Thomas Lyons 
Late sown spring barley crops in Ireland are facing a high risk of being attacked by Barley Yellow Dwarf Virus (BYDV), according to a warning issued by Teagasc. Although some parts of the country have already drilled a proportion of crops about two weeks ago, growers in the north east have only recently been able to access their fields. Teagasc entomologist, Dr. Louise McNamara, has projected that aphid numbers will increase dramatically with the expected rise in air temperature. She stated that aphids will be more active and will multiply quicker as conditioner becomes milder. Dr. McNamara explained that every 170 degree days will see aphids doubling in number.
There are 25 species of aphids that can spread BYDV, and the three that give most cause for concern are the grain aphid, the bird cherry-oat aphid and the rose grain aphid. Each has different main hosts and will alternate hosts, depending on the weather. Dr. McNamara confirmed that every aphid is born with the next two generations alive inside of them. She said this means they have “the ability to reproduce in the field very quickly.”
Dr. McNamara also outlined that the threat of BYDV is very much temperature linked. She has indicated that the cooler the conditions, the less active that aphids will be. Reports have indicated that some winter cereal crops have already been quite heavily impacted by BYDV. This was a direct result of farmers not being able to get out into the fields last autumn. However, this is not the situation in the majority of cases.
The 2023 spring planting season in Ireland can be split into three broad categories: very early sown crops that were drilled in February, a very small proportion that was sown out during March, and the bulk of this year’s crop that has gone into the ground over recent days. Dr. McNamara has advised that growers should take extra precautions to protect their crops from BYDV.
Farmers are advised to monitor their crops and take action when necessary. Early detection and treatment are crucial to prevent the virus from spreading. Insecticides can be used to control aphids, but they should be used with caution as they can also harm beneficial insects. Dr. McNamara recommends using a threshold approach to determine when to spray. This involves monitoring aphid numbers and spraying only when they reach a certain level. This can help to reduce the risk of unnecessary insecticide use and minimize the impact on beneficial insects.
In summary, Teagasc has warned Irish farmers that late sown spring barley crops are at high risk of being attacked by BYDV. The warmer weather expected in the coming days will lead to a significant increase in aphid numbers. Aphids are born with the next two generations alive inside of them, which means they have the ability to reproduce in the field very quickly. There are 25 species of aphids that can spread BYDV, and the three that give most cause for concern are the grain aphid, the bird cherry-oat aphid and the rose grain aphid. Farmers are advised to monitor their crops and take action when necessary to prevent the virus from spreading. Insecticides can be used to control aphids, but they should be used with caution to minimize the impact on beneficial insects.
