Apr. 18, 2019
Many growers may recognise they have a rhizoctonia problem only when symptomatic bare patches emerge in their crops, however the hidden effect of the disease already could have been significantly limiting yields for some time.
Image: Shows the response of barley to the new seed treatment fungicide EverGol® Energy applied at 130 mL/100 kg of seed to control rhizoctonia in the Katanning trial (centre), compared with Vibrance applied at 360 mL/100 kg of seed (left) and an untreated plot (right).
Bayer Customer Advisory Representative Craig White said root diseases were a widespread concern and rhizoctonia root rot, alongside root lesion nematodes, caused some of the biggest losses in the industry.
“Rhizoctonia can flourish in dry starts, and gravelly soils with low moisture can be really prone to it,’’ Craig said.
“Early on, the focus was on bare patches due to the disease, but it has been shown that it can also affect secondary roots, which are very important to take advantage of late rains and for grain filling.
“Growers may not observe visually they have an issue if the bare patches aren’t obvious, but it could be causing lower crop vigour and affecting plant uptake of available water and nutrients.
“Growers may note that they need to do something in following seasons when they see bare patches, but it could be affecting other areas of crop well before bare patches show up. The higher the disease infection in a paddock, the bigger the limitation on yield.’’
However, trials of a new broad-spectrum fungicidal seed treatment for winter cereals have shown improved disease control compared with existing standards.
The new product, EverGol Energy, which builds on the strong reputation of EverGol Prime from Bayer, combines the proven disease control strengths of penflufen with the systemic activity of prothioconazole and metalaxyl in a low dust formulation.
As a seed treatment, it offers control or suppression of a wide range of diseases including loose smut, rhizoctonia, pythium and crown rot (natural field infestation) in wheat, barley, oats and triticale; fusarium head blight and seed borne crown rot in wheat and barley; flag smut (seed and soil borne), common bunt and white grain disorder (seed borne) in wheat; and covered smut in barley. EverGol Energy also can be applied in-furrow for suppression of crown rot and pythium in wheat, barley, triticale and oats, allowing growers additional flexibility.
A trial north of Katanning conducted for Bayer by independent agricultural research company, TrialCo, last season compared the new seed treatment alongside an existing fungicide, Vibrance®, in barley on heavy clay soil.
A Predicta® B soil test confirmed the site was free of any background rhizoctonia, before it was inoculated with the disease to a level that resulted in uneven crop due to the disease.
The replicated seed treatment applications in the trial included EverGol Energy at 130 mL/100 kg of seed and 260 mL/100 kg of seed, compared with Vibrance at 360 mL/100 kg of seed and untreated plots. The barley seed was also treated with Gaucho® insecticide for protection of the seedling crop against aphids.
A further rhizoctonia treatment included a split application of EverGol Energy comprising a portion of the product applied to the seed and a portion applied in the planting furrow. At the time of publication, EverGol Energy is not registered for this use pattern, but an application to the APVMA has been made and approval is expected towards the end of 2019. Bayer recommends EverGol Energy always be used according to the most recently registered label. EverGol Energy is currently registered for in-furrow application for crown rot and pythium suppression at 300 mL/ha.
Craig said the crop response to the treatments was becoming clear by the tillering stage, with extra vigour and biomass in the seed treatment applications and with the split application of EverGol Energy.
Image: Shows the rhizoctonia seed treatment applied at 260 mL/100 kg of seed (right) and the strong barley response to a split application of EverGol Energy (left) comprising 130 mL/100 kg on seed and plus an in furrow application. An application to the APVMA has been made for this use pattern and approval is expected towards the end of 2019.
“The barley in the untreated plots varied from three-leaf to early tiller with lower vigour, whereas in the treated plots it was at tillering and was more even,’’ he said.
“We saw a crop response with the lower rate of EverGol Energy and the response at 260 mL/100 kg of seed was very good.
“People who viewed the site said it was an amazing result and there were really good comments on how even and solid the crop was where there were split applications of EverGol Energy on the seed and in-furrow.’’
“The in-furrow application of EverGol Energy showed that it helps its distribution through the profile. It would provide added flexibility for those growers who have the capacity for in-furrow treatments, as well as excellent smut protection.’’
After a dry start to the season, the site received good growing season rainfall before a dry spring.
Final yields confirmed the superior protection offered by EverGol Energy compared with existing standards. The lower EverGol Energy application rate of 130 mL/100kg achieved a yield of 5.44 t/ha, matching the 5.41 t/ha yield from the application of Vibrance at 360 mL/kg. The higher EverGol Energy application rate of 260 mL/100kg recorded a yield of 5.83 t/ha and the split application of 130 mL/100kg and 200 mL/ha in-furrow elevated yield to 6.24 t/ha. The untreated plots yielded 4.53 t/ha.
“EverGol Energy is a jump above the standards for rhizoctonia control. It is also fantastic for smut protection and demand for the product is already strong,’’ Craig said.
“It can help ease the impact of diseases and even out the growth across paddocks, effectively helping crops to better reach their potential.’’