Farm Ireland
Independent.ie

Sunday 22 October 2017

Spring barley at the right stage for herbicide

Pat Minnock

Pat Minnock

THE growth and development of crops has slowed over the last two weeks, but the rain was very welcome, even if it did make it difficult to get spraying done.

Most winter barley crops have passed growth stage 32 and nitrogen should be brought up to 160kg per hectare (180kg if extra yields can be proven).

The T1 fungicide should have been applied at this stage.

Crops are clean but there are significant levels of Barley Yellow Dwarf Virus (BYDV) evident, even where crops were sprayed with an aphicide a number of times in the autumn.

Is this an indication of aphicide resistance developing? The mild autumn has, no doubt, contributed to this problem. It is worth noting that last summer Rothamsted Research in Britain identified a pyrethroid resistance in the grain aphid (Sitobion avenae). The incidences of BYDV should be monitored carefully over the season so that remedial action might be considered for next season.

Spring cereals are well established, with most crops at or beyond growth stage 20. The main split of nitrogen should now be applied. Total nitrogen for spring wheat at index 1 should be brought up to 140kg/ha, barley to 135kg/ha and spring oats to 110kg/ha.

Again, there is an allowance for an extra 20kg if historic yields can justify it. But don't forget to allow for any organic fertiliser used.

Most spring barley crops are at the ideal stage for herbicide treatment. There are a large range of excellent products available.

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In good growing conditions and with small weed size, sulfonylurea (SU) product rates may be reduced by at least a third, depending on the weed spectrum present.

All the SU products have different strengths and weaknesses in terms of weed control and should preferably be tank mixed with other products (CMPP, HBN, Fluroxpyr, Foundation or Galaxy) to achieve better control and to help against weed resistance.

The addition of a low rate of CCC will help tillering. For crops under pressure or with low P indices, the addition of a liquid phosphate will be beneficial. All late sown spring barley crops should receive an aphicide for BYDV control.

The main split of nitrogen has generally been applied to winter wheat crops which are at or past growth stage 32.

The T1 fungicide has been delayed in a number of cases due to the inclement weather conditions. There are many options available for the T1 fungicide. While septoria levels are high, in many early sown crops it has not moved due to the weather conditions.

The new SDHI's such as Adexar, Aviator, or Boscalid containing fungicides may be the current flavour of the month. However, they are expensive. There is still a place for triazoles (at robust rates), particularly products containing high levels of prothioconazole. At €15/ac plus VAT, these can work out at half the price of the new SDHI's and for the poorer or more backward crops they might be a good option.

In eyespot situations the use of Cauldron, Proline or Venture extra should be considered, with Procloraz suitable in low risk situations. Include chlorothalonil in all T1's as an anti-resistance strategy. Also include a growth regulator (Terpal, Cerone or Modus) if not already applied.

Many winter oat crops are advanced and have suffered from chemical damage. At least some appear to be growing out of this. Products such as Tocata/Capalo (epoxiconazole, metrofenone and fenpropimorph) are considered to be very good T1 fungicides for oats.

The new oil seed crop Camelina is growing along nicely. There are up to 400 acres of the crop growing this season. Crops are located in Tipperary and in east Leinster. The growing season is very short and is expected to be about 100-110 growing days. Spring crops were sown in early March.

It is low input with little fertiliser and no fungicide required and so is relatively inexpensive to grow (€500 per hectare, €200/ac).

A maximum of 100kg of nitrogen is used with no P or K required, even on index 2 soils. Good soil conditions are required. The seed is finer than oil seed rape seed.

Weed control is generally pre-emerge with Butisan S. A yield of 2.5t/ha dried (1t/ac) is achievable and is valued at €800 per tonne dried (8pc moisture content and 4pc admixture).

This is a new tillage crop being trialled by members of the ITCA, and it has been included by the Department of Agriculture for the Single Farm Payment in 2012.

It is an excellent break crop and provides good potential returns.

Pat Minnock is a Carlow-based agricultural consultant and a member of the ACA and the ITCA. www.minnockagri.ie

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