Abstract
Young plants of one species of each of 17 genera (Aesculus, Ailanthus, Celtis, Fagus, Ginkgo, Gleditsia, Juglans, Koelreuteria, Liquidambar, Madura, Magnolia, Pyrus, Robinia, Sassafras, Sophora, Ulmus, Zelkova) and three species each of Betula and Prunus were inoculated with the four common root-knot nematodes (Meloidogyne spp.). Of 23 tree species tested, the majority were susceptible to one or more of the nematodes but Ailanthus altissima, Fagus grandifolia, Gleditsia triacanthos, Juglans nigra, Liquidambar styraciflua, Madura pomifera, Magnolia grandiflora, Prunus avium, Pyrus calleryana, and Sassafras albidum exhibited a tolerant or resistant response to all of the nematodes.
Root-knot nematodes (Meloidogyne spp.) may stunt the growth of young plants and form disease complexes with certain soil-borne fungal disease pathogens. Our understanding of the influence of these nematodes on landscape trees has been limited by a lack of knowledge of the potential tree hosts of these pests. In orderto rectify this situation, we have published, in recent years, a comprehensive compilation of the world literature on this topic (3) and major surveys of nematode susceptibility in species of Salix(4), Quercus (1), and Acer (2). There are many other important tree genera in which extensive surveys would be desirable, but such analyses could constitute an almost “never-ending” series. On the other hand, there are many tree genera in which only one, or a few, species are widely grown in urban landscapes. Therefore, in the present study, we have limited our nematode inoculations to some of these species.
The following discussion of previous reports of root-knot nematodes on the 19 tree genera tested in the present study (see Table 1) is based on the data presented in our earlier compilation (3), rather than being referenced to the original literature.
Response of various landscape trees to inoculation with root-knot nematodes (Meloidogyne spp.)1/
There have been no reports of any root-knot nematodes parasitizing Ailanthus altissima, Celtis occidentalis, Fagus grandifolia, Madura pomifera,or Sassafras albidum.
Betula nigra, Ginkgo biloba, Gleditsia triacanthos, Koelreuteria paniculata, Magnolia grandiflora, Prunus avium, Prunus cerasifera, Prunus mahaleb, Sophora japonica, and Ulmus parvifolia have been noted only as hosts of unidentified nematodes.
There have been no reports of Aesculus flava, Betula platyphylla var. japonica, Betula populifolia, or Pyrus calleryana as hosts of any of the common root-knot nematodes, although other species in these genera have been noted as hosts of unidentified or rare nematode species.
Both Robinia pseudoacacia and Zelkova serrata have been noted as hosts of one or more of the common root-knot nematodes.
Liquidambar styraciflua was not susceptible to inoculations with the common root-knot nematodes but was reported as a host of an unidentified species.
Juglans nigra was reported as a host of M. ovalis Riffle and an unidentified nematode species.
Materials and Methods
The seedlings used in this study were grown from seed collected from one tree of each species. Plants of Betula nigra ‘Heritage’ were grown from rooted cuttings. Nematode inoculation procedures were as outlined in previous reports (1,2,3) and evaluations made 70 to 90 days after inoculation.
Results and Discussion
The results of our tests are given in Table 1. It is noteworthy that seedlings of many species exhibited a tolerant or resistant response to all of the nematodes. Gleditsia triacanthos and Magnolia grandiflora are two of the most widely planted native American landscape trees, and both have been reported as hosts of unidentified root-knot nematodes (3). Our findings indicated that both species were completely resistant to parasitization by the common nematode species. Thus, it would be of great scientific interest if nurserymen or arborists who find nematode galls on the roots of these trees would collect such material and bring it to the immediate attention of nematologists in their area to determine if new and heretofore unknown nematode species are involved.
Acknowledgments
The authors would like to thank Monique L. Petersen, Biological Technician,forherassistance in this study.
- © 1993, International Society of Arboriculture. All rights reserved.
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