3 July 1998

Dual pgr spray approach looks all set to pay off for growers

Barley lodging, disease

control and sugar beet

agronomy were key themes

at the Crop Care Groups

annual open day at Saxham

near Bury St Edmunds.

Edward Long reports

ANOTHER wet June highlights the need for well-timed growth regulator on winter barley, the Saxham trials showing the value of a two-spray approach.

After the mild winter there was a lot of soft growth in the spring and early uptake of nitrogen occurred before a sufficiently robust root system developed. That exposed the crop to root lodging and then stem lodging risk increased as thick crops became top-heavy, explains Crop Cares Colin Myram.

"Lodging was bad last year. But in many areas it is worse this season. Since the previous bad year the lodging-susceptible varieties Fanfare and Gleam have become more popular."

In 1997 trials almost 100% of the untreated crop went down. A single full rate spray of Terpal (2-chloroethylphosphonic acid + mepiquat chloride) at GS39 cut lodging to about 40%. But a two-pronged approach with half rate 5C Cycocel (chlormequat + choline chloride) and Moddus (trinexapac-ethyl) in March followed by full rate Terpal in early May reduced it to below 5%.

Using 1998 chemical costs and a barley price of £80/t, the company calculates a full rate Cycocel treatment would be worth £5.50/ha, a full-rate Moddus £51, a half rate Terpal £70 with a full rate £10/ha less. A full rate Cycocel + Terpal would bring in an extra £73, but there would be £148/ha more for a twin application of half rates Cycocel/Moddus followed by full rate Terpal.

"Winter barley growers, particularly those aiming at a malting market, cannot afford to let crops go flat. In a high lodging risk the no-holds-barred treatment was easily the most cost-effective. But where there is no lodging the extra yield still covers the cost of chemical, and the second application is normally put on before there is any risk of crop stress," Mr Myram says.

Winter barley backed by two pgr sprays is set to outstrip crops which received just one, says Colin Myram.