16 October 1998

Wheat adjuvants pay

ADJUVANTS proved their worth as wheat growth regulator aids in Scottish trials this season.

Four years of work in 49 trials by CSC Crop Protection show the average yield advantage of using Meteor (chlormequat + choline chloride + imazaquin) instead of straight chlormequat as a straw strengthener is 0.29t/ha (2.3cwt/acre), says regional agronomist Mark Ballingall.

Last seasons trials show that spending less than £10/ha (£4/acre) on Arma and Slippa additives respectively for a split Meteor treatment cut lodging at harvest by 20% and boosted output 10%.

The basic treatment of 1litre/ha at mid-tillering (GS23) and 1.5litres/ha at first node (GS31) cost about £14.50/ha (£5.90/acre). Straight chlormequat cost £6/ha (£2.40/acre).

Using 0.2 litres/ha of Arma at the first Meteor timing and 0.1litre/ha of Slippa at the second added £8.90/ha (£3.60/acre) to costs.

While adjuvants have similar effects, the choice at each timing reflects the fact that in practice Arma works well with trace elements also often applied early, says colleague Keith Dawson. Slippa appears more useful late, especially where strobilurin fungicides are used, he notes.

The relatively weak strawed variety Charger was chosen to emphasise any differences between treatments. The untreated crop was nearly 100% lodged by harvest.

"Meteor consistently outperforms chlormequat," says Mr Ballingall, "And the adjuvants clearly improve it for a marginal extra cost."

Growth regulator trial

Untreated Meteor at Meteor + adjuvants

GS23 & 31 at GS23 & 31

Lodging (Aug 14) 15% 4% 0%

Lodging (at harvest) 95% 75% 55%

Relative yield* 100 113 123

* Untreated 8.2t/ha (3.3t/acre)