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Disease Note. Reproduction of Northern Root-Knot Nematode (Meloidogyne hapla) on Marigolds. J. D. Eisenback, Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061. Plant Dis. 71:281. Accepted for publication 9 December 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0281E. Marigolds (Tagetes spp.) are often recommended to home gardeners
for the control of root-knot nematodes. Eleven populations of
Meloidogyne hapla Chitwood from various geographic origins and
cytological forms, including races A and B (2), were tested for ability to
reproduce on Tagetes erecta L. 'Carnation.' One field population from
Virginia, cytological race A with a haploid chromosome number of 17,
caused extensive galling and lateral root proliferation; galls and egg
masses exceeded 500 per plant. Three of the populations caused single
galls and egg masses on two or three of the six replicates, but most
populations failed to reproduce. Previous studies revealed that T. erecta
did not reduce M. hapla populations in the soil; reproduction by the
nematode on marigold, however, was not demonstrated (1). If more M.
hapla populations are detected that can parasitize various T. erecta
cultivars and other species of Tagetes, the recognition of a marigold
race of M. hapla may be necessary, and recommendations on the use of
Tagetes spp. may need qualification. |