The Relationship of Heterodera schachtii Population Densities to Sugarbeet Yields

G. D. Griffin

Abstract


Sugarbeet yields were contpared with field populations of Heterodera schachtii Schmidt. The correlation between sugarbeet yields and viable larvae/g of soil was negative and high, but that between sugarbeet yields and viable cysts/g of soil was lower. Sugarbeet yields were also compared with H. schachtii populations by years of rotation with a nonhost crop. The coefficients of correlation (r) between yield and viable larvae/g of soil were negative and high: 0 yr of rotation, -0.935; 1 yr, -0.922; 2 yr, -0.954; 3 yr, -0.935; and combined years, -0.965, with 95% confidence limits of -0.91 to -0.98 for combined years. The comparable correlation coefficients between yield and "viable cysts"/g of soil were negative and lower: 0 yr of rotation, -0.151; 1 yr, -0.022; 2 yr, -0.490; 3 yr, -0.456; and combined years, -0.586, with 95% confidence limits of -0.22 to -0.80 for the combined years. Key words: sugarbeet cyst nematode, larvae g/soil, cysts/g soil, Beta vulgaris, sugarbeet yields, crop rotation.

Full Text:

PDF