The timing of glyphosate application to Black-grass was studied in detail under previous EU Set-aside rules, where pesticide application timings were restricted by calendar dates. Under the Basic Payment Scheme, (BPS) since 2015 there is no requirement for set-aside but there are situations where land is left non-cropped both as Fallow land under the Crop Diversification Rule and as Ecological Focus Areas, (EFA) under the Greening component of the BPS. There are still limitations under cross compliance and under ongoing stewardship schemes like ELS and CFE where the timing of sprays can be dictated by calendar dates. Overwintered stubbles options are sometimes not chosen by farmers because they feel it will not be possible to get good enough control of Black-grass. For example over wintered stubbles, (OWS) can be sprayed only after 15th February and extended OWS after 15th May.
Although there is discussion within the EU not to allow the application of herbicides on EFA’s this is not yet confirmed and in any case does not apply in 2017.
1. Fallow land can count as a crop under crop diversification greening as long as it is fallow between 1st May and 30th June. It must be maintained in a state suitable for grazing or cultivation and there is no restriction on the use of herbicides.
2. Fallow land for EFA must be fallow from 1st January to 30th June. Herbicides are allowed to control weeds and indeed pollen and nectar mixes or grass can be also be sown as long the grass is not harvested during the fallow period.
Both these options allow for farmers to use Roundup to tackle Black-grass in problem areas. These notes may help in deciding the best timing to minimise seed return.
The use of Roundup on Fallow land is covered by the label field of use called ’Green cover on land not being used for crop production, e.g set aside’ and up to 2160g/ha can be applied annually, either in one dose or split according to weed size and species.
September germinating Black-grass can go into stem extension in April, plants germinating in November will be slightly later. Identification of the end of tillering is not always easy as the internodes can be very short in cold conditions. If sprayed in April, it will still be necessary to re-spray fallow or non-cropped land for perennial grasses and broad-leaved weeds in June/July.
The first Black-grass plants will push up flowering heads as early as the End of April. It must be remembered it can take 6 weeks before those first seeds are mature and early maturing heads tend not to set viable seed, so don’t be tempted to rush in and spray at this stage. For every flowering stem in April and early May there are even more tillers still in the stem extension phase. This describes the growth stage when assimilates are pushing upwards very strongly to produce the flower head and translocation of glyphosate down to the roots is against the direction of that flow. Poor uptake leads to variable control.
When sprayed at this stage an initial good kill will be followed about a month later by re-growth from those tillers which were at stem extension. The re-growth typically goes on to produce more flowering stems and requires a further treatment with Roundup to stop viable seed being shed.
Excellent control is possible if spraying is delayed until full ear emergence.
Spray at full ear emergence with 1080 g ai/ha of Roundup. This means the first week in June is the ideal time. The spraying window then extends until just before the seeds are fully ripe and the foliage starts to die back. Treatment at this timing ensures no re-growth with seed viability completely controlled. The unsprayed graph shows that early emerging ears are unlikely to produce viable seed.
1080g ai/ha is the rate of Roundup required for full control of Black-grass. Using lower rates with or without additional wetters will not compensate for the reduced amount of glyphosate and results are not consistent. See table below.
For more details telephone Monsanto Hotline on 01954 717575
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©Monsanto UK Ltd. 2017(MS)