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WestVic Dairy News - March 2010 Edition

Some tips for Barley Grass Control

By Janet Sloan, Dairy Extension Officer, Department of Primary Industries, Warrnambool

At a recent discussion group the topic of barley grass control was raised. Many farmers have also noticed the increased prevalence of this weed in their pastures this season. Speaker at the group, Phil Jobling, Nufarm Sales Manager & National Grassmanship Coordinator gave some useful information on how to tackle this troublesome weed.

Phil said that barley grass seed will stay viable in the soil for 2-4 years, hence a 2-3 year control program is required to reduce the seed bank if you really want to get on top of it. He also suggested that rather than treat the whole farm in one go, it is often more practical to target specific areas and achieve good long-term control in this smaller area.

Phil’s autumn management option:

  • Badly infested paddocks should be tickled up (using harrows or similar equipment) prior to the break, to help stimulate a good germination of the barley grass seed.
  • Once 1-2 leaves have emerged, Phil suggests to spray with glyphosphate (always read and follow the chemical product label to ensure correct application rates are used as well as Do Not and/or critical statements are abided by), then drill in an annual or Italian ryegrass to provide competition to any remaining barley grass yet to emerge.
  • Consideration should be given to the type and cost of the seed used, as you will need to kill off the barley grass in the spring by spraying the whole paddock, using one of the 3 options in the spring management section below.

Phil’s spring management options:
Spring management of barley grass is critical, Barley grass must not be allowed to set seed. The most effective method of achieving this is by chemical control. Mechanical control (topping) will have little effect as the plants will just keep shooting up seed heads until they die in late spring. They can also develop seed heads which are horizontal to the ground, making mechanical topping ineffective.

Early silage (late Sept.) will remove some seed heads and the regrowth will be at a similar stage and ideal for chemical control. Chemical control in the spring is about killing off the plants and preventing any seed set.

There are three possible strategies:

  1. Completely kill all plants, using glyphosphate (see label for rates and timing). This should be done just prior to silage cut (up to 4 days before cutting) or after silage cut (allowing 14-21 days for the paddock to freshen up before applying). This allows the paddock to be either left to fallow till autumn or to be sown down with a summer forage crop. (Note it is critical to understand and follow withholding periods (WHPs) for any chemical product used.)
  2. Spray Top the barley grass with light rates of glyphosphate (again follow label directions and observe WHPs) at the time the barley grass is flowering. This will usually sterilize the seeds and prevent the seed heads from becoming sharp/brittle.
  3. “Hay freeze” the plants, where appropriate rates of glyphosphate are used to stop any further development of the plants without actually killing them. The advantage of strategy is that the feed quality is preserved –a bit like standing hay, yet the seed set on the barley grass is stopped. The difficulty with this approach is its variability of success as factors such as climatic conditions, plant stress levels and water quality can affect the level of success achieved.

For paddocks only partly effected with barley grass:

The aim is to stop the weeds set seed and stop the infested area getting bigger. Autumn and spring management is the same as above, however there is some other factor’s which need to be considered due the smaller scale of the problem. A small boom sprayer could be quite helpful.

Spraying out in the autumn and drilling in an annual or Italian can create additional management challenges, due the treated area of the paddock not being able to be grazed (i.e. pugging damage risk in winter) and the remaining part of the paddock needing to be grazed. Controlling barley grass patches in the spring is often the better choice, as the area can be sprayed out and left fallow over the summer.

A short term ryegrass can be sown dry in the following autumn, saving time to first grazing and more uniformity of feed across the paddock, if control has been successful. Otherwise it would be wiser to implement an autumn management strategy, with some creative strip fencing around the patches to reduce the chances of pugging damage over winter.

In summary then, now is a good time to start planning your strategy to tackle this weed. Have a chat with your local chemical reseller and explore your options to control this troublesome weed this year.

The advice provided in this document is intended as a source of information only. Always thoroughly read the product label before using any agricultural or veterinary chemical.

The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence, which may arise from you relying on any information in this publication.