3 July 1999

Beet clean-up

Winning ways with cereal and beet herbicides are being demonstrated in Belgium, reportsGilly Johnson.

ITS ironic. Just as British beet growers start copying their Continental counterparts and are embracing the so-called FAR herbicide technique in increasing numbers, beet producers across the Channel change tack.

In Belgium, the FAR system has moved on. Another ingredient has been added to the original phenmedipham (F), activator (A) and residual (R) formula: clopyralid, or Dow Shield.

Its not a new ingredient by any means. In the UK and Belgium, clopyralid has been used to control creeping thistle and volunteer potatoes, but at robust doses, bolted on as an extra to part of the FAR sequence of little and often sprays, or to conventional herbicide programmes. This is a strategy used by growers with particular thistle or volunteer potato problems.

What is new is the use of clopyralid early on at repeat low doses, with the aim of controlling broad-leaved weeds such as black bindweed, fools parsley and fat hen. In Belgium, the evolution of the FAR technique is giving growers extra breathing space with what can be a strict programme in terms of timing.

The new system is called FARM, because the clopyralid is marketed under a formulation called Matrigon in Belgium; this product contains 100g/litre of clopyralid. It is also sold as Lontrel. A low rate of 0.25-0.5 litres/ha is added into the early sprays within the FAR programme. Beware making direct comparisons on rates – the UK version, Dow Shield, contains twice as much active per litre, with 200g/litre.

Jean Luc Tilkin farms 160ha (395 acres) near Liege with his daughter Sophie, on fertile loam which is 12m deep. He has tried the revised FAR technique, FARM, this season for the first time and is pleased with the result. Its saved him money – about £15/ha (£6/acre) as compared with his former programme, and kept the beet clean. Adding low doses of clopyralid has also given him more flexibility – its not as critical to spray the beet religiously once a week; a gap of 10 days or more doesnt cause problems.

This year the programme has worked well against a weed population that includes mayweed, cleavers, field pansy, annual mercury and fat hen. Grass weeds are a minor problem. Mr Tilkin has not used an pre-emergence product, or mechanical hoeing. The full system is given in the table.

The secret of success, according to Dow agronomist Dominique Lepiece, is to start early. "Only look at the weeds – not the beet. Start with clopyralid as soon as possible, even if all the beet is not through yet."

"Growers who are using the FARM technique without a pre-em treatment must have ploughed well, so that the soil structure is good enough to allow the sprayer to travel easily. The soil should be relatively clean with no perennial weed problems."

lUK growers will be unfamiliar with some of these Belgian products. Haloxyfop-R-methyl is a grass weed herbicide with similar action to Fusilade, and is sold as Gallant or Eloge. Metolachlor (Duelor) is a residual herbicide with useful activity against late germinating fat hen and polyganums. The phenmedipham-PMP (Betanal) product is slightly different from those sold in the UK, and is in an EC formulation with 160g/litre active.

New weapon for cleavers

BELGIAN growers are the first to sample new cleaver killer florasulam, launched by Dow AgroSciences as Primus this spring.

Primus has leapt onto the cereal herbicide scene with an 18% market share, according to Aime Van Rumst, from the companys Belgian office. This is no mean achievement in what is a crowded cleaver market.

Key attribute of this highly active, low dose molecule is early season cleaver control. This would pitch it against rival early products such as Eagle (amidosulfuron), Lotus (cinidon ethyl), and the carfentrazone-ethyl mixtures Platform S and Ally Express, rather than Starane (fluroxypyr) with its later application window. Belgian growers are allowed to apply Primus between four leaf and second node stage of the crop, and weed kill takes between five to eight weeks.

Other arguments in favour of florasulam are good compatibility with fungicides, blackgrass products, sulfonyl-urea herbicides and growth regulators, and excellent crop safety. This makes it ideal as a flexible partner in the T1 spray mix on cereals, suggests Mr Van Rumst.

As a bonus, florasulam will also control chickweed, mayweed, volunteer rape, charlock, runch and shepherds purse. Speedwells, field pansy, dead nettle, fumitory and fat hen are not controlled.

Belgian trials are focusing on rates and timing of the new molecule. As Primus, the formulation is 50g ai/litre.

Average dose in the first Belgian season is just 75ml/ha, which delivers 3.75g ai/ha. Full recommended rate in Belgium is 100ml/ha, which works out at about £20/ha.

In the UK, its expected that the full recommended rate for cleaver control will be higher at 150ml/ha, because of our tougher, winter-hardened cleavers which grow on through the British winters present a tougher target, says Dows Bill Taylor. "For the best cleaver control, well probably be recommending the full 150ml/ha rate, but small cleavers will be taken out by 100ml/ha and some other weeds at 50ml/ha."

A useful spring mix for the UK might be florasulam with a sulfonyl-urea such as tribenuron-methyl (Quantum). Other options to plug the weed control gaps might be mixtures with metsulfuron and thifensulfuron (Harmony M) or flupyrsulfuron-methyl and metsulfuron-methyl (Lexus XPE).

Not FAR, but FARM – a refinement of the

Continental beet herbicide programme

Mr Tilkins treatments in 1999:

30 March Crop drilled

No pre-em herbicide

SPRAY 1:

26 April beet at cotyledon stage, 90% emerged

phenmedipham-PMP (160g/litre) 1 litre/ha

ethofumesate (SC 500g formulation) 0.25 litres/ha

clopyralid (100g/litre formulation) 0.2 litres/ha

metamitron 1kg/ha

mineral oil 0.75 litres/ha

SPRAY 2:

5 May phenmedipham-PMP (160 g/litre) 1 litre/ha

ethofumesate (SC 500g formulation) 0.2 litres/ha

clopyralid (100g/litre formulation) 0.2 litres/ha

metamitron 0.5kg/ha

mineral oil 0.5 litres/ha

SPRAY 3:

14 May phenmedipham-PMP (160g/litre) 1 litre/ha

ethofumesate (SC 500g formulation) 0.2 litres/ha

clopyralid (100g/litre formulation) 0.2 litres/ha

mineral oil 0.5 litres/ha

haloxyfop-R-methyl (grass weed herbicide Gallant 2000; 108g/litre) 0.5 litres/ha

chloridazon (Pyramin in a flowable formulation at 480g/litre) 0.5 litres/ha

metolachlor (sold as Duelor EC with 960g/litre) 0.4 litres/ha

SPRAY 4:

20 May metolachlor (Duelor EC with 960g/litre) 1 litre/ha

SPRAY 5:

25 May lenacil (Venzar) at 0.5 litres/ha