Early risk factors point to high BYDV pressure
Recent rains onto warm soils could trigger a flush of weed and volunteer growth to create a green bridge for potential virus carrying aphids.
With many growers looking to drill this season’s crops earlier - to avoid a repeat of last autumn’s atrocious campaign - there is seriously increased risk of exposure to Barley yellow dwarf virus (BYDV) infection, warns Syngenta Technical Manager, Dr Max Newbert.
“Aphid numbers built up to unprecedented numbers earlier in the season, especially through periods of dry, settled weather,” he reported.
“Numbers of beneficial predators have responded accordingly, but it does mean we are working from a high base of potential pest pressure.”
Aphid monitoring services have picked up numbers of all the key BYDV infection vectors, including bird cherry aphid (below) and grain aphid (above). “Syngenta has insect traps out around the country this autumn to pinpoint migration timing.
“We will also be testing the aphids caught to identify the numbers carrying BYDV, which last season up to 42% of aphids carried BYDV.”
BYDV infection can result in stunted plants, with poor vigour and small heads - leading to reduced yields. Early sown crops, emerging when more aphids are present and with longer exposure to infection, are most susceptible to highest losses.
Dr Newbert advocates that can help growers to better time initial aphid treatments to prevent colonies establishing and creating infection foci in crops. “Armed with that knowledge, the BYDV Assist App will create a bespoke recommendation for individual fields to stop secondary spread.” he advised.
Based on temperatures and aphid reproduction rates, the App will assess risk of pest populations building up, as well as making recommendations for follow-up treatments where appropriate.
With the current incidence of insecticide resistance, Dr Newbert points out that growers and agronomists must attain the highest possible levels of control, to make best use of opportunities for effective treatment.
“To limit BYDV spread that means using Hallmark Zeon as the most effective pyrethroid available, at the full recommended rate of 50 ml per hectare, and with the optimum application techniques,” he recommended.
Sugar beet growers’ experience of virus yellows spread by aphids this season is a stark warning for cereal growers. “The risks from early cereal drilling, migration of large aphid populations and the trend to extended open autumn weather conditions all point to a high pressure season for BYDV.
“Growers need to look at every tool available to mitigate the risk and reduce the pressure,” he added.