Pre-emergent Annual Ryegrass Control

Efficacy and crop safety of various pre-emergent combinations and pipeline products for the control of annual ryegrass (ARG) in wheat.

Dumbleyung, WA, 2018

Summary

Annual ryegrass, Lolium rigidum (ARG) is a major issue in winter cropping systemsacross WA. Lack of integrated weed management (IWM), including tight rotationsand over reliance on chemical options, has seen a growing incidence of ARG withresistance to many commonly used pre-emergent herbicides.

Atrial site was established in Dumbleyung WA on the 23rd of May 2018,where rye grass was sown to emulate a medium-high weed pressure. The aim was todemonstrate and evaluate to the extended David Grays network the efficacy and cropsafety of various pre-emergent products/combinations, including EPE/PSPEapplication timings of prosulfocarb and new and pipeline chemistry (BAS684F9600) for the control of ARG.

All treatments were effective in reducing ARG populations. Findings concluded that the EPE applications of Boxer Gold and prosulfocarb were the most effective with 99% and 100% control respectively. Sakura as well as Sakura + Trifluralin were close behind, both providing 96% control. BAS684 performed well with a control of 88% and F9600 under performing with a control of 73%. The 2L rate of Trifluralin was poor with 55% control compared with the 3L rate achieving 90% control. This could potentially indicate a level of weak Group D resistance.

Methodology

Treatment List

Trial Design

Site, Crop and Application Details

*Note - 3kg of rye grass seed was purchased from seed cleaners, sown in combination with wheat at 0.3kg/Ha at seeding*

Assessment Methods

Data Analysis

All data analysis in this report was conducted using Microsoft Excel. Simple means, analysis of variance was used to determine statistical significance using the least significant difference method with a 95% confidence interval.

Results

% Control (Weed Counts)

Figure 1: 5x weed counts in a 0.5m x 0.5m quadrant as a % of untreated

All treatments performed well with the EPE applications of prosulfocarb and Boxer Gold the best, closely followed by Sakura and Sakura+Trifluralin. BAS684 performed as good as Boxer Gold but slightly behind Sakura as we saw in Merredin. F9600 started out reasonably but then ran out of residual activity by the 42 DAT assessment. There was little difference in Split vs. IBS applications of Boxer Gold, however the split application of prosulfocarb performed better than IBS.

Minimal levels of phytotoxicity were observed across the board with the F9600 treatments displaying significant bleaching symptoms. (See appendix) The Avadex Xtra + Trifluralin + Terrain treatment displayed moderate levels of phytotoxicity. However, by the 45 DAT assessment all symptoms had disappeared and no reduction in vigour detected. High winds experienced at the start of the season resulted in treated soil being blown into the furrow which may explain some of the symptoms seen.

Conclusion

This season was conducive to goodperformance from pre-emergent herbicides. We had a late start, however once theseason broke, we received rain consistently. The soil at the trial site isstrong, hence we saw great performance across the board. Some take home points:

Well timed applications ofBoxer Gold or prosulfocarb following a high rate of trifluralin providedbrilliant results on ARG. ~100%
Sakura standalone performedequally as good as Sakura + Trifluralin. However, the trifluralin is aninsurance policy for dry post-emergent conditions.
BAS684 brings an exciting and unique MOA tothe market. It has performed excellently standalone sitting 2ndbehind Sakura but just ahead of Boxer Gold across trials.
F9600 has run into someteething problems this season and seemed to run out of residual early in boththe Merredin and Dumbleyung trial.

Appendix

Site Rainfall

Photos

Please follow link for all trial photo’s:

https://www.dropbox.com/sh/two3ijvh30zkvvh/AADsrZSmcWIG8dvq0wVtTFY0a?dl=0