The performance of alternative knockdown options for managing ryegrass (Lolium rigidum) populations with glyphosate resistance has been investigated by Clovercrest Consulting, in collaboration with Birchip Cropping Group Inc. (BCG).
Herbicide resistant weeds are becoming increasingly common, and resistant weeds bring new challenges to the farm business, particularly for the bottom line.
Cropping ‘out of the drum’ is not a sustainable practice. The cost of production has increased significantly over the last decade, and a movement to no-till farming systems has seen a subsequent rise in herbicide resistance numbers, in particular ryegrass.
A field research trial was established by Clovercrest Consulting at Kaniva in the West Wimmera as part of the GRDC Southern region agronomy trial extension network project CLO00001, and BCG is working with Clovercrest Consulting on the project.
The trial aims to address the following;
a) Identify options for the control of glyphosate resistant ryegrass,
b) Increase grower awareness around rotating the various knockdown options pre-sowing and;
c) Demonstrate the different application requirements for alternative knockdown options.
BCG researcher Kelly Angel is working with Simon Mock of Clovercrest Consulting and she said the trial examined a broad range of herbicide options which aimed to control ryegrass plant counts as high as 1676 plants/m2.
“It’s imperative to investigate this research, as chemical costs can blow out quite easily, have very little effect and consequently impinge on a growers profitability,”
“Knockdown options being compared were glyphosate alone, double knock (glyphosate followed by Gramoxone®), Gramoxone® alone, Para-Trooper®, Alliance®, Boxer Gold® + Gramoxone®, Goal® + Gramoxone®, and experimental chemistry, all ranging between $4.70/ha to $48.95/ha,”
Applications of herbicides were targeted when ryegrass was between two-leaf and early tillering and plant count assessments were carried out seven, 14, 28 and 42 days after application.
Initial results have revealed a 35% resistance status to glyphosate at 1L/ha and 25% at 1.5L/ha but was fully susceptible at 2L/ha.
“This research highlights the importance of understanding your resistance status (if you have one) to help improve crop rotations and explore non-herbicide control options in the farming system eg. hay,” she said.
And as much as product selection is important, application, water rates, nozzle selection and spray timing all need to be considered as they can influence the efficacy of knockdown sprays.
The results generated from this trial will be analysed and presented in the members only BCG Season Research Results compendium produced at the end of the season. For more information phone Clovercrest Consultant Simon Mock on 0429 802 493 or BCG researcher Kelly Angel on (03) 5492 2787.
