Effects of nitrogen applied at different dates, and of other cultural treatments on eyespot, lodging and yield of winter wheat. Field experiment 1952

Abstract

Lodging and yield of winter wheat were studied in a factorial experiment on land infested with the fungus Cercosporella herpotrichoides Fron. causing Eyespot. Two varieties, Squareheads Master 13/4 with long, and Bersée with short, straw, were compared at two seed rates; sulphate of ammonia was applied at 0, 2, and 4 cwt./acre at four different dates; four of the 8 blocks of 10 plots were sprayed in March with sulphuric acid to control eyespot.Lowering the seed rate from 3 to 1½ bushels/acre decreased eyespot and the area lodged and increased the mean yield of the 2 varieties by 4·9 cwt. in unsprayed and 2·1 cwt./acre in sprayed plots. Spraying the variety Squareheads Master decreased the straws with severe lesions from 66 to 17%, decreased the area lodged from 95 to 36%, and increased grain from 22·4 to 32·4 cwt./acre; spraying Bersée decreased severe lesions from 56 to 15%, decreased lodging from 54 to 1% and increased yield from 32·6 to 43·5 cwt./acre.The mean percentage infection at harvest was little affected by nitrogen applied in March, April or May, but was decreased by nitrogen applied in October. In contrast, the time of applying nitrogen greatly affected the weight of straw and the extent of lodging, both of which were increased more by top dressings in March and April than by those in May. Plots that received nitrogen in March and October had similar weights of straw, but the latter, with less eyespot, lodged less. Where lodging was slight, grain yields were increased equally by nitrogen applied at each date; where lodging was extensive, yields were depressed by dressings in March and April, and increased by those in October and May. Sulphate of ammonia, applied at 0, 2 and 4 cwt./acre to sprayed (upright) plots of Bersée, yielded respectively 36·8, 42·9 and 47·3 cwt. of grain, whereas applied to unsprayed (completely lodged) plots of Squareheads Master yielded only 22·4, 22·0 and 22·9 cwt./acre respectively.