccate seed alfalfa.

The goal is to increase the options for growers, especially organic growers, and possibly improve harvestability and/or yield for seed alfalfa producers. Farming Smarter staff applied Reglone Ion and Acetic acid alone and with added Li700 and HiActivate surfactants when alfalfa seed crops were mature.

Reglone was applied (unintentionally) at 4x rate and acidic acid at 20% v/v using 160 L/acre water volume. We found Reglone was the most effective for drying down the crop, and addition of surfactants to Reglone did not improve dry-down performance. Added surfactant with Acetic acid increased its effectiveness, with HiActivate drying down the crop better than Li700.

Image 1: General spraying picture of Custom Research Crew, June 14, 2021.

Methods

Desiccation spraying was carried out by Farming Smarter once the crop was fully mature. Each trial was sprayed at dawn or dusk, Rosemary in the evenings and Lethbridge in the early mornings before sunrise. This allowed the chemicals to be absorbed into the leaves of the Alfalfa before the sun could activate or evaporate the water on the leaf surface (making them less effective).

Table 1 outlines the trial activity timeline. A visual efficacy rating was conducted on a scale of 0-100%, where 0 would be healthy plants not affected by the chemical and 100 would be brown, dry plants completed dried down due to the chemical. Photographs of each plot were taken right before harvest. The pictures were run through the EasyLeaf program to detect green plant material, referred to as greenness, and evaluate the efficacy of the treatments. Weights were collected for each plot, dockage weighed, and a corrected yield was calculated.

A linear model with ANOVA statistics, using 95% confidence, were used to assess differences between the treatments. Each trial was designed with 2.5-meter by 6-meter plots, leaving a small buffer between each plot in each replication. A randomized complete block design was used with 4 blocks (replications). Each block included each herbicide treatment (Fig. 1). A water volume of 160 L/acre was sprayed with a 2 m handheld CO2 sprayer.

Treatments
	Reglone Ion
	Reglone Ion + Li700
	Reglone Ion + HiActivate
	Acetic acid (20%)
	Acetic acid + Li700
	Acetic acid + HiActivate

Table 1: Research Activities Timeline

Figure 1: Trial diagram for Lethbridge field, illustrating the design methods of each trial.