HIGH LIGHT intensity, low disease pressure, and an abundant supply of water for irrigation makes the Canterbury Plain in New Zealand’s South Island the place to be if you want to grow world beating wheats.

So say a host of UK experts who have seen the conditions there first hand, including, TAG director Jim Orson, who was working in New Zealand just before Christmas.

“It is the coincidence of high light intensity with a long grain-fill that gives such high yields,” he explains.

Plant breeder John Blackman, formerly of CPB Twyford and now working on his own breeding programme in the UK and New Zealand, also marvels at the conditions.

“The average yield in the UK is about 8t/ha; the average here should be 14t. The light intensity is tremendous.”

Nick Poole, formerly of ARC and now working for New Zealand’s levy-funded Foundation for Arable Research (FAR), agrees, but also highlights the extremes that can be seen.

“Irrigation is of huge importance, especially in seasons like last year. By and large the soil textures here are lighter [than in the UK] so it doesn’t take long before a Nor”wester blowing straight from Australia sucks all the moisture out of a crop.”

Having been forced over the 3000m Southern Alps such winds are hot and dry. “Evapotranspiration rates can be extremely high, typically 5-6mm/day in the summer months, and some people were claiming as much as 9mm/day during the 33-34C days we had last year. Non-irrigated wheat yields tumbled to as little as 3t/ha.”

Agronomically, wheats are well looked after by growers who have progressed in leaps and bounds in the past 10 years, adopting autumn varieties and embracing the concepts of canopy management, says Mr Poole.

Diverse rotations, often including forage seed crops and autumn grazing, mean soil residual nitrogen is generally higher than in the UK. Up to 150kg/ha is not uncommon.

Apart from that, later sowing means winter wheats are generally a little easier to manage.

“There is a longer intercrop period which helps reduce disease pressure, and there is more of a focus on integrating arable production with livestock which probably helps with weeds.”

Bromes have become the main grassweed issue as more farms have switched to autumn sowing, and due to a lack of specific chemistry such as Monitor or Attribut.

Wild oats have been well controlled, historically by roguing and more recently with sprays, and blackgrass is not present. Ryegrass has not become a problem weed despite widespread inclusion in rotations.

“Wheat in ryegrass seed crops is more of an issue for growers than ryegrass in cereals, though the ability to burn stubbles is a huge plus.”

Diseases

Key wheat diseases are the same as the UK, but with rusts more of a problem than septoria, says Mr Poole.

Recent FAR work on fungicide timings, and the emergence of strobilurin resistance in mildew and septoria in Europe, means it now suggests growers adopt a “straddle” approach to timings.

“Disease loading at GS31/32 tends to be much lower here, so instead of starting the fungicide programme at a traditional T1 timing targeting leaf three, you start on leaf two, GS33, and follow that with a fungicide on the flag leaf and ear, at ear emergence. The aim is to get two strobs to do the work of three,” explains Mr Poole.

He stresses it is a “straddle”, and not the “stretch” timing much talked about in the UK.

“You must not let the second spray go later and later; the gap should only be three weeks.”

In barley, rhynchosporium, or scald, is the dominant disease, though again rusts can be an issue. Three-way mixes of triazole, strob and carbendazim are recommended under high disease pressure.

Slugs are generally less of a problem than in the UK. Despite later sowing BYDV pressure can still be high due to the generally milder climate.

Gaucho is used on earlier sowings, with the added benefit that it has some affect on arguably New Zealand”s number one pest, the grass grub, he notes. “It is widespread and can decimate affected crops, including cereals, grasses and clovers – the whole lot.”

Estimated damage runs at $25-$90m/year (£9.4-£33.5m) despite organophosphate sprays and a bacterial biocontrol agent.

Nearly all growers employ an agronomist, FAR chief executive Nick Pyke estimating 80% are still using agrochemical trade-linked people.

However, FAR Arable Update newsletters, and information presented at up to nine open days a year, give growers sufficient information to keep their advisers on their toes, he says.

“Very few growers do their own agronomy without some sort of sounding post,” he adds.

fwcropsfwi@rbi.co.uk