Barclay Crop Protection

Pay close attention to beet weeds

Weed control in the sugar beet crop could prove challenging for the majority of growers, thanks to last year's tough weather and the winter cold snap, making a well-planned approach to weed control essential.

Weed control in the sugar beet crop could prove challenging for the majority of growers, thanks to last year's tough weather and the winter cold snap, making a well-planned approach to weed control essential.

Last year's high rainfall had significant effects on soil structure which, combined with cold seedbeds brought about by this winter's weather, will create the potential for patchy and uneven emergence of beet.

"And although the cold weather will inhibit the beet seedlings, it often does just the opposite for weed seeds, stimulating germination and ensuring a good weed flush," says Bryan Pickles, technical sales executive with Barclay Crop Protection.

"We could see some very severe weed infestations this season," he warns.

Formerly an independent agronomist and crop consultant in North Yorkshire, where fodder beet - to which the same advice applies - has now replaced much of the former beet crop since the closure of the York factory, Mr Pickles also points out that the cold weather and saturated ground following snow melt will inevitably delay drilling.  "Often growers can manipulate the drilling date to give the seedlings a head start on the majority of weeds, but I don't think we're going to be so fortunate this year, and we'll see more weed competition at an earlier beet growth stage.

"Weeds emerging with the crop have the most marked effect on yield," he notes.  "Fat-hen is able to emerge and grow to four true leaves within ten days.  Beet grows much more slowly and if the weeds are not controlled satisfactorily, it will never reach its yield potential."

Despite the gloomy outlook, Mr Pickles says that with the correct strategy and timings, growers should be able to sidestep these pitfalls and avoid any significant loss of yield as a result of weed competition.

Mr Pickles argues that a robust residual active ingredient must form the backbone of beet weed strategy.  "I've always advocated metamitron.  It's easy to apply and can be used throughout the programme, at any stage of crop growth, and works well with a number of tank-mix partners.  What's more, the season-long limit of 15kg/ha gives growers plenty of flexibility in how it's used."

For the first treatment, Mr Pickles recommends a pre-emergence treatment of Seismic (metamitron).  "For sandy and other light soils, stick with 2kg/ha but on mineral soils this can be increased to 3kg/ha.  This good residual base has strong activity against a range of weeds including chickweed, fat-hen, knotgrass, mayweed, marigold and poppy."

With the potential for patchy crops post-emergence, he advises growers plump for a mix that works at all three crop stages - pre-em, peri-em and post-em.  "For example, 30g Debut (triflusulfuron-methyl), 1l Betanal Flow (phenmedipham) and 0.5kg Seismic, or perhaps substitute the Betanal for 0.5l oil.  Although it's a universal mix, it's also very crop-safe.  Notice again we're still building up the residual element, but the addition of Debut gives immediate contact activity to help with rapidly emerging cleavers, speedwell and shepherd's purse."

Most growers should aim for a three spray programme, he says, so get the third treatment right.  "Keeper (ethofumesate) is sometimes regarded as a 'fire-brigade' treatment, to be used only when control has really failed.  Actually it's ideal as a last-treatment partner and should be viewed as an integral part of any programme, active on annual meadow-grass, black bindweed, larger fat-hen, redshank and common fumitory among others."

Depending on weed profiles at the time of the third spray, Mr Pickles advises using between 0.5-0.7l of Keeper in a mix with between 1-1.5kg of Seismic.  "Some lesser infestations could be dealt with by the lower rate of Keeper but adding oil," he notes.

"I can't stress highly enough how important it is to keep up the residual element through the early stages of the crop.  You only had to look at some of the filthy beet crops about last year to see that many growers had not paid enough attention to incorporating a residual herbicide in the programme."