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Seasonal Population Fluctuations of Meloidogyne spp. and the Pasteuria penetrans Group in Kiwi Orchards. S. Verdejo- Lucas, Research Nematologist, Departamento Patología Vegetal, IRTA, Crta de Cabrils s/n, 08348 Cabrils, Barcelona, Spain. . Plant Dis. 76:1275-1279. Accepted for publication 29 July 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-1275.

Seasonal population fluctuations of the nematodes Meloidogyne incognita, M. arenaria, and M. hapla and the nematode-parasitic bacterium Pasteuria penetrans were monitored monthly in two kiwi orchards (A and B) during 1989 and 1990. Nematode numbers in soil fluctuated little, but there was a trend toward reduced numbers at the end of the study, with higher numbers in winter than in summer. The percentage of root-knot nematode juveniles with spores ranged from 0 to 8 (* = 2) in orchard A and from 0 to 18 (* = 7) in orchard B. The percentage of parasitized females ranged from 0 to 12 (* = 4) in orchard A and from 0 to 28 (* = 11) in orchard B. The total number of females per gram of roots and the percentage with P. penetrans were positively correlated in orchard B. Parasitized females and juveniles with spores were also correlated in this orchard during 1990. In vitro tests indicated that spores, whether from orchard A or B, adhered more readily to juveniles from orchard B than from orchard A.