Management of BYDV in cereals
Barley yellow dwarf virus (BYDV) is a viral disease vectored by cereal aphids. BYDV can cause significant yield losses in wheat, oats and barley, especially in autumn sown crops. Symptoms of BYDV may not become evident until 3 weeks after infection and include stunting, yellowing or reddening of leaves.
Initial BYDV infection occurs when infected aphids fly into a newly emerging crop. These aphids reproduce, creating live offspring which can spread secondary BYDV infection within the crop. Cereals are most vulnerable to BYDV when infected as seedlings up to GS 31 (1st node visible on main stem).
Yield loss from BYDV can be reduced by using a seed treatment insecticide (e.g. Gaucho* or Poncho*) and foliar insecticides. Seed treatment will provide protection from BYDV for up to 6 weeks after planting, until the start of tillering (GS 21). After 6 weeks, plant growth will have diluted the concentration of the seed treatment and its effectiveness is therefore reduced.
If no seed treatment insecticide has been applied crop inspection should commence immediately after crop emergence, otherwise monitor crops from the start of tillering or 6 weeks after planting. If aphids are present, an approved foliar insecticide (such as Karate Zeon) needs to be applied as soon as possible to prevent the spread of BYDV.
Insecticide persistence is influenced by temperature and ultraviolet light, with insecticides having greater persistence in autumn sown crops, due to lower temperatures and lower UV levels than spring sown crops.
Recent FAR trial data has shown Karate Zeon provides longer lasting aphid control than some other foliar insecticides applied to autumn sown winter wheat (see table).
Mean persistence of insecticides applied in autumn sown winter wheat
Source: FAR Arable Update – Cereals, Issue 205 (Feb 2016)
Benefits of Karate Zeon for BYDV control
- Contains a powerful UV protectant for longer lasting aphid control.
- Fast knockdown, repellency and anti-feeding activity helps prevent the spread of BYDV.
- Convenient low use rate of just 20 to 40 ml/ha.
- Capsule Suspension (CS) formulation reduces odour and risk of skin sensitisation.
- Capsules adhere strongly to the plant when dry for reliable rainfastness.
- Active ingredient is effective at low temperatures.
- Excellent tank mix compatibility with herbicides, fungicides and plant growth regulators.
Beneficial insect populations are relatively low at the early growth stage of cereals, when the risk of BYDV infection is greatest. The use of Karate Zeon early in the season is therefore unlikely to have a significant impact on beneficial insect populations, while offering the longer lasting aphid control.
For more information click here to download the KARATE ZEON Technote.