INCREASINGLY, attempts are being made to afforest difficult sites including prairie and steppe lands, peat bogs, Calluna heaths and industrial wastelands. In the United Kingdom the Forestry Commission is planting Sitka spruce (Picea sitchensis (Bong. Carr.) and Lodgepole pine (Pinns contorta Loud.) on land subject to periodic or protracted waterlogging and, notwithstanding the use of improved techniques of planting and site preparation, these species tend to be shallow rooted and liable to ‘wind blow’1. In these conditions the establishment of nursery-grown seedlings is problematical. As long ago as 1917, Melin2 noted that while Pinus sylvestris L. and Picea abies (L.) Karst. transplants, used for afforesting freshly drained peat bogs, were without mycorrhizas they remained stunted. Growth accelerated as soon as these structures began to appear, however, presumably with the development of effective amounts of fungal inocula which may have been initially absent.