Thomas Lyons 
Spring barley farmers in Ireland have been advised by Teagasc that crops drilled in April are at higher risk of barley yellow dwarf virus (BYDV) and will require an aphicide at the three-to-four-leaf stage for optimum effect. Full-label rates should be used to get the best control, but growers should also monitor fields after spraying to assess for resistant aphids. Early March-sown spring barley crops will not require an aphicide.
Weed control in spring barley crops is also a management priority at the present time. Early applications, at the four-to-five-leaf stage, using reduced rates will save money. The best results will be obtained when the weed and crop are growing actively. Sulfonylurea, such as Ally Max or Cameo Max or Harmony Max, can be applied at half to two-thirds the recommended rate in tandem with Fluroxypyr (0.75L/ha) or Galaxy (0.75L/ha) or Pixxaro (0.375L/ha). Alternatively, Zypar (0.75-1.0L/ha) can be considered almost a one-can solution for most spring-germinating weeds.
Teagasc confirms that Pinoxaden (Axial Pro 0.6L/ha) or fenoxaprop (Foxtrot/Farmco Wild Oats) can be applied with certain herbicides on different crops to tackle wild oats in spring cereal crops. Growers should check each label for restrictions. Where wild oat sprays are applied separately, farmers should comply with the intervals to maximise the efficacy of the products.
The quality of water can affect the efficacy of herbicides, according to Teagasc. However, in the vast majority of cases, formulations are optimised to overcome most of these difficulties. But where water quality is suspected, then the addition of an adjuvant can help. Uneven application as a result of worn or blocked nozzles can result in poor weed control, especially if conditions are not ideal. Nozzle selection can also affect the eventual outcome. Generally, as standard, sprayers are fitted with a 025-04 flat fan nozzle. In most situations, these nozzles are robust enough to apply a herbicide in the correct droplet size to get good control. The calibration of the sprayer using these nozzles is vital to ensure the herbicide is applied at the correct water volume and spray quality.
