Tolerant winter barley varieties have been proven to reduce the transmission of barley yellow dwarf virus (BYDV).

This is according to Jack Perry, a final-year Walsh scholar PhD student with Teagasc.

While these tolerant varieties may reduce transmission, they can still display BYDV symptoms.

However, yield will not be affected by these symptoms when an insecticide has been applied.

Perry noted that farmers should be careful, as tolerant varieties may show a reduced yield if they are left unsprayed.

Perry said that tolerant varieties will react differently to the three different BYDV strains - MAV, PAV, and PAS.

From his sampling in the past two years, he has found that MAV is dominant in Ireland, whereas the main strain in mainland Europe is PAV.

This means that the new tolerance genes have been understudied across Europe for the MAV strain, which Teagasc is now trying to rectify.

While this work concerns tolerant varieties, Perry noted that new resistance genes are showing promise in field trials and Teagasc will continue to work on this over the next number of years.

New BYDV guidelines

Teagasc researcher Louise McNamara also revealed that BYDV guidelines will be updated this autumn with the newest information. While this new advice may not be perfect, she said that it should give farmers an idea about the BYDV risk level they are facing.

Grassland acts as a huge reservoir for BYDV, according to Teagasc’s Marta Niedzicka. She said that BYDV can be found in arable margins but at much smaller levels than grassland.

Plant viruses

Niedzicka has also studied other plant viruses and noted that identification of these viruses is key, especially because visual symptoms are often not enough and molecular tests are required. However, not all viruses currently have tests available to detect them.

Beet yellows virus (BYV) is one such example. There have been severe outbreaks across Europe since the ban on neonicotinoids.

Niedzicka has now created a molecular test for BYV which can quickly determine if it is present in a plant.

Niedzicka also detected soybean dwarf virus in Ireland for the first time. This can cause losses of between 40% and 80% in soybeans and may have the potential to affect other legume species.

While Niedzicka stressed that this is not a cause for concern, it can be very helpful in creating risk assessments for the potential introduction of new legumes into Ireland.