Performance of Mycorrhizal Products Marketed for Woody Landscape Plants

Abstract

Commercial products containing propagules of arbuscular mycorrhizal fungi (AMF) are widely marketed to improve woody plant performance in the landscape. However, the infectivity of these products has rarely been subjected to independent testing. We evaluated commercial AMF inoculants in a series of greenhouse experiments using corn (Zea mays), sorghum (Sorghum bicolor), trident maple (Acer buergerianum), and sweetbay magnolia (Magnolia virginiana) as host plants. In corn and sorghum, colonization rarely exceeded 5% when plants were treated with commercial inoculants. In contrast, viable lab-cultured inoculant of similar species composition yielded mean colonization percentages of 38 to 61%. Despite the near absence of colonization, commercial inoculants generally improved shoot growth and increased soil nutrient concentrations in a dose-dependent manner. Commercial inoculants had no effect on mycorrhizal colonization or shoot growth of trident maple or sweetbay magnolia liners. Product-treated magnolias grown from seed also developed little or no mycorrhizal colonization, whereas plants treated with a lab-cultured inoculant were 74% colonized. If commercial AMF inoculants are to receive broad acceptance as landscape soil amendments, manufacturers must demonstrate that their products can promote mycorrhizal colonization under the conditions of their intended distribution and use.

Variation in ectomycorrhizal fungal communities associated with Silver linden (Tilia tomentosa) within and across urban areas

“…How EcM communities vary across geographically separated urban areas and which local environmental variables drive EcM community composition and diversity in urban areas remains poorly understood (Newbound, Mccarthy and Lebel 2010). Such knowledge is crucial to devise site specific inoculation strategies for improving urban tree vitality (Bainard, Klironomos and Gordon 2011), as EcM inoculation studies so far have been performed either ex situ, and/or using commercially available inoculants, likely composed of mycorrhizal species that were not adapted to the urban environment, resulting in a poor effectiveness Wiseman, Colvin and Wells 2009;Fini et al 2011).…”