New trials network aims to reveal true impact of BYDV on wheat

Jack Holgate, RAGT’s arable products manager, says the aim of the trials is to provide growers with much-needed information so they can make the right varietal choices to help manage the disease.

“Official Recommended List trials don’t include this sort of assessment at present,” says Jack. “As a result, the effects of BYDV on the relative performance of wheat varieties are never truly considered, so many growers are unaware of how the yield pecking order changes when the disease strikes.

“Indeed, the stated aim of the RL trials is that the husbandry should be appropriate to achieve the highest quality and yield and, if the trial is in jeopardy, effective control measures including insecticide must be applied to the whole trial.

“This means varieties that are bred specifically to resist the disease never get a chance to show their true potential. This is a concern, given that we are now reliant on pyrethroids that offer relatively short-lived control, coupled with increasing aphid resistance and milder autumns and winters that favour aphid development and spread.

“In addition, given the way agriculture is being directed through government incentives such as SFI, which currently offers a £45/ha payment for growing insecticide-free crops, it makes even more sense for there to be a no-insecticide protocol in official trials, but it seems unlikely that will happen in the foreseeable future.”

18-site trial

In light of this, RAGT took the decision to set up a 18-site trial matrix across the Midlands, South and West of England and Ireland for harvest 2024, using a range of popular commercial wheat varieties and some of the company’s pipeline BYDV-resistant Genserus varieties (see table).

RAGT is working with several partners including seed merchants, Eurofins, AICC, agronomy companies and growers to establish the trials network.

“These trials should provide a large data pool this coming harvest and beyond to provide growers with essential information regarding variety performance in the presence of BYDV,” says Jack.

“Some sites will be inoculated with BYDV-bearing aphids, others will be left to nature. None will receive insecticide.

“We want to demonstrate what can happen under very high BYDV pressure and how Genserus varieties can cope with that, reducing costs and greatly easing autumn management. We also want to see what happens under a range of natural conditions. Growers can then decide for themselves whether Genserus technology should play a part in their risk management strategy.”

High BYDV pressure

The trials will build on RAGT’s existing BYDV work, which has revealed the true potential of Genserus varieties compared with their conventional counterparts when subjected to high BYDV pressure, reflecting the resilience seen over more than two decades of commercial production in Australia.

Trials carried out at Ickleton, Cambridgeshire last season compared seven Genserus varieties against a range of popular and pipeline conventional varieties.

The trials received Recommended List-protocol fungicide and PGR treatments, but no aphicide at all. Plots were inoculated with four sets of BYDV-infected aphids at two-week intervals in the autumn and again in the spring.

The Genserus varieties significantly outyielded the conventional varieties. RGT Grouse, RAGT’s main commercial Genserus variety, was over 8% ahead of Champion and yielded almost 15% more than Skyscraper (see graph). Similar results were achieved in the two preceding years.

A trial carried out in county Cork by Goldcrop looking at natural BYDV infection only also clearly demonstrated the strength of the BYDV resistance (see graph). All plots received full fungicide and PGR programmes but no insecticide.

“Genserus varieties took the top three places, with RGT Grouse equal top at 106% of controls,” says Jack.

RAGT will provide updates from the new BYDV trials as appropriate at key points in the season and will deliver a full report on the results after harvest.