Self-interactions of Meloidogyne hapla and of Heterodera schachtii on Beta Vulgaris
Double inoculations of sugar beet with larvae of Meloidogyne hapla resulted in a higher galling incidence in only one treatment than did a single inoculation using the same number of larvae. Double inoculations with larvae of Heterodera schachtii, however, resulted in three- to five-fold more cysts in most cases than did single inoculations using the same number of larvae. In general, plants died more quickly after double inoculations than after single inoculations of the same total number of either nematode. Ratios of total soluble carbohydrates to reducing carbohydrates were lower in multiple inoculated treatments than in other treatments. Plants infected with M. hapla had lower quantities of B, K, and P in leaf tissue than noninoculated plants, but no differences were correlated with type of inoculation. Plants inoculated with H. schachtii had lower quantities of B, K, and Mg than noninoculated plants. Also, quantities of Mn, Cu, and Zn were much lower in plants inoculated twice with H. schachtii larvae than in plants inoculated with the same total number of larvae in a single dose. Key Words: Cyst nematode, root-knot nematode, mineral elements, carbohydrates, double inoculations, parasitism, sugar beet.