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Fungicide performance in wheat, barley and OSR for 2021
Arable Fungicide performance and disease management in wheat, barley and OSR
At the Agronomists Conference 2021, Jonathan Blake, technical director of crop protection at ADAS, ran through the results of the 2021 fungicide trials conducted primarily by AHDB and ADAS with assistance from the wider fungicide working group. Rachel Hicks reports.
Mr Blake began by explaining that the AHDB Appropriate Dose Network was started around 27 years ago, and has been championing independent information on fungicides, looking at both e cacy as well as appropriate dose. The team has been testing various products at sites across the UK, located in the higher disease risk parts of the country. The products have been tested over a range of di erent spray timings, to give relevant protectant and curative data.
Wheat and barley
Table 1 shows the various agro-chemicals and their modes of action in wheat and barley that AHDB tested in 2021, and Mr Blake drew attention to two relatively unknown names on there, including Myresa (mefentri uconazole), the new azole which BASF recently launched, commonly known as Revysol (also available as a co-form with uxapyroxad in Revystar XE). The other he mentioned is Peqtiga (fenpicoxamid), which is also known as Inatreq – one of the active ingredients in Univoq, the new QII fungicide launched by Corteva in spring 2021. He pointed out that both Myresa and Peqtega are registered as solo products, but it’s not advised to use them that way, and commercially they are only available in a twin pack with a partner product, to be used with other modes of action.
See Graph 1 for a summary of their e cacy as a protectant at various dose rates. In the graph on the right hand side, it shows the products with a single active ingredient, while on the left hand side it’s the mixes. The data compares quarter, half, full dose, up to double rate. Arizona was tested at a single 100% dose for comparison.
Both of the mixes performed very well, so it is hard to separate them based on that data.
Testing the same products in terms of their curative ability, everything tended to perform less well. Mr Blake warned you should be careful when interpreting curative data though, as there are often numerous infection events that will have occurred prior to leaves being sprayed, and on many occasions, they may have a level of septoria that’s already beyond control. So, in terms of curative data, it’s not an absolute value – more just a measure of how products compare.
In terms of yellow rust trials, Elatus Plus and Imtrex provided the best control among the single actives at lower dose rates, while Elatus Era performed best in the mixes, which suggests it would have a role to play in geographical areas with a high rust problem. Mr Blake also suggested that yellow rust control is just as much about timing as it is about the speci c products used.
In the 2021 trial, Elatus Plus and Myresa were most e ective on brown rust and Proline the least, while in the mixes, Revystar XE was slightly stronger than Univoq, although both were e ective.
There’s a new addition to the barley toolbox, with Asca Xpro being newly registered in April/May 2021 for use in barley. It has a di erent full label rate for barley, at 1.2-litre/ha, and a total dose per crop of the same 1.2-litre/ha rate.
In terms of rhyncosporium, as a protectant Imtrex out performed the rest, followed by Proline, Revystar XE and then Ascra Xpro. However, as an eradicant, Ascra Xpro performed best, although Revystar and Imtrex weren’t far behind and Proline brought up the rear.
Net blotch and ramularia 5 were also tested against, with prothioconazole and uxapyroxad both being e ective at controlling net blotch, while mefentri uconazole (in Revystar) added good e cacy against ramularia. The SDHIs uopyram and bixafen (in Ascra Xpro) added useful activity on net blotch.
Table 1: Wheat and barley – registered products
Product Active (s) Mode of Action
Arizona* folpet Multi-site
Proline prothioconazole DMI (azole)
Myresa mefentri uconazole (revysol) Imtrex uxapyroxad Elatus Plus benzovindi upyr (solatenol) DMI (azole) SDHI SDHI
Comet pyraclostrobin
Qol (strobilurin) Peqtiga fenpicoxamid QII Ascra Xpro bixafen + uopyram + prothioconazole SDHI + SDHI + DMI Elatus Era benzovindi upyr + prothioconazole SDHI + DMI Revystar XE mefentri uconazole + uxapyroxad SDHI + DMI Univoq fenpicoxamid + prothioconazole QII + DMI
Barley only
Siltra bixafen + prothioconazole SDHI + DMI Kayak cyprodinil Anilinone-pyrimidine
*Arizona tested at 100% dose only. Table 2: Oilseed rape products
Fungicide performance in OSR
Architect and Shepherd have only just been registered for use in OSR – see Table 2 for a full list of OSR products tested. Shepherd (boscalid + pyraclostrobin) has a full label dose of 0.8-litres/ha, with the same total dose per crop. Architect (mepiquat chloride + prohexadione calcium + pyraclostrobin) has a full label dose of 2-litres/ha, with a total dose per crop of 4-litres/ha. In terms of di erences between products, for phoma stem canker, they are quite small. OSR crops are quite tolerant of canker, so there is little bene t from applying more than 50% of full label rate as part of a two-spray programme, with an average yield response of only around 0.3t/ha. For light leaf spot, azoles and non-azoles provided a similar level of disease control and yield, but the use of di erent modes of action (azoles/non-azoles in sequence or in mixture) is vital for resistance management going forward. FG Graph 1: 2021 Overtrials – Septoria Protectant (6 trials) Use Imtrex and Myresa only in mixtures with at least one fungicide with an alternate mode of action that has e cacy against the target disease 25 25 20 20 Disease %15 10 Disease % 15 10 5 0 0 0% 50% 100% 150% 200% 0% 50% 100% 150% 200% Percentage of full label rate Percentage of full label rate
Product Active (s)
Proline prothioconazole Priori Gold* azoxystrobin + difenoconazole Aviator bixafen + prothioconazole Filan* boscalid Architect mepiquat chloride, prohexadione calcium + pyraclostrobin Shepherd boscalid + pyraclostrobin Plover difenoconazole Amistar azoxystrobin Pictor dimoxystrobin + boscalid *No label recommendation for light leaf spot control but may be applied at the appropriate time, for the control of other diseases. Myresa Revystar XE Proline 275 Univoq Imtrex Arizona Arizona
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