Dual azole approach offers higher level of control than single azoles confirms Agrii agronomist

  Growers are being reminded about the importance of fusarium control at T3 to combat fusarium ear blight, a complex disease that can account for potential yield losses of up to 25% in winter wheat crops.

  Agrii agronomist Jazzmyn Jex confirms that F. graminearum, one of the 7 fungal species of fusarium posing a high risk to wheat growers, could be a more significant threat this year due to the hot, dry conditions prevalent in both April and May.

  Jazzmyn says” The risk of fusarium is always driven by climatic conditions, with F. graminearum, in particular, favouring warmer and drier conditions from sowing until around Growth Stage (GS)31, 1^st node. With much of the UK recently experiencing the sunniest April on record followed by similar hot, sunny conditions in May, this could increase the risk of F. graminearum with crops already under strong hydric stress in many areas. Although it's always difficult to predict whether fusarium is likely to be a problem, given conditions at flowering are the defining factor in its severity. Dull, wet and humid conditions will prolong flowering, keeping the florets open and allowing more time for the pathogen to enter the crop.

  “Whilst fusarium species are difficult to control, with even the best treatments and timings struggling to give full control, fusarium needs to be managed at T3 to maintain grain quality. Effective control of fusarium also reduces the risk of high levels of DON (Deoxynivalenol) and ZEAR (Zearalenone), harmful toxins that contaminate the wheat grain.

  “Good rotational management is important, paying specific attention to rotations where wheat follows maize and are at the highest risk from fusarium attack, given that F. graminearum develops well on maize trash. Although both variety choice and establishment can also have a positive impact on successful fusarium outcomes, ensuring that the T3 fungicide spray is timed to coincide with the start of flowering at GS61 and applying it no later than mid-flower, GS65, when the florets are open is most critical.

  “On product choice, combining 2 different triazoles such as bromuconazole + tebuconazole in azole-based products such as Sakura or Soleil offers superior activity on fusarium species and brown rust when compared to single azoles such as straight tebuconazole or prothioconazole. Spray coverage is also key, so consider water rates and nozzle choice. Use of an angled, flat fan nozzle can be very effective if conditions allow” concludes Jazzmyn.  

  Julian Lamont of Haxton Farm, a 728ha arable and grassland farm based 6 miles north of Stonehenge in Wiltshire, has worked with Jazzmyn and her brother, Agrii agronomist Todd Jex, for a number of years. Having used bromuconazole + tebuconazole in preference to single triazoles such as prothioconazole for more effective control of both rust and fusarium, he sees several benefits to a dual triazole approach.

  Julian adds” Whilst grain quality is always important, we grow feed wheat, so our key priority is high bushel weights. If we can keep fusarium out of the crop it helps us to achieve a better grain size, with fewer screenings.

  “I’ve used Sakura successfully for a number of years now. It’s flexible, effective on both rust and fusarium, and its rain fastness and ability to penetrate the crop quickly is reassuring if the weather is looking patchy at the point of application. I generally apply Sakura at a rate of 0.6l/ha during the critical flowering period between GS63 and GS65 to maximise its effectiveness.

 “There is a good argument that many growers, including myself on occasions, have become overly reliant on popular triazoles such as prothioconazole – a product that can potentially be used on every crop and in every situation. However, at both T0 and T3, when product options are more limited, I’d always advise stepping back to consider other effective azoles which may do the job equally well, if not better, to improve resistance management strategies and protect the chemistry we still have” he concludes.

  Ruth Stanley, the new Commercial Agro Manager for Sumitomo Chemical UK covering the UK and Ireland, supports Julian’s views on widening the use of other triazoles to improve overall resistance management and highlights trial work on the performance of the bromuconazole + tebuconazole co-formulated combination.    

  According to Ruth” Both ADAS and the AHDB have trialled Sakura in recent years with results showing that a dual azole approach of bromuconazole + tebuconazole offers higher control of fusarium species, including more effective control of key T3 diseases such as F. graminearum and F. culmorum than solo azoles. Sakura also helps reduce mycotoxins levels in the crop which, if not eradicated, can make crop marketing a challenge, particularly if growing for milling or lower grade human consumption.

  “Future control of fusarium and other complex diseases such as brown and yellow rust is an ongoing challenge and, due to the probability that tebuconazole could disappear from growers armoury in the future, I’m pleased to confirm that Sumitomo Chemical are already exploring a straight bromuconazole with the expectation of availability for use by the time tebuconazole is withdrawn.

  “On a personal note, it’s a very exciting time for me to join the company, given that we are well advanced with technical trials on 2 new actives we hope to bring to the market in the near future. Indiflin (Inpyrfluxam) is a new SDHI fungicide used at T1 or T2 for control of both yellow and brown rust. UK trials have gone extremely well, and Indiflin should be available to growers in the near future. Pavecto, our other new active, is a disruptive Qol aimed at control of Septoria. It has also impressed in recent trials and could be a potential game changer for UK growers when launched” concludes Ruth.