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Hawai'i Forestry Extension

Characterization of host suitability of forest tree species to plant-parasitic nematodes


Brent Sipes, Department of Plant and Environmental Protection Sciences, UH-CTAHR
Donald Schmitt, Department of Plant and Environmental Protection Sciences, UH-CTAHR
J. B. Friday, Department of Natural Resources and Environmental Management, UH-CTAHR


Plant-parasitic nematodes often cause severe injury to forest and landscape trees but the damage is undiagnosed and uncontrolled. This project will identify plant-parasitic nematodes that are damaging to forest trees in Hawaii and disseminate this information.

Contact Dr. Brent Sipes (sipes@hawaii.edu)
Phone: 808-956-7813
Fax: 808-956-2832

OBJECTIVES

  1. To elucidate the host status of the trees Acacia koa, Eucalyptus grandis, E. urophylla, and the hybrid E. uro-grandis, E. deglupta, and E. microcorys to the root-knot nematodes Meloidogyne javanica and M. incognita, the reniform nematode Rotylenchulus reniformis, the lesion nematode Pratylenchus penetrans, and the ring nematode Criconemella sp. If resources allow, a species from the Meliaceae, such as Toona ciliata, Swietenia spp. or Khaya spp. will be evaluated.
  2. To determine the plant-parasitic nematodes present in conservation forests, commercial agro forestry plantations, and small holder forests.
  3. To disseminate findings of the host-status of forest and native trees to nematodes.

APPROACH

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Seedlings of the trees will be procured from clean nurseries, transplanted into clay pots filled with sterile media, and inoculated with root-knot (5,000 eggs/pot), reniform (5,000 eggs/pot), lesion (3,000 mixed stages of juveniles and adults/pot), or ring nematodes (2,000 mixed stages of juveniles and adults/pot). Seedlings will be transferred to the greenhouse and grown for 6 months. An uninoculated seedling of each tree species will serve as a control. Plant height measurements will be taken at 3 months and height, wet and dry weights will be recorded at the end of the experiment. Nematode population densities will be determined at plant harvest. Nematodes will be extracted from soil by elutriation and centrifugation and from roots by mist extraction. Treatments will be arranged in a randomized complete block design with 10 replications per treatment. Data will be analyzed using appropriate statistical procedures for the experimental design. The ring nematode will be identified to species if possible. Sampling efforts will focus on the island of Hawaii. Conservation forests will be randomly sampled at three elevations. Samples will be collected from a 1 ha area, composited, and sifted to separate roots from soil. Three to four ha will be sampled in each forest. Three commercial forestry plantations will be sampled in a similar manner. Six small land holders will be samples with one sample per grower. The Hamakua experiment station will be sampled intensively based upon geographic and use criteria. State and federal nurseries which grow out native species for outplanting in forest reserves. Nematodes will be extracted from the soil by elutriation and centrifugation. Roots will be placed in a mist chamber. Samples will be viewed under the microscope to determine what kinds of plant-parasitic nematodes are present. A fact sheet will be produced detailing plant host-status to plant-parasitic nematodes. Pictures and tables will be used to show nematode damage. The fact sheet will be available as hard copy and html. If evidence that nematodes are damaging plants is found, a workshop with forest nursery growers on how to combat nematodes will be held.

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Updated 28 October 2002

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