Project Abstract

Alfalfa weevils are a pest in seed alfalfa production because the larvae eat the flower buds off the plants. High population of Alfalfa weevil can substantially decrease yield.

In the last few years, Alfalfa Weevil larvae have become more resistant to common insecticides used control them, especially in Rosemary Alberta and surrounding area. Therefore, alfalfa seed growers of this region are experiencing higher populations that are more difficult to control.

This study focuses on testing several insecticide options for farmers, aiming to help them protect their crops from this formidable pest. Farming Smarter applied multiple insecticides to seed alfalfa when alfalfa weevils were infesting the crop. Researchers evaluated the efficacy of the insecticides by sweeping each plot (10 sweeps) and counting the larvae of the Alfalfa weevil.

Assail and Entrust on average over the 4 weevil count periods show lower weevil populations, with Assail 1x and 2x, and Entrust 2x showing lower weevil counts, especially at 4 days after application (DAA). Confident yield benefits were not found for any of the treatments.

Image 1: Alfalfa Weevil larvae in the palm of our hand, June 14, 2021.

Methods

Full breakdown of project methods

Farming Smarter staff applied the insecticides at 40 L/acre water volume at half, normal, and double label rates of each insecticide, using CO2 propelled hand booms. The middle 2 meters were sprayed, leaving a 2-meter buffer on either side of the plots. Spraying occurred when the larvae were actively hatching.

Farming Smarter closely collaborated with Alfalfa Seed Commission to time the pesticide application appropriately. Plots were swept right before spraying and larvae were counted. This was repeated at 4, 7, and 11 days after application (DAA). Yield and dockage were gathered from the middle 2-meters of each plot (treated area).

Statistical analysis was completed using a linear model with ANOVA statistics, using 95% confidence, to assess treatment effects. Table 1 outlines the timeline of each research activity.

 Table 1: Research Activities Timeline

Figure 1: Trial Diagram for Richard's field, illustrating the design methods of each trial.