12 March 1999

Strob watch…

CEREAL growers are being urged to use strobilurin fungicides more prudently in a bid to prevent diseases developing resistance to the new chemistry.

Monitoring is already underway in cereal growing areas to ensure any outbreaks of resistance in the UK are spotted early.

New guidelines from the industrys Fungicide Resistance Action Committee were issued on Tuesday, in response to the discovery of strob-resistant strains of wheat mildew in northern Germany last year.

Car-mounted spore traps used to check for resistance throughout Germany found up to 45% of spores were resistant in one area. Similar checks in East Anglia found no resistance last year. Further checks are expected this year.

Although mildew is the main concern, the defence principles are equally appropriate for all diseases, says Zenecas Steve Heaney, chairman of FRACs new strobilurin and related compounds (STAR) working group. Guidance is based on applying a full dose across the season, using mixtures and appropriate timings and no more than two strob-containing sprays a season.

Zeneca is now advocating a maximum of two applications of Amistar (azoxystrobin) in any season and issuing detailed advice on mixture partners.

&#8226 Full details next week.