27 March 1998

PGR spray change helps keep wheat on its toes

WHILE crops all around fell to the ground last harvest, one Sunderland grower kept his winter wheat mostly upright with a combination of well-timed growth regulators.

Ian Davidson attributes bushel weights of 74-75kg/ha and a premium of £3/t on 300t for whisky-making to a new growth regulator strategy.

Local trials results and a discussion with Vernon Spinks of Independent Agriculture justified his switch from straight chlormequat at first node (GS31) to a mix of 0.2 litres/ha of Moddus (trinexapac-ethyl) with 1.1 litres/ha of 3C700 (chlormequat).

That worked particularly well on Reaper, the most lodging-prone variety grown on Mr Davidsons 162ha (400 acres), mainly heavy land Seaham Grange Farm.

Better crown root volume giving the crop better anchorage probably explains the good results, says Andrew Cottrell for Moddus maker Novartis. That view is supported by results from a company trial comparing Moddus with chlormequat alone and with chlormequat + choline chloride + imazaquin (as in Meteor), all at full label doses. Crown root volumes were 50, 32 and 38cc respectively, he notes. The untreated crop achieved 37cc.

Although chlormequat seems effective by checking plant height, in reality it stunts all areas of the plant including the roots, he claims. "As a result plants had shorter stems, but also weaker root systems, and so could still have been prone to root lodging. Reaper is a classic root lodger and really needs attention."

Full rate straight chlormequat costs £4.50-5/ha (£1.80-2/acre), whereas the Moddus combination used by Mr Davidson costs about £12/ha (£4.85/acre). But the potential returns easily justify the extra expense, Mr Cottrell maintains. &#42

Ian Davidson, who benefited from new, well-timed pgr sprays last year, and is looking forward to the same sort of results in 1998.