Ryegrass control: How difficult is it becoming?

Taken from Crop Production Magazine, March 2017


Whilst it often does not command  the same headlines as resistant blackgrass, difficult ryegrass has now become an equally big problem for many arable growers. To address this, Agrovista is extending its research into difficult-to-control grass-weeds with a new ryegrass trial site near Darlington, County Durham.


The work will build on other grassweed work being carried out by Agrovista, on meadowgrass in North Yorkshire and on numerous years of resistant blackgrass trials situated throughout England.


At this ryegrass trial, Agrovista R&D will be investigating a combination of cultural and chemical control methods to allow growers, whose land is affected by the weed, to continue to operate profitable cereal-based rotations.


The aim of trial is to discover what chemistry is most effective and which cultural operations work best to help take the pressure off the chemistry.


The trial field has a very high background population of difficult ryegrass and the traditional chemistry set has been failing for the past few seasons.


The main part of the field has been sown to second wheat KWS Gator. This will be treated with a matrix of 90 different chemistry combinations.This will consist of nine different pre-emergence applications, including the best existing actives plus potential new residual chemistry. All of this will be applied with and without Avadex (triallate), and will be overlaid with seven additional early post-emergence residual options. To complete the chemistry trials, most of these autumn treatments will then be over-sprayed with contact chemistry, both in the autumn and spring, to assess additional efficacy.


The untreated plots contain 870 ryegrass plants/m2, which indicates the severity of the problem. Best control from the pre-emergence sprays before any over-spraying has been 89% control of ryegrass coming from Trooper (flufenacet + pendimethalin) at 4 litres/ha together with Defy (prosulfocarb), also at 4 litres/ha.


However even this still left 95 ryegrass plants/m2 and will require a significant contribution from the follow-up treatments to provide a satisfactory outcome from the chemistry alone.


More sustainably, to complement the synthetic chemistry, a range of cultural control options are also being trialled across the site. These include various cultivations techniques including ploughing versus non-inversion tillage with different drilling dates.


This trial follows on from the success of the Agrovista blackgrass trials utilising cover-crops to condition and dry-out soil over winter to enable more consistent spring cropping on heavier land. A range of cover-crops will be evaluated to see if the technique of direct drilling the spring crop into the destroyed cover-crop with minimal soil disturbance, and hence not disturbing the seed-bank will be successful in ryegrass.


Growers will be able to assess the results for themselves at a series of open days throughout the spring and summer.


30 March 2017

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