Revystar approved for use in sugar beet this season
© GNP Sugar beet growers in the UK are set to benefit from a new SDHI-azole fungicide that promises extra firepower for managing the four key beet diseases: cercospora, powdery mildew, rust and ramularia.
Revystar, which is already widely used to tackle foliar diseases in cereal crops, is now approved for use in sugar beet.
See also: Colorado beetle outbreak confirmed in Kent potato field
Containing 100g/litre of mefentrifluconazole and 47.5g/lite of the SDHI fluxapyroxad, it comes as a welcome option for beet growers following the withdrawal of cyproconazole-containing fungicides, including the key beet product Escolta.
A maximum of two applications at a recommended spray rate of 1 litre/ha can be applied, with a 28-day minimum harvest interval.
Professor Mark Stevens, head of science at the British Beet Research Organisation (BBRO), welcomed the label extension and explained that treatment should be applied at the first sign of disease for optimum control.
“Apply at the start of foliar disease attack and before stem elongation, remembering that there is a 14-day interval between each spray application,” he said.
Greater yields and margin
Iain Ford, business development manager at BASF, explained that Revystar provided strong and long-lasting control of all key sugar beet diseases, which keeps crops greener for longer.
“The maintenance of green leaf area allows plants to photosynthesise for longer, put sugar into roots and improve yield and quality, with improved margin over fungicide cost benefits,” he said.
Data from seven independent trials tested over three years revealed that a two-spray programme of Revystar delivered the highest yield of 98.9t/ha with the greatest margin over fungicide cost of £229/ha, followed by the product Angle (azoxystrobin + difenoconazole) at 97.5t/ha and a margin of £224/ha.
Comparison of two-spray treatments |
|||
|
Two-spray treatment |
Rate (litres/ha) |
Yield (t/ha) |
Margin over fungicide cost (£/ha) |
|
Revystar (mefentrifluconazole + fluxapyroxad) |
1 |
98.9 |
229 |
|
Angle (azoxystrobin + difenoconazole) |
1 |
97.5 |
224 |
|
Escolta (cyproconazole + trifloxystrobin) Note: withdrawn from use and comparison only |
1 |
96.8 |
211 |
|
Caligula (fluopyram + prothioconazole) |
0.35 |
94.7 |
135 |
|
Untreated |
– |
86.9 |
– |
Rates and timings
He recommended a two-spray approach at the T1 and T2 timings, with the first spray at the end of July and the follow-up about three to four weeks later.
“When controlling cercospora, apply at a rate of 1 litre/ha for best control and persistence, while for rust, powdery mildew and ramularia a lower rate of 0.8 litres/ha is recommended.”
However, he noted that reducing the dose reduced longevity of control.
Disease update for the 2023 beet season from the BBRO
Professor Mark Stevens Head of science at the British Beet Research Organisation (BBRO), says there has been no reports of foliar disease in sugar beet crops this season, but warns growers to remain vigilant as conditions can quickly change over the coming weeks.
“Powdery mildew is usually the first to infect crops from mid-July onwards, whereas rusts which have been becoming more apparent over the last five years infect crops later from August-October, when conditions are cooler and damper,” he says.
The disease which is making industry particularly nervous is cercospora leaf spot which unlike powdery mildew and rust, has the potential to quickly evolve fungicide resistance traits.
This is why it’s important to bring new modes of action and new products to the market, bringing new strategies for growers and ultimately avoid resistance development.
Cercospora can rapidly defoliate the canopy and lead to yield losses of up to 40%, while powdery mildew can cut yield by 20-30%, rust between 10-14% and ramularia byup to 24%.
“Remember that sugar beet can potentially put on 40% of its yield from the 1 September onwards, so the most important thing growers can do is maintain a green beet canopy.
“The best way of doing that is good variety selection and timely application of fungicides,” he concludes.
