Commercial production of tree seedlings often includes various biocidal soil treatments for disease control. Such treatments can be effective in eliminating or reducing disease organisms in the soil, but may also eliminate non-targeted beneficial soil organisms, such as mycorrhizal fungi, that improve seedling performance, both in the nursery as well as the outplanted environment. The arbuscular mycorrhizal fungal (AMF) relationship has been verified for some important western coniferous species such as incense cedar (Calocedrus decurrens [Torr.] Florin), coastal redwood (Sequoia sempervirens [D. Don] Endl), and western redcedar (Thuja plicata J. Donne ex D. Don).
This study was designed to determine the response of incense cedar after soil fumigation with and without the addition of phosphorous fertilizer and a commercial mycorrhizal inoculant containing Glomus intraradices. Incense cedar seedling performance was monitored in both the nursery and outplanting environments.
At the nursery, non-mycorrhizal seedlings had significantly less foliar phosphorous levels even when phosphorous fertilizers were applied. Mycorrhizal inoculation at the nursery significantly improved height and seedling survival on treated plots. Seedlings from the nursery beds were then outplanted on 2 reforestation sites. Mycorrhizal inoculation at the nursery improved survival and growth of seedlings at the outplanted site.
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