The latest edition of Teagasc’s ‘Tillage Edge’ podcast features a review of the threat posed by Barley Yellow Dwarf Virus (BYDV) to recently emerged barley and wheat crops.
According to Teagasc’s Michael Hennessy, the acreage of winter crops sown out this autumn is well up on 2020. This is especially the case where barley and oilseed rape are concerned.
He said: “But a combination of early planting, in many cases, and the continuing warm weather is giving rise to a concern regarding the numbers of aphids and the risk of BYDV in crops this year.”
Threat from aphids
Hennessy was joined by Teagsc Oakpark-based entomologist Dr. Louse McNamara, who discussed the enhanced threat posed by aphids this year.
She explained that BYDV can affect any cereal crop or grass ley.
“The aphid vectors live in these crops. A severe BYDV infection can result in up to 80% losses within a cereal crop,” she explained.
“Previous Teagasc research has confirmed that losses in winter oats and winter wheat can total 2t/ha. Where winter barley is concerned, this figure can rise to 5t/ha.”
BYDV in regions
McNamara explained that different parts of the country are more exposed to BYDV infections than others. This assertion arose from trials carried out in counties Carlow and Cork during 2016 and 2019.
She continued: “Locations close to the coast tend to have less frost and milder winters. In turn, this means more aphids and more BYDV.”
According to McNamara, the milder the climate, the greater the chance that aphids will survive the winter.
Teagasc has a new suction tower network located around the country.
“These record the migratory aphids. We only have a couple of years’ data from these towers. However, we do know that the number of grain aphids in Carlow last summer was much higher than was the case in 2020,” McNamara said.
“And this trend is very much weather-related. But it will be very interesting to see how this translates into disease pressure this autumn.”
The Oakpark-based scientist went on to explain that BYDV-related problems can occur as a result of primary and secondary infection.
“A primary infection is caused by individual aphids initially moving into a cereal plants,” she said.
“Secondary infections are caused if the aphids get the opportunity to move around a crop.
“The milder the weather conditions, the greater the chance the aphids will have to spread disease.
“It only takes 15 minutes for an aphid to acquire the virus and a similar amount of time for the insect to start spreading BYDV,” McNamara concluded.