Welcome to the October edition of the Life Scientific Newsletter.
October is always a busy month for us with our range of oilseed rape fungicides (AURELIA and ORASO), cereal herbicide (RIBER), and our insecticide (LIFE SCIENTIFIC LAMBDA) for use against BYDV and Cabbage Stem Flea Beetle.
The September edition of our Newsletter focused on the benefits of using RIBER early in your cereal grass weed control programme.
This month, we will focus on BYDV
Barley Yellow Dwarf Virus in autumn cereals
Weather conditions this autumn have meant that aphids can be found in crops now, so the risk from Barley Yellow Dwarf Virus (BYDV) must be considered.
BYDV is the name for a complex of viruses transmitted by a number of cereal aphids including the grain aphid and the bird cherry aphid.
The virus can cause yield losses of up to 60% in winter wheat and 50% in winter barley. An aphid will carry the disease for its entire life once acquired. The virus is not passed to the aphid’s offspring so has to be ingested by feeding on infected plants. Warm dry conditions encourage aphid reproduction and movement in the crop, increasing the risk of greater infection. Crops are infected in the autumn, although symptoms do not tend to appear until the spring, at which point it is too late for control.
Initial infection comes from aphids entering the crop through migration or via the green bridge from grass or volunteers. Further infection then occurs when the second generation aphids move out from the initial infection point. Infected plants grow slowly and the youngest leaves will discolour. Later in the season plants are stunted and yellow patches appear throughout the field.
As warmer temperatures encourage movement and reproduction of the aphids, weather and sowing date can make a big difference to the risk to your crops, with early sown crops in mild autumns being most at risk of infection.
Chemical control options are limited, so applying an insecticide at the right time is important. Agronomists and growers should check the crop carefully for the presence of aphids. Some monitoring tools are also available which use accumulated temperature to predict when aphids are likely to be present, and a lot of work is being conducted to improve monitoring and forecasting systems.
Timing advice on the Teagasc website is based on sowing date, with comments that risk factors for autumn cereals include, “Early sown autumn crops and mild autumns (aphid migration period lengthened)”.
Life Scientific’s pyrethroid product LIFE SCIENTIFIC LAMBDA, containing 100g/L lambda-cyhalothrin, is approved for the control of aphid vectors of BYDV in winter and spring wheat, winter and spring barley, winter and spring oats, rye and triticale.
Application advice on the label is to apply a routine spray of 50 ml/ha LIFE SCIENTIFIC LAMBDA in 200 L/ha water during mid-late October to cereals sown in September in areas where BYDV is known to be present. If aphids are seen to be present in the crop before this date, spray immediately and note that further treatments may be required particularly in mild winters. ln later sown (from October onwards) cereals apply 50 ml/ha in 200 L/ha water when a BYDV risk is present. Application is worthwhile up to GS 32 of the cereal crop to reduce the risk of BYDV. Routine sprays are advised when the cereal crop follows a weedy stubble or grass ley due to the risk of direct aphid transfer to the crop.
See the approved LIFE SCIENTIFIC LAMBDA label for full use instructions and restrictions.
