21 July 1995

Low dose rates no problem for new fungicides

By Robert Harris

NEW fungicide chemistry can succeed even at very low rates, visitors to Aubourn Farmings agronomy open day at Dennis Westons Willoughby Farms, near Alford, Lincs, found last week.

A range of winter wheats was used to compare the performance of a multi-low dose fungicide programme using Opus (epoxiconazole) with a more conventional method, explained company agronomist, Bridget Carroll.

Half the plots were treated with four applications of Opus at 0.2 litres/ha (0.14pt/acre) at first node, second node, flag leaf just visible and pre-flowering (GS31, 32, 37 and 55). The rest received a standard treatment of reduced rates of Folicur (tebuconazole) and Bravo (chlorothalonil) at GS 31, Opus at GS39 (flag leaf emerged) and Folicur at GS55.

"I wanted to see how Opus would behave in this system. There was no information available in this country, so we set up our own trial based on French ITCF work. Plots look good, and I expect it to do well."

Lighter land

She has used the approach commercially this year, adapting rates to suit disease pressure and timing. "It seems to suit lighter land with lower yield potential. It has worked exceptionally well, and at £23.47/ha (£9.50/acre) its a very cost-effective approach provided the user can cope with the extra management." The standard treatment cost £35.33/ha (£14.30/acre) more.

Repeat low-dose Opus fungicide offers promising disease control and has already produced good commercial results, says Bridget Carroll.