Seasonal Population Dynamics of Selected Plant-parasitic Nematodes as Measured by Three Extraction Procedures

Seasonal fluctuations in field populations of Meloidogyne spp. (M. incognita and M. hapla), Pratylenchus zeae, Criconemoides ornatum, Tylenchorhynchus claytoni, Belonolaimus longicaudatus, and Helicotylenchus dihystera were determined monthly for 1 year by three extraction procedures. Baermann funnel method (BF) gave highest recoveries of Meloidogyne spp. and P. zeae during summer and fall, but centrifugal-flotation (CF) and sugar-flotation-sieving (SFS) usually yielded higher numbers of these nematodes during winter and spring. CF was t h e only effective method for recovery of C. ornatum with maximum numbers occurring in September. Recoveries of T. claytoni were similar with all methods in summer and fall. However, BF gave low numbers in winter and spring, whereas population peaks with the flotation methods occurred in January and February. All methods gave similar recoveries of B. longicaudatus with highest numbers occurring in November and December. This species declined drastically in late winter and spring. Yields of H. dihystera were similar for all three methods with CF consistently higher and the major peaks occurring in August.