COMPARISON OF ADIOS AMBRO® TO REGISTERED
HERBICIDES IN CONVENTIONAL (IP) SOYBEAN
By University of Guelph, Ridgetown Campus (Ontario, Canada)
(Overview of 2011 trial report)






Objectives:
1. Compare the tolerance of organically grown soybean to Adios Ambros and to three commonly used conventional herbicide treatments (trifluralin (Treflan), flumetsulam + s-metolachlor (Broadstrike RC + Dual II Magnum) and imazethapyr + metribuzin (Conquest).


2. Compare the level of control that Adios Ambros will provide  to three commonly used conventional herbicide treatments.

Materials and Methods:
Soybean was planted 372 809 seeds ha-1 on June 2, 2011 at a depth of 3 cm in 75 cm rows in a Maplewood Normandale very fine sandy loam soil (% Sand: 71.2, % Silt: 16.3, % Clay: 12.5, % OM: 3.5) with pH: 6.8 and CEC: 11. The entire trial area was kept weed free until time of herbicide application with cultivation.
The trial was set up as a randomized complete block with 4 replications; plot size was 2 m wide by 10 m long.

Conventional herbicide treatments included:
1) pre-plant incorporated trifluralin (2.4 L ha-1), 2) premergence (PRE) flumetsulam + s-metolachlor (87.5 g ha-1 + 1.75 L ha-1), and 3) PREimazethapyr + metribuzin (0.42 L ha-1 + 0.8333 L ha-1). Trifluralin was applied immediately before planting an mechanically incorporated, while the PRE herbicide treatments were applied four days after planting. Herbicide treatments were applied using a CO2-pressurized backpack sprayer calibrated to deliver 200 L ha-1 aqueous solution at 241 kPa. The boom was 1.5 m wide with four ULD120-02 nozzles (ULD120-02 nozzles tip; Spraying Systems Co., Wheaton, IL.) spaced 0.5 m apart.

Adios Ambros herbicide was applied at the 1st trifoliate (June 29, 2011) and then again at first flower (July 15, 2011) stages of soybean. To accommodate the large volumes required to apply the product, Adios Ambros applications were sprinkled over the plot. We also included a treatment in which a PPI application of trifluralin (2.4 L ha-1) was followed by two applications of Adios Ambros at the 1st trifoliate (June 29, 2011) and then again at first flower (July 15, 2011) stages of soybean.

Targeted Weeds:
The following weed species were present in the trial area: common ragweed (Ambrosia artemisiifolia),
common lambsquarters (Chenopodium album), hairy crabgrass (Digitaria sanguinalis) and barnyardgrass (Echinocloa crus-galli).
An untreated check was maintained weed-free with hand weeding to allow for a determination of the potential effect of herbicide injury on soybean yield.

Results and Discussion:
Visual injury was below 10% in all treatments in the trial, and yield corresponded to visual injury ratings for most treatments. The Adios Ambros treatment caused slight (5%) injury 7 days after the second application (7 DAD), however, by 14 DAD, visual injury was not measured in any treatments.

The Adios Ambros treatment provided effective control of broadleaf weeds, but provided slightly less control of grassy weeds in the trial.

Control of common ragweed and common lambsquarters was 99% or greater at both 28 and 56 DAD.
Hairy crabgrass control was 81 and84% (at 28 and 56 DAD, respectively). Barnyardgrass control was 86 and 83% at 28 and 56 DAD, respectively.

Despite the slight decrease in grass weed control in the Adios Ambros treatment, soybean yield was comparable
to both flumetsulam + s-metolachlor and imazethapyr + metribuzin. Further research should be conducted under
more intense grass weed pressure.