Put triazoles to maximum use

19 July 2002

Ways to raise beet yields

Will you use a summer

fungicide to boost beet

yield this season? One

Norfolk grower reckons it

is a key part of growing

more beet on fewer acres.

We take a closer look

MAINTAINING a green leaf canopy for as long as possible is the key to achieving the best possible sugar beet results, says a Norfolk grower who raised output by 8% last year, despite the most challenging of seasons.

Drilling sugar beet earlier and making best use of fungicides to preserve green leaf cover later into the autumn is helping Geoff Hipperson, of Malrose Farm, Shouldham, towards his goal of meeting quota from fewer acres.

Appalling spring conditions, which delayed drilling by a month, and early sugar beet lifting to coincide with the British Sugar Beet Demonstration, which Mr Hipperson hosted last year, meant the odds were stacked against him.

But despite a short growing season he achieved an adjusted yield of 55.34t/ha on his medium loam over chalk soils without irrigation, exceeding his previous 10-year average by 8%.

Mr Hipperson puts that down to a range of management issues, including timely application of summer fungicides to keep leaf cover clean and green for longer. Seed treatments to protect crops against soil pests and aid germination, new bolting-resistant and more vigorous varieties, and improved cultivation and drilling techniques also played their part.

Currently Mr Hipperson aims to grow 50t/ha of sugar beet to fulfil A + B quota, plus 10% extra as a safeguard. "Our aim is to meet the sugar beet contract off less acres, and therefore to produce as much green top as we can to maximise sunlight utilisation."

Manganese was added to the second post emergence spray, plus boron and magnesium at full crop canopy. "Not everyone is doing this as standard," he says. "But our crop was backward last year and as we were hosting the beet demo we were trying everything to catch up.

"We applied Punch C at 0.625 litres/ha at the end of July to control mildew, rusts and ramularia, as well as to keep the green leaf growing longer. The difference between untreated and treated was noticeable within a week of application."

Sugar beet lifting started early, which meant he could not realise the full yield potential. But this year Mr Hipperson intends to treat up to two-thirds of the sugar beet with Punch C in an attempt to repeat last years result.

"If we find that the extra greening effect does result in higher adjusted yields then applying Punch C would become a routine management decision."

Despite a difficult season last year beet yields rose 8%, says Norfolk grower Geoff Hipperson. Foliar fungicides played their part, preserving productive leaf life.

&#8226 8% yield rise in 2001.

&#8226 Aim to hit quota from less area.

&#8226 Early drill and late leaf cover vital for top yield.

&#8226 Late July fungicides key.

Interval caution

Dont lose sight of harvest interval when choosing your beet fungicide, warns Agrovistas Neal Boughton.

"With a harvest interval of just 14 days, as opposed to seven weeks for carbendazim + flusilazole (Punch C), Alto (cyproconazole) offers a distinct advantage for those who arent sure when they are going to be lifting."

Trials last year showed crops treated with a sequence of half-rate Punch C followed by half-rate Alto scored a "remarkable" 9.7 on a greenness scale of one to 10, says Morley Research Centres Martin Lainsbury.

"In other words, they had leaves that were still perfectly healthy and still converting sunlight into sugar." Measurements were taken on Nov 20 when the crop would be expected to be at an advanced stage of senescence.

Alto was chosen as the second spray since it tends to achieve better control of rust, which comes into the crop later, says Mr Lainsbury.

That could be of particular value to growers using rhizomania-tolerant varieties, which are particularly rust-susceptible, with disease resistance ratings of only 1 or 2, points out Mr Boughton.

NIABs Simon Kerr confirms that poor resistance to rust appears to be a genetic weakness strongly associated with both current and future candidate rhizo-tolerant varieties.

Put triazoles to maximum use

WITH mildew and brown rust expected to hit crops hard this season, growers need to apply triazoles at the first sign of disease to maximise gross margin, says Peter Riley of Morley Agricultural Consultants.

Brooms Barn trials across six sites over three years comparing Punch C, Alto and straight sulphur show an average yield response of around 15%. About two-thirds of that stems from mildew, brown rust and ramularia control, estimates Mr Riley, the remaining 40% coming from longer green leaf retention.

"Punch C gave the largest increase, boosting adjusted yields by 4t/ha, compared with 3.3t/ha with Alto and 2.9t/ha with sulphur," he says.

"In an average 60t/ha crop that equates to an extra 7.5t/ha. Punch C and Alto were far superior to sulphur in terms of yield response and level of mildew, brown rust and ramularia control.

"The beneficial effect of adding a triazole to increase greening alone means we recommend our growers apply one as a routine application at the first sign of disease or from around Aug 1." &#42

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