Abstract: We have found that mycorrhiza formation by some strains of T. aestivum is suppressed by the use of high-Ca pelletized lime to raise the pH of greenhouse potting medium, as compared with the use of natural crushed dolomitic limestone. We have also found that seedlings grown under a novel process (RPM􊑒 ) for producing very large root systems in bark-based media failed to become as well colonized by T. aestivum as did seedlings grown under a more typical system in a peat-based medium in book planters .We have followed ectomycorrhiza community development on both RPM􊑒 and more typically produced seedlings for two years in the field . Competing ectomycorrhizal species dominated RPM seedlings two years after outplanting , whereas T. aestivum remained dominant on more typically produced seedlings .Mycorrhizae of four Tuber spp . have been detected in this plantation ( i. e ., T. whetstonense, T. maculatum, T. rufum , and T. lyonii ) . These are the first records of T. whetstonense , T. maculatum, and T. rufum occurrence in MO .Mycorrhizae and ascocarps of T. lyonii had been found in nearby plantings of Corylus seedlings in 2005 , and again in 2007 . A third seedling production process (Missouri Gravel Bed) shows promise in a pilot study with T. aestivum and warrants further study .
Selection of T. melanosporum vs . T. aestivum as the target truffle species for a specific location is complicated by the uncertainty of future climatic conditions. Different mulching practices modify soil temperature and moisture, and may provide clues to the environmental tolerances of T. aestivum and T. melanosporum . We are comparing the effects on soil temperature and soil moisture of water-permeable weed barrier fabric vs. a thin layer of calcareous gravel , as compared to no soil surface treatment .

Key words: Truffle cultivation