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Tillage Update 8th July 2021

This week's tillage update has information on pre-harvest desiccation of winter oilseed rape. Watch out for and treat potatoes for blight. Catch up on the third Enable Conservation Tillage webinar and the weekly podcast

Winter Oilseed Rape

Crops have progressed well in the last few weeks and pod fill is now nearing completion. While the frosts in April prolonged flowering, they are unlikely to have had much of an effect on overall yield however this remains to be seen. By early July most crops should be ready for pre-harvest desiccation.

Since diquat is no longer available the only options to prepare crops ready for harvest are desiccation with glyphosate, swathing or natural senescence. By far the most popular method is desiccation with glyphosate as both of the other methods are quite risky. 

Guidelines for desiccation with glyphosate;

  • Sample the crop across the field and select the most representative areas. Select pods in the middle of the main raceme or on side branches, whichever is most representative. Pick 20 pods at random.
  • If seed colour change from green to brown is seen in at least two thirds of the seeds per pod in at least 15 of the pods picked, this is earliest correct stage for desiccation.
  • Repeat the procedure in other areas of the crop to check that the assessment is applicable to the entire field. Spray within 4 days, unless the weather is very cool, then the window can be extended to 7 days.
  • Use a high rate of Glyphosate when burning off OSR (e.g. Round-up Flex 3.0L/ha) and especially when targeting perennial weeds.
  • Use 200-250 L/ha of water per hectare to get good coverage of the crop.
  • A pod sealant (applied with the glyphosate) may be useful especially if harvest is delayed.
  • An interval of 14-21 days is necessary before combine harvesting.


There have been a few blight warnings issued this season so farm but reports of blight are very few. Most growers are using systemic fungicides e.g Infinito or Zorvec at this stage. Always have some cymoxanil on hand e.g. Option C50 in case there is an outbreak as these products have goo curative activity but can often be required at shorter intervals to try to dry up blight. In severe cases be prepared to apply every 3-4 days until the lesions are dry.

Alternaria or early blight is also being reported in some crops this year Vendetta or Amistar are the best products to control it but they work best preventatively.

Slug pellets have been applied to most crops at this stage, even though it is dry, slugs will still be active. Aim to have a full application of pellets on before the canopy closes, this will probably need to be topped up by the end of the month as the keeled slug only emerges above ground at the end of July.

ECT Webinar

The third of the Enable Conservation Tillage webinar series took place this week with reports form farmers Rob Coleman in Cork, Dill Shanahan in Waterford and Donie McGrath in Tipperary and discussed with how each of them are dealing with different grass weed issues on the farms.

The webinar is available on the Teagasc website here

Tillage Edge Podcast

On this week’s Tillage Edge Podcast Shay Phelan catches up with Teagasc advisors Michael McCarthy in Cork, Conor O’Callaghan in Dublin and Martin McCullough in Donegal to see how crops were looking in their respective areas and the prospects for the upcoming harvest. There were differences in the seasons in the areas with weather having significant effects on crop growth, disease pressure and subsequently crop potential. The lads also discussed the impact of the Straw Incorporation Measure (SIM) and the impact it had on the straw market and the prospects for grain.

Listen to the podcast here

Read more here from Teagasc on Cereal Crops 

The Teagasc Tillage Crop Specialists issue an article on a topic of interest to Tillage farmers every Thursday here on Teagasc Daily