VA Mycorrhizal Inoculation of Landscape Trees and Shrubs Growing under High Fertility Conditions2

Abstract

This study investigated the effects of vesicular-arbuscular mycorrhiza (VAM) inoculation on the growth of landscape trees and shrubs under high-fertility nursery growing conditions. Four species of 1 year old trees, and rooted cuttings of nine species of shrubs, were inoculated with Glomus intraradices , or Glomus fasiculatum , or served as non-inoculated controls. The trees were transplanted to two high fertility, non-sterile field locations. Inoculation significantly increased the level of colonization in Acer platanoides , Sorbus aucuparia , Malus , and Fraxinus pennsylvanica , but did not enhance growth. The shrubs were containerized in a peat and bark medium with two levels of controlled release fertilizer. VAM inoculation significantly increased the level of colonization in Spiraea × bumalda , Syringa × chinensis , Prunus × cistena , and Cornus alba , while Weigela , Cotoneaster dammeri , and Potentilla parvifolia became well colonized without inoculation. Forsythia ovata and Viburnum opulus did not become significantly colonized. The growth of Syringa was stimulated by VAM inoculation during consecutive seasons, irrespective of fertilizer level. The growth of Prunus at the lower fertilizer level was significantly stimulated by inoculation even though control plants became highly colonized without VAM inoculation. Two years after inoculation, five species were transplanted to a second, non-sterile, field site to monitor the effect of inoculation on post transplant growth. G. intraradices significantly enhanced S. aucuparia caliper growth in the second year post-transplant.