Early March-sown spring barley crops will not require an aphicide. However, those drilled later in the month, and which emerge in April, will, according to Teagasc.
Moreover, April-drilled crops are at higher risk, especially in areas with a history of barley yellow dwarf virus (BYDV) or near the coast.
Crops at risk should receive an aphicide at the three- to four-leaf stage for optimum effect. Growers should use full-label rates to get best control, but they should also monitor fields after spraying to assess for resistant aphids.
Management of spring barley
Weed control in spring barley crops is also a management priority at the present time.
Early applications, i.e. 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.
The weather before spraying will influence how well the weed takes up the chemical. Ideally, growers should wait for two or three warm days before spraying.
Sulfonylurea, e.g., 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.
When it comes to tackling wild oats in spring cereal crops, Teagasc confirms that Pinoxaden (Axial Pro 0.6L/ha) or fenoxaprop (Foxtrot/Farmco Wild Oats) can be applied with certain herbicides on different 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.
Water quality
According to Teagasc, the quality of water can affect the efficacy of herbicides. 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.
Where spraying is concerned, uneven application as a result of worn or blocked nozzles can result in poor weed control.
This is especially the case 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.