RAGT's Genserus wheats – the modern solution to BYDV control

Date:04-07-2023

Genserus varieties from RAGT are the first BYDV-resistant wheats to be marketed in Europe. They offer protection against the virus from the day the crop is planted to the day it is harvested, for less than the cost of buying and applying a pyrethroid spray.

The trait greatly simplifies crop management and delivers targeted control, removing the need to monitor and control aphid populations with foliar-applied insecticide sprays.

This is good news for the pocket, spray operators and, of course, the environment. Whether you agree with the sentiment or not, pressure is building on agriculture to ‘clean up its act’, and the environment is now a key constituent of agricultural policy.

A well-respected agronomist and a farmer with experience of growing BYDV-resistant wheats, both welcome the prospect of an insecticide-free autumn spraying programme on their wheats.

BYDV resistance – a ‘massively important’ breakthrough

Insecticides are currently the main method of controlling the spread of barley yellow dwarf virus in wheat, but hopefully that is about to change, says one well-known agronomist.

BYDV pressure may not be as high in TAG agronomist Jon Bellamy’s area as some of the coastal hot spots across southern England, but he is taking no chances with the potentially devastating disease.

BYDV-resistant and susceptible varieties under extreme pressure

The less favourable topography and climate of Oxfordshire and Northamptonshire, together with the move to later drilling to combat blackgrass,  reduces the risk of aphid migration into wheat crops but doesn’t remove it. Many crops will need one spray in a typical season.

Indeed, in a mild autumn/early winter almost any cereal-growing area in the UK can suffer damaging infections, and this is exacerbated in areas where early drilling remains the norm, where two or more sprays may be required in some years.

″Severe outbreaks of BYDV can result in large yield losses, but low-level damage can also leach profits,″ says Jon. ″With so much at stake, it is not surprising that we see an element of insurance spraying to control this virus.

″We are talking big money in terms of investment and there is a lot at risk. Getting hit by BYDV in the spring after spending thousands of pounds on crop establishment and inputs is disastrous.

″This autumn we were getting catches quite late, so it would have been easy to talk oneself into having to spray a second spray this autumn. Whether that would have been the right thing to do remains to be seen.″

Jon always discusses BYDV with his clients every year in some detail. ″Most are well informed, but some people have become a bit blasé about it.

″We’ve had neonicotinoid seed dressings for years that gave us good control, and more recently later drilling because of blackgrass has helped, and people have got away with it.

″This winter has probably been cold enough to help us out, and perhaps some growers have been quite lucky in that respect. The trouble with BYDV is you don’t know until it’s too late.″

There are plenty of apps and decision support systems available but these only indicate whether the season is high or low risk.

″They will all inform you when T-sum 170 is reached, when the second generation of aphids is likely to be present,″ says Jon.

″It is still up to the grower or their agronomists to check crops for aphids and decide whether to spray or not, it is really difficult and time consuming to inspect fields for aphids and be 100% confident there are none there, so we are back to square one.″

Genetics – the other way

While control of BYDV may appear fairly straightforward, agronomists hate using insecticides, says Jon. ″It’s not just us, no farmers want to use an insecticide unless they absolutely have to.

″The first point when giving advice as a BASIS qualified agronomists is to ask whether you need the spray in the first place, or can you do it some other way.

″BYDV resistance in wheat opens the door to another way. It is massively important, not only in terms of management but from an environmental point of view.″

He believes sprays are often applied unnecessarily, not just because they are used as insurance but because probably only 25% of the aphid population is carrying BYDV.

″Spraying crops when there is no need is a real waste of energy, as is making and transporting the plant protection products required for the job,″ says Jon.

″And it exposes beneficials and other non-target species to the insecticide, which no-one wants to do.″

Over-exposure of aphid vectors to pyrethroids, the main group of insecticides available to control the aphid vectors, also increases the likelihood of declining efficacy and eventual resistance, he believes. ″It is widespread in grain aphids, and there are indications of resistance in bird cherry-oat aphids in Ireland.″

The £45/ha recently made available under stewardship for keeping areas of the farm insecticide free fits well with BYDV-resistant varieties. ″I think this is good money and could be quite important,″ says Jon. ″Some growers might want to use BYDV-resistant varieties to help secure this payment, especially if end users get on board.″

Resistant varieties are a ″huge step forward″, Jon concludes. ″Everyone I speak in the industry is saying what a great trait to have coming along.

″I can’t wait until we have many more BYDV-resistant varieties. It will be such a help in managing our wheat crops, and so much more efficient too.″

Clean as a whistle - RGT Grouse is the latest Generus variety from RAGT

BYDV-resistant wheats find favour in Lincolnshire

Varietal resistance to barley yellow dwarf virus has already proved itself at Croft Marsh, Skegness, Lincolnshire, where Gavin Bowser manages 1000ha of winter and spring combinable cropping.

BYDV can be a problem on early drilled wheats, which are favoured on the farm’s silty clay loams despite potential blackgrass pressure.

Late-drilled wheats have been tried but were deemed too risky after two poor autumns in 2019 and particularly 2020, when a third of the planned winter wheat area was left undrilled.

The decision to revert to a 20 September start has been made easier by the successful introduction of spring barley and spring beans as effective alternatives to late drilling to suppress blackgrass.

″There’s no doubt that BYDV is more of a problem in early drilled wheats,″ says Gavin. ″But going round spraying insecticides is not what we want to be doing, or be seen to be doing – this sort of chemistry is frowned upon as it is, without making matters worse, and we are in danger of losing it, not only through regulation but because of resistance as well.

″We are very conscious of this and treat crops accordingly.″

Conventional varieties are monitored and sprayed with pyrethroid when conditions favour infection spread and aphids can be found in the crop. Most varieties had one application this year.

″I have a very good agronomist and I know we are getting this right, only spraying when we have to,″ says Gavin.

However, this takes time to manage and, while sprays are well timed, they are still environmentally damaging.

″Anyone who is not concerned about the environmental aspects is burying their head in the sand,″ he adds. ″Insecticides are under the spotlight for all sorts of reasons, not least because they are not target specific.

″We are moving into a direct-drilling system, and will introduce this across the whole farm in time. While this is mainly for economic reasons, it is also much more sustainable and, as part of that, we need to be looking after the whole ecosystem to maximise the benefits and produce healthy crops.″

Gavin believes growing resistant varieties fit perfectly with this vision. He is growing RGT Wolverine, Europe’s first commercial BYDV-resistant winter wheat, for the third season.

″Genetics are definitely the way forward and will make managing the disease a lot easier. We saved the cost of a spray, and it made for easier management – we didn’t have to monitor the crop for aphids at all during the autumn.

″The variety yielded as well or better than our other wheats. But, when we started with Wolverine, we knew it was the beginning of the next generation. It’s not the one that’s going to change the world, but it’s the beginning of a pipeline that will.″

Gavin is hoping to try RGT Grouse, the next variety in the Genserus (BYDV resistant) pipeline, a high-yielding hard feed wheat with improved agronomics that also features orange wheat blossom midge resistance.

It is highly suited to early sowings and features prostrate autumn and winter growth with high tillering capacity and retention.

″With our move to direct drilling we need varieties with plenty of vigour and it sounds like RGT Grouse has been bred for the early drilling slot,″ says Gavin.

″I’m looking forward to giving it a go, and to seeing what other BYDV-resistant varieties we can expect in the not-too-distant future.″