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Tillage Update - 8th October

Michael Hennessy, Tillage Specialist says there is still plenty of time to plant winter cereals. He looks at post emergence weed control in winter crops. He warns that all farmers with black grass should be ultra cautious and do everything in their power to eliminate that weed from their farms.

The past few days has all but stopped activity in fields with almost all soils at or above soil moisture holding capacity.   It will take most soils a few days to dry out but there is still plenty of time to plant winter cereals.  Up until the break in weather good progress was made in many parts of the country with up to 40% planted in some areas.   It's expected that, if the weather cooperates, the area of winter cereals planted this year will be similar to 2019. 

Post emergence weed control  

Focus will now turn to post emergence weed control in winter crops.   A high proportion of oilseed rape sown in September did not receive a pre-emergent herbicide. As these crops are a little backward good weed control is even more important in these crops. The main target for control is initially volunteer cereals but other broad-leaved weeds including charlock also need to be controlled.  Where volunteer cereals are numerous an application of a graminicide such as Falcon or Stratos etc. should be applied before weed competition impacts on crop development.

Clearfield varieties have specific herbicide options for charlock and other brassica weed control however normal varieties will have to rely on the herbicide Salsa for control of brassica weeds. This herbicide needs good growing conditions and critically a small weed to achieve successful control.  So there is only a narrow window of opportunity left to use this herbicide. This herbicide controls a narrow weed spectrum and may need additional help to control a broader range of weeds in many fields. There is also of course an option to delay the herbicide application, where the weed challenge is not high, until November when the oilseed rape plant is more developed and the soil temperatures decrease.   Astrokerb can be very successful however, due to restrictions on the herbicide used, straw cannot be used with livestock. 

For further details on these control options listen to this week's Teagasc Tillage Edge podcast with crops expert Ciaran Collins who shares his agronomic advice in this area. Dr Stephen Kildea, a plant pathologist in Teagasc and Ciaran Collins, a crops specialist in Teagasc joined Michael Hennessy on this week’s Tillage Edge podcast to discuss weed control at this time of year.

For more episodes and information from the Tillage Edge podcast go to https://www.teagasc.ie/crops/crops/the-tillage-edge-podcast/

Planning for post emergence weed control in winter cereals should be happening on farms at the moment as the earliest planted crops are now emerging.   The target is to apply the herbicide with an insecticide at the two to three leaf stage of the crop.   It is critical to use the knowledge of the weeds in the field along with walking crops to assess the weed species and weed size before choosing the herbicide.   Control will be based around five main herbicides actives; pendimethalin, flufenacet, diflufenican, chlorotoluron and SU herbicides (Pacifica and Broadway Star).   Weed control in winter cereals is more difficult now as we have to deal with resistant broad leaves such as chickweed and poppy and also more challenges from grass weeds such as sterile brome, canary grass, Italian ryegrass and black grass.   


On a point of note; if you have a field with blackgrass this should not be in tillage this year but be placed and actively managed in grass for the next number of years.   Don't let anyone convince you there are herbicide options to control blackgrass whereby it can be eliminated from your farm over the next number of years, it's simply not true!   Irish farmers can/should learn from years of experience in the UK farmer who have utterly failed to halt the spread of blackgrass to the point where the weed has forced the reshaping of the cropping structure across the main arable areas of the country.  All farmers with black grass should be ultra cautious and do everything in their power to eliminate the weed from their farms or blackgrass will ensure the tillage operation on the farm is unprofitable within a short number of years.

Options for general weed control (with non-resistant weeds and no specific grass weed challenge) include Flight 4.0L/ha or Defy  2.0L/ha plus DFF 0.1L/ha or Tower 2.0L/ha or Bacara Triple 0.7 L.ha.  Check labels carefully before applying.  Further details are available on the Teagasc Crop Report (https://teagasccropreport.ie/ where registration and specific client subscription fee is necessary for access).