Flexible contact herbicide o ers a clean start in potato crops

Potato growers can create a clean start to crops by ensuring the foundation of their broad-leaved weed control plan is an e ective herbicide. But, as with diquat, timing is key to success.

Capable of controlling weeds typical of a broad range of potato-growing soils and regions, Shark is highly e ective when used either alone or in in a mix with other residual herbicides when applied just prior to crop emergence, says FMC commercial technical manager Je Fieldsend (right).

It is recommended that Shark is applied at 5–10% emergence (5% emergence on early varieties and 10% emergence on maincrop varieties) but operators should be cautious when it comes to timings, warns Mr Fieldsend.

“While application at 5–10% emergence is attractive in terms of timing exibility, it is best to use the product as soon as the weed ush has developed and not risk applying too late; crops are moving very quickly around this time and late applications can knock them.” Trials conducted by FMC and AHDB have proved that Shark is extremely crop safe when applied at the correct timing. However, if application is delayed onto emerged potato plants greater than 5–10%, necrotic spotting will occur, which will be quickly outgrown, leading to no long-term e ects on vigour or yield.

“Shark is particularly e ective on a wide range of broad-leaved weeds, notably polygonum species, cleavers, annual nettle and speedwells up to the young plant stage when applied at 0.33-litres/ha rate, with excellent activity being observed within 2–3 days following application,” Mr Fieldsend adds.

“It is suitable to use with all potato varieties and crop types, including both ware and seed, and in terms of application has no bu er zone requirement; plus it is rainfast within an hour.”

The further opportunity to apply Shark onto non-cropped land prior to planting is also a tried-and-tested method of tidying up both grass and broad-leaved weeds, allowing for a clean start.

“Mixing Shark with glyphosate allows growers to get on top of di cult weeds that glyphosate does not control when used alone,” advises Mr Fieldsend. “There is real improvement in the control of annual nettle, cranesbill and willowherbs with the mix, and can allow for lower rates of glyphosate to be used. A onemonth interval following application exists when using this mix prior to planting a crop, but this is not an issue in most situations.” of a broad range of potato-growing soils and regions, Shark is highly e ective when used either

It is recommended that around this time and late applications can knock them.” Trials conducted by FMC and AHDB have proved that Shark is extremely crop onto emerged potato plants greater than 5–10%, necrotic spotting will occur, (right) reports: “Shark has been a reliable diquat coming back strongly

Agronomist’s viewpoint

Agronomist Rob Ramsey (right) reports: “Shark has been a reliable diquat replacement for my customers, and we’ve seen good results from welltimed applications, with the crop coming back strongly even when 5–10% has emerged, so there is a fair window of application, much like there was with diquat.”

New elds rented by growers as clean potato land bring new weed management challenges, points out Mr Ramsey, who provides agronomy advice to around 160ha of fresh and processing potato crops as part of 1,600ha he crop-walks in north Lincolnshire.

“We’re often up against unknowns when dealing with management of new land in terms of weed burdens, among other factors, so beginning with clean land is important.

“While it doesn’t have any grassweed activity as such, it picks up on those weeds that residual chemistry is a bit weaker on, and gives us a good, clean start to the crop, helping it to get away strongly. And, if the weed burden is low, there is scope to tweak the rate a little, perhaps reducing it to 0.3 or even 0.25-litres/ha if dealing with only small weeds, which is often the case.

“Potato land rents aren’t cheap, so it’s important to invest what’s necessary to get maximum yields. Add a residual such as Artist ( ufenacet + metribuzin) or Praxim (metobromuron), plus perhaps Defy (prosulfocarb), for the addition of grassweed and further broad-leaved weed control, and we have a good belt-and-braces approach for a clean start to the crop.” FG