Fongicidal Control of Yellow Rust on Winter Wheat in 1972: an Assessment of Farmers' Opinion

Abstract

SUMMARYIn 1972 yellow rust severely affected 23 per cent of the total area of winter wheat covered by a postal survey and 56 per cent of the area of cv. Joss Cambier, the cultivars most seriously affected. Crops rated by growers as severely infected had a mean yield 0.90 t/ha (7.2 cwt/acre) less than that for those not so rated, and for unsprayed crops of equivalent ratings the difference was 0.88 t/ha (7.0 cwt/acre). Severely infected crops which were sprayed, with fungicide had a mean yield 0.18 t/ha (1.4 cwt/acre) greater than those not sprayed, and for cv. Joss Cambier this difference was 0.34 t/ha (2.7 cwt/acre).Of the total crop area surveyed, 9.0 per cent was sprayed, comprising mainly the cv. Joss Cambier of which 26 per cent of the area was sprayed. Of the sprayed crops, 48 per cent received an aerial application: the mean yield of these crops was 0.45 t/ha (3.6 cwt/acre) greater than those sprayed from the ground. For cv. Joss Cambier the difference was 0.50 t/ha (4.0 cwt/acre), suggesting that ground spraying caused some mechanical damage, and perhaps that aerial application was more timely and gave better coverage.Of September‐sown crops, 31 per cent were rated as severely infected compared with 26 percent of the October‐sown crops and 17 per cent of the later‐sown crops.No conclusions could be drawn from the effect of spray timing or fungicides used. The growers considered that spraying had been worth while on 69 per cent of crops sprayed.The authors are indebted to the many farmers who responded to the request for information. They also thank Mr. W. Campbell, A.D.A.S., Wolverhampton, Mr. H. J. Wilcox, A.D.A.S., Cambridge, and Mr. R. S. Hutley and the M.A.F.F. Statistics Branch, Guildford, for consultation in devising the survey and for the statistical analysis, and Mr. C. S. Harper, A.D.A.S., Reading, for guidance in the interpretation of this data.