Genserus BYDV resistance – a must-have trait in winter wheat, say trials partners

Bartholomews Agri-Food

Chichester

Across the wide geographic range in which Bartholomews operates, a high proportion of customers are in a high-risk area for BYDV, says arable technical director Andrew Stilwell.

“We have farmers on the low-lying coastal areas and in the sheltered valleys further north. We try to drill later in these areas, as this helps with BYDV and blackgrass control, and there is a definite desire among my own farmer clients to eliminate insecticide use on their crops.

“It’s nothing to do with economics – they just don’t like using them. Most now only spray once, with tau-fluvalinate, which does have a degree of persistence and has the best profile in terms of effects on beneficials. After that they take their chances.”

However, last season and in 2015, the area suffered some pretty horrific crop damage from BYDV, he adds. “And in some years crops could suffer from a low level of infection that may not be noticeable, but which can still reduce yield by a couple of percent.”

He believes his growers will welcome BYDV resistance with open arms. “This is quite a new concept for most people, but as it develops with new varieties and into quality wheats, which are important in our area, I think resistance will start capturing the imagination.

“The main attraction is security and peace of mind during the autumn establishment.. You are able to put your wheat crop into the ground, safe in the knowledge that BYDV is not going to be an issue.”

Bartholomews is managing four large trial sites in conjunction with RAGT in East  Sussex, Hampshire and Wiltshire, growing a range of Genserus (BYDV-resistant) varieties alongside the main Recommended List varieties to assess their performance under natural BYDV pressure in the field.

“We have sited them the trials in aphid-prone areas such as sheltered valleys and near hedges to encourage natural background levels,” Andrew explains.

“This should give a much better idea of how these varieties perform in practice, and illustrate both positive and negative traits that we can take into consideration when assessing where and when to use them.

“We have a potential high-quality breadmaking wheat named RGT Goldfinch in the trials which could really grab our interest, and we also grow feed varieties in the west part of our territory, so higher yielding characteristics will be important there.

“RGT Grouse started off slowly start and went through the winter very prostrate, which is the type of growth habit we’d expect from a variety that is perfectly suited to early sowing.

“When spring came and soils warmed and it received some fertiliser, it’s shown some tremendous recovery and spring vigour. Host farmers have commented on its growth pattern too, and it could be an attractive characteristic we could use going forward.

“We will be looking to make a conscious move towards commercial acreages of Genserus varieties to meet the changing mindset among farmers and to take advantage of the SFI option for land managed without insecticides.

“It makes perfect sense to have a variety that doesn’t need that input and marry the two together.”

Goldcrop

Co Cork

John Dunne, cereal variety manager at Goldcrop, believes BYDV resistance will be a must-have for growers in the near future as the trait becomes embedded in varieties that suit Ireland’s wet climate.

“Given our milder weather BYDV is a perennial risk across Ireland, and particularly in the south,” says John.

“Aphid levels have generally been low this year, but I’ve some nasty looking BYDV in winter barley just a couple of fields away from where I carry out my aphid counts, so it just shows the risk is there all the time.

“A bad outbreak in an unsprayed crop can cut yield by 10%, and there are likely to be hidden losses every year from sub-clinical infection.”

Most wheat is sown in Ireland around mid October. These crops are usually sprayed once with aphicide; research shows that is generally adequate and the weather often precludes a further application.

BYDV infection can occur after a calm week in January or February. “Yellowing can be quite transient in wheat, sometimes occurring in the second leaf upwards and then disappearing,” says John.

“When the ear is out you really see what’s hit the crop – the ear is darker and slimmer and the grains are small. You can get quite significant yield losses even from a late infection like that.

“That’s why I would say the Genserus trait is a great thing to have. It’s mitigating a risk. With autumns more frequently wet it’s harder to apply aphicides – if you don’t get it on you leave the crop quite wide open.”

John also points out that there are no new insecticides coming out and the availability of chemistry will probably reduce. In addition, all aphicides used have an effect on beneficials to some extent. They also break down fairly rapidly, particularly in sunny weather. “They are definitely not the silver bullet,” he says.

Agriculture has become a high cost/high stakes practice, so the economic argument for BYDV resistance in wheat is a sound one, John believes.

“Generally speaking, we’re all in the high input-high output model and you want to take as much risk out as you can. It would be terrible to spend all your money on fertiliser and fungicide to have it undermined by something that could be controlled genetically. So there is a very strong economic argument for it.”

Goldcrop is managing the RAGT trial in Ireland, which was drilled on 4 October. “Crops are looking a bit leggy given the early start, and have received no insecticide,” says John.

“Whether we get BYDV infection remains to be seen. Septoria is a big risk in earlier sown crops – it is very virulent in Ireland as a consequence of our excellent control over the past few decades; it has evolved to become very virulent.

“It will be interesting to see how current varieties cope. RGT Grouse in my plots last year and others in the pipeline appear to be going in the right direction and I like the look of them. Better disease resistance is coming through, and that will really make a big difference in this part of the world to the uptake of these varieties.”

See more about the BYDV trials here.