Comparison of the effects on eyespot in wheat of fungicides applied to the foliage or shoot bases at different times

Abstract

The control of eyespot (Pseudocercosporella herpotrichoides (Fron) Deighton) is most effective after application of carbendazim (Hampel & Lücher, 1973; Taylor & Waterhouse, 1975) or prochloraz (Marshall & Ayres, 1986) at growth stages (GS) 30–31 (Zadoks, Chang & Konzak, 1974), although some control occurred after applying prochloraz with carbendazim at GS 37–49 (Marshall & Ayres, 1986). Growers in the U.K. are advised to apply eyespot fungicides only when severe disease is expected. This forecast is usually made at GS 30, and spraying is recommended when two or more leaf sheaths have been penetrated on at least 20% of shoots (Anon. 1985). However, subsequent weather conditions may result in severe eyespot developing when no spray was recommended, or may not favour eyespot and result in fungicide being wasted.