Close cereal cropping. Effect of cultural treatments of wheat on eyespot, lodging, take-all and weeds

Trials are reported on the effect of various treatments on the control of eyespot (Cercosporella herpotrichoides[Pseudocercosporella herpotrichoides]), lodging, take-all (Ophiobolus graminis[Gaeumannomyces graminis]) and weeds in the 4th, 5th and 6th successive winter wheat crops following a crop heavily infected with eyespot. Sulphuric acid spray at a rate of 100 gal. of 12.5% B.O.V. by vol. per gal. had no effect on straw yields, except in one year when it increased straw yields by an average of 17.6 cwt. per acre over controls. Lodging was markedly decreased by spraying; in 1946 and 1948 control plot and sprayed plot lodging percentages were 90 and 31, and 58 and 3, respectively. Weeds were markedly reduced. The most effective time of spraying was in early spring, before the eyespot pathogen had penetrated the first two leaf sheaths. Ammonium sulfate applied soon after the spring spraying increased both straw yields and the prevalence of eyespot, both factors contributing to significant increases in lodging percentages. The nitrogen applications increased grain yields only when lodging was slight, or absent. In trials to determine the combined effect of seed rates and nitrogen application on the prevalence of take-all, the average percentage of given areas covered by take-all following seed rates of 1.5, 2.5 and 3.5 bu. per acre, with no nitrogen applied, was 20, 30 and 65% respectively. Where the same seed rates were employed and 4 cwt. of ammonium sulfate applied per acre, take-all percentages were reduced to 2, 5 and 9% respectively. Wheat yields of over 29 bu. per acre were maintained up to the sixth successive crop by optimum treatments of spraying, early nitrogen applications and thin sowing. The importance is stressed of early spring applications of nitrogen on light land where take-all is prevalent.-P.J.B.