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Tillage Update 20th May 2021

Mark Plunkett, Soil & Plant Nutrition Specialist reports on tillage crops and how they are developing in the southeast. He notes that many Winter Wheat Crops are at or near Flag Emergence. Mark comments on spring cereal crops and discusses Spring Beans and weed control in potatoes here also

Winter Wheat Crops at Flag Emergence

To date May has been an unsettled month with temperatures still below normal for this time of year and very heavy localised showers of rain.  This has made field operations difficult as many crops now require key inputs from timely weed and disease control.

In the Fields Crop Update

Winter wheat crops have developed well over the recent weeks despite the wet and cold weather conditions.  Crops have good colour and recent rains have help with plant N uptake.  Where not already done apply remaining 25% of total N application by GS 39.  Many crops are approaching or at Flag Leaf (GS39) emergence.  This is a key timing for controlling yield robbing diseases such as septoria & rusts. Crops range from flag leaf peeping to flag leaves fully emerged.  Crops that I visited had relatively low levels of septoria present –top four leaves clean. Recent wet weather conditions will provide ideal conditions for the development and spread of the disease over the coming weeks. Therefore, select suitable fungicides to protect crops. There is still opportunity in some crops to apply a PGR such as Terpal to further reduce lodging risk in crops.

Figure 1:- Winter wheat at flag leaf fully emerged and low levels of septoria present.

Winter barley crops are developing at a slower pace compared to previous years.  Crops range from ears fully emerged to crops at flag leaf stage.  Many crops have received their final fungicides with later sown crops now approaching the ideal timing – Awns peeping / paint brush stage (GS 49).  Later sown crops have relatively low levels of disease, however with current wet weather conditions and with weather forecast remaining unsettled, select a suitable fungicide to protect crops during grain fill.  The recent rains have again helped with the uptake of nitrogen as crops now have good colour.

Figure 2:- Late sown (November) winter barley approaching awns peeping.

Spring cereal crops range from early tillering to crops approaching 1st node.  Again recent weather has brought welcomed rain but unsettled conditions have made field conditions difficult for carrying out field operations such as weed control.  Many crops are showing signs of nutrient deficiencies such as Manganese and Magnesium.  Where deficiency symptoms are present include a suitable product to treat suspected nutrient deficiency.  To date disease levels reported are low but with current weather conditions and taking variety disease ratings  into account treated crops at recommended timings to prevent the spread of yield robbing diseases such as net blotch and rhyncosporium.

Updates on: Final crop fungicides and tips on efficient field spraying operations from this week’s podcast links below

In the video below Ciaran Collins, Crops Specialist describes the ideal timing for the final fungicide in barley 

Hear A Cork farmers solution to reducing spray drift below

Spring Beans like other crops to date have developed slower over the last number of weeks due to cooler weather conditions.  Crops visited had weevil damage present and may require treatment.  I also visited a crop of direct drilled spring beans and the crop had significant levels of slug damage.  Recent wet weather will have created favourable conditions for slug activity and direct drilled crops may now require treatment. Where grass weeds are present treat crops with suitable herbicide.

Figure 3:- Slug grazing on a crop of spring beans

Weed Control in Potatoes

Weed Control will be required in most crops in the coming weeks. Good pre-emergence programmes will give best control of weed but product should be field and weed specific. Mixtures of metribuzin products e.g. Shotput plus a partner product e.g Defy, Emerger etc. will give good broad spectrum control but be aware of label recommendations in terms of varieties or levels of crop emergence.

Ideally Shotput and other residual herbicides should be applied when the soil is damp for the best effect, so where possible wait until we get some rain before applying even if this means delaying until some plants are starting to emerge but again check label directions as to what level of crop emergence for different the varieties is advised with each product.

Glyphosate is being used more commonly pre-emergence in the last few years since diquat has disappeared but this needs to be done very carefully, crops should not be within 5 days of emergence when applying otherwise there is a significant risk of crop damage. Glyphosate will give good control of the weeds that are present at the time of application but it will give no residual control, in dry conditions this may mean a two application strategy of glyphosate application first followed 5-7 days later with a residual mixture.

For a full list of products and rates check out the May edition of our Potato Newsletter at https://www.teagasc.ie/media/website/crops/crops/potatoes/Potato-Newsletter-May-2021.pdf

For more Agronomy information check out https://www.teagasc.ie/tillagemonth/

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