Mapping, rogueing and controlling grass weeds

As fungicide applications get under control and farmers prepare machinery for harvest, this time of year is also a time to take a stroll to the fields and keep an eye out for grass weeds.

If species like brome, black grass, wild oats or canary grass are left for the season the problem will become bigger as seeds will be shed for the following crop.

To put things into perspective 1 plant/m²/ha can result in the return of six million seeds of black grass. If there are 12 plants/m²/ha this can result in a 5% yield loss.

As chemistry goes off the market and resistance builds up to certain herbicides cultural control is one of the biggest tools which can be used in the control of grass weeds.

Chemical control of black grass is limited and the weed has the potential to devastate tillage fields where it takes hold in crops.

There are more chemical options available for the control of brome, but it should still be stopped before it gets out of control. Cultural methods of control are essential in combating grass weeds.

Wild oats and canary grass which have not been sprayed should also be tackled and pulled before going to seed.

If plants like black grass have become too strong and plentiful to pull then glyphosate may be applied before the plant goes to seed. Some farmers choose to cut an area if it is small in size to ensure that seeds do not get to develop.

It is also important to pay attention to field margins and roadways. Where grass weeds are present the seed can make its way into the crop for following seasons.

Map grass weeds

It may also be a good idea to map grass weeds on your farm. Noting where grass weeds are present in a diary or on a map can help to keep these weeds under control as you may be able to see if pulling the weed the year before stopped it spreading or you will see if the chemistry used was effective.

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