TABLE CONTENTS

Diagnostics and Management to Protect California Agriculture from
Invasion of False Root-knot Nematode (Nacobbus spp.)
Subbotin, S.A. (1,2), M. Mundo-Ocampo (1), T. Mullens (1), P.A. Roberts (1) &
J.G. Baldwin (1)
(1) Department of Nematology, University of California, Riverside, CA 92521; (2) Plant Pest Diagnostic
Center, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832.
As a potential invasive plant nematode, Nacobbus spp., the false root-knot nematode, poses a
significant, urgent threat to California crops and agricultural trade. While not yet established
in California agriculture, Nacobbus is established in neighboring areas, including other parts
of the western United States, Mexico, and Latin America where it causes serious crop loss.
The threat is exacerbated by diversity in pathogenicity and host range and by lack of quick,
reliable diagnostic tools to support routine regulatory operations. Herein we present the
analysis of the ITS-rRNA gene sequences of several populations of Nacobbus spp.
originating from North and South America. PCR-ITS-RFLP diagnostic profiles and PCR with
specific primers were developed as practical tools to distinguish some isolates. Presence of
several cryptic species and species boundaries within Nacobbus are presented based on
molecular, morphological and morphometrical studies. Diagnostic characterization of
Nacobbus isolates is a first step toward testing these isolates against specific crop and weed
hosts to recognize potential natural reservoirs as well as to identify sources of crop resistance.
A combination of diagnostic profiling with host and resistance specialization will be used to
support the design of management strategies.
5 th International Congress of Nematology, 2008 333