Possible solutions to the most pressing agronomic challenges are being tested at Zantra’s three UK-wide trials sites, ahead of expected changes to the chemical armoury.
With the clock ticking on some fungicides and key pesticides already being lost, the company’s trials are looking at alternative methods of pest and disease control, as well as the effectiveness of any new chemistry in future spray programmes.
In addition, upcoming varieties are being tested alongside existing choices with the help of seed specialists Dennes, to get a better understanding of their responses to inputs and different management regimes.
As Chris Bean, Zantra’s technical director explains, there are a number of key issues that growers will have to get to grips with in the next twelve months, so any initial answers from this year’s work will be very helpful in finding the best way forward.
“Solutions are likely to come from various sources, so some of them will require a different approach and a new mindset,” he says.
He outlines two of the most urgent challenges as septoria and BYDV control, following the loss of the neonicotinoid seed treatments, fears about the future of the multi-site fungicide chlorothalonil and the ever-present resistance threat.
“We’ve seen septoria control on a knife-edge this season,” he says. “All of the varieties at our Kent trial site are dirtier than expected and none of the treated wheat plots are clean.”
While it has been a difficult season for spraying, with windy conditions affecting timings, it’s clear that some fungicide chemistry has been struggling to hold disease, he reports.
“We are all aware that curative activity has been lost and fungicide performance is slipping,” he says. “What we’ve also seen this year is that depending on where they are being grown, variety resistance ratings have given inconsistent results – with identical ratings looking very different when grown side-by-side.”
As a result, at Zantra’s Kent site, growers are being advised to drop every variety’s septoria score by one point. Further west at the Gloucestershire site, wheat varieties with septoria ratings below 6 are considered too risky to grow.
“In some areas, 2018 was the first really stern septoria test for new varieties. It’s important to understand how these varieties should be managed.
“There is some new chemistry coming along in the form of Inatreq (fenpixoxamid), which offers hope as it has a different target site to other chemistry and appears to be highly active against septoria. Hopefully it will be approved by 2020.”
In addition, a T0 spray timing trial is being done to understand how chlorothalonil can be replaced at this early timing, continues Mr Bean.
“Chlorothalonil is under the spotlight,” he says. “It’s very likely that there will be restrictions on the amount that can be applied in one season and on the timings. It looks as though its use in the T0 slot will disappear.”
While there are existing alternatives in the shape of folpet and mancozeb, Zantra is taking the opportunity to look at other materials, including a new multisite product already available on the Continent and a bio-elicitor.
“Bio-elicitors work by switching on the genes in the plant which resist disease,” explains Chris. “They seem to have an effect and could be part of the future.”
They may also have a place as a seed treatment, as could bacterial products and various biostimulants, which are also being put through their paces, he reveals.
“Crops drilled later into the autumn, in less favourable conditions, could benefit from these materials, especially if they help with tillering and give higher head counts. So we’re looking at their effectiveness, along with existing seed treatment products.”
With seed treatments in mind, this autumn will be the last year that growers will be able to use the Deter range of seed treatments for BYDV control, as the EU has extended the ban on their use to include non-flowering crops, he remarks.
“Growers are going to need to know how to react in autumn 2019, when these products are no longer available. In a mild autumn and winter, the aphids responsible for transmitting the virus will continue flying into crops, so disease levels may explode.”
Foliar pyrethroid sprays can be used for control, but resistance to them has already been confirmed in some of the aphid species that spread BYDV and they do have an effect on beneficials, he warns.
“One hope for the future is a new foliar applied aphicide from Corteva, Isoclast, which is going through the registration process. If it gets an autumn recommendation, it should provide around three weeks activity.”
That means the timing of any application will be very important, he stresses. “Being able to look at some of these development pesticides before they are available is very useful. It gives us a good foundation on which to base our advice and future recommendations.”
