Northern Ireland’s College of Agriculture, Food and Rural Enterprise (CAFRE) is advising growers to be mindful of the impact that Barley Yellow Dwarf Virus (BYDV) can have on newly established cereal crops.
Last autumn saw higher levels of disease infection than would normally be the case.
CAFRE crops specialist, Leigh McClean, explained:
“This was partially due to warm, dry, settled weather after sowing, which encouraged winged aphid migration.
“The biggest BYDV risk is from early sown cereals as they are exposed to virus transmitting aphids for longer.
“The best integrated pest management (IPM) practice is to avoid September sowing where practical. This is particularly so in high-risk, warmer, sheltered fields at lower altitudes or those areas that are close to the coast.”
BYDV
Recent Teagasc research has shown where the risk of BYDV infection is high, a single pyrethroid application at the two- to three-leaf stage is effective in controlling aphids and reducing the level of BYDV infection for October sown cereals.
A second spray gives no yield benefit. For high risk September sown cereals, a second spray may be justified to protect yield if mild settled conditions continue through the autumn.
Multiple pyrethroid applications should be avoided as they accelerate resistance in the aphid population, making BYDV control more difficult in future seasons.
McClean further explained: “Growers should take some reassurance that if conditions are too wet, cold or windy to spray following sowing, they are also not good for aphid migration.
“The consequent risk of BYDV transmission is lower.”
Winged aphid migration is monitored across Northern Ireland by the Agri-Food and Biosciences Institute (AFBI). Populations are posted weekly on that organisation’s website along with a BYDV risk forecast.
Weed control
Turning to weed control in winter cereals, McClean advises the application of residual herbicides before the crop or weeds emerge.
“Growers should prioritise winter oats and barley as active ingredients, particularly those effective on grass weeds are limited to a few products,” he said.
“Spring herbicide options are fewer with these crops than is the case with winter wheat. Winter crops should be checked until plants are past the vulnerable seedling stage.
“The highest risk follows rape or vegetable crops where slug numbers are high, seedbeds are cloddy, damp and seedling emergence is slow.”
CAFRE is also advising cereal growers to monitor new crops for slug damage.
If slug numbers exceed four per trap in cereals or one per trap in oilseed rape, then applying ferric phosphate slug pellets should be considered.
To gauge efficacy, growers should look for decreased feeding damage as slugs often die unseen underground with these pellets.