FARbetter thing?
FARbetter thing?
THE so-called FAR technique of weed control for sugar beet received a resounding thumbs-up from results of a BBRO-funded trial conducted at Morley Research Centre last summer.
But principal agronomist Martin Lainsbury stresses it is not the right approach for all. On heavy soils or distant fields including a pre-emergence Pyramin (chloridazon) application buys peace of mind for little loss of margin.
"That is worth knowing if you have a beet field 20 miles away and you dont want to be trailing down there every week."
Top performer on the sandy-clay loam at Morley was a mix of 0.75 litres/ha phenmedipham, 0.5 litres/ha ethofumasate and 0.5 litres/ha metamitron, applied four times, with esterified vegetable oil Toil added at 0.5 litres/ha for all bar the first application.
That mix costs £83/ha, including application costs, and produced an adjusted yield of 85.5t/ha, giving a margin over herbicide cost of £1814/ha.
Close on its heels were other FAR regimes. Leaving out the oil reduced the margin by £12/ha, and a mix using the Flo formulations of phenmidipham and ethofumasate without oil was £5/ha less than.
"Note the sugar beet where the Flo mix was used had better early vigour," adds Mr Lainsbury.
Substituting the metamitron with the cheaper residual Takron (chloridazon) at 0.5 litres/ha dropped the cost of the four spray FAR programme to just £60/ha without oil, and delivered a margin of £1805/ha.
That was just ahead of the conventional programme of pre-emergence Pyramin (chloridazon) at 1.7kg/ha followed by two mixes of 1kg/ha Goltix (metamitron) and 1.7kg/ha phenmedipham plus Toil at 1 litre/ha.
More costly formulations of products, such as Betanal Compact or Progress (desmedipham + phenmedipham or desmedipham + phenmedipham + ethofumasate) reduced margins by about £30/ha, but Mr Lainsbury acknowledges that weed control conditions were favourable last year.
"When the weeds are lush there is no need for these expensive formulations." In a cold, dry spring things can be very different, he adds.
• This trial was repeated at Rocklands, Norfolk, on a sandy soil, and at Otley, Suffolk, on a heavy clay loam. Results are not yet available due to late harvesting, but will follow soon, says Mr Lainsbury.
FAR
FAR stands for phenmedipham, activator and residual and is the term used for the little and often approach of sugar beet weed control pioneered by Mike May in the 1990s. Weeds are sprayed at the first sign of emergence when they are just pin-heads poking through the seed-bed.
Best margins at Morley
Programme A B C D
Early crop vigour (max 10) 7.8 8.1 8.4 8.9
Late crop vigour (max 10) 8.8 9.5 10 9.0
Population (000/ha) 84.3 85.4 85.8 83.4
Yield (adj t/ha) 84.6 84.3 85.5 83.1
Margin (£/ha) 1803 1802 1814 1805
Programme A 1.7kg/ha pre-emergence Pyramin (chloridazon) followed by 2x (1.0kg/ha Goltix + 1.7kg/ha phenmedipham + 1.0 litre/ha Toil).
Programme B 4x(0.75kg/ha phenmedipham + 0.5 litres/ha ethofumasate + 0.5kg/ha Goltix)
Programme C As for B but plus Toil for last three applications
Programme D 4x(0.75kg/ha phenmedipham + 0.5 litres/ha ethofumasate + 0.5kg/ha Takron)