The Relationship Between Population Density of Heterodera schachtii, Soil Temperature, and Sugarbeet Yields
Cooke, D.A.; Thomason, I.J.
Journal of Nematology 11(2): 124-128
1979
ISSN/ISBN: 0022-300X PMID: 19305544 Document Number: 141490
In 2 glasshouse experiments the relationships between sugarbeet root dry weight (y, expressed as a percentage of the maximum dry root weight) and preplanting populations of Heterodera schachtii (Pi) were described by the equation y = 100 (Z)Pi-T, in which Z = a constant slightly smaller than 1, and T = the tolerance limit (the value of Pi below which damage was not measurable). T varied with temperature and was 65 eggs/100 g soil at 23 and 27 deg C and 430 eggs/100 g soil at 19 deg C. At 15 and 31 deg C there was no loss of root dry weight up to the maximum preplanting populations tested. In a field experiment in the Imperial Valley, California, USA, the relationship between root yield (y) and Pi was y = 100 (0.99886)Pi - 100 and the tolerance limit was 100 eggs/100 g soil. [AS].