We have developed a research program that integrates several aspects related to the application of mycorrhizal technology in horticulture. We have conducted numerous trials to evaluate the effects of soilless mixes components, pesticides and fertilizers on mycorrhizal colonization and plant growth.
Corkidi, L., Bohn, J., and Evans, M. (2009). Effects of bifenthrin on mycorrhizal colonization and growth of corn. HortTechnology 19(4):809-812.
Abstract. The insecticide bifenthrin is a synthetic pyrethroid used for the production of nursery crops to suppress the red imported fire ant in Orange and Riverside counties in California. We investigated the effects of bifenthrin on mycorrhizal colonization and growth of corn. The application of bifenthrin had no detrimental effects on corn mycorrhizal colonization with VAM 80, a product used to inoculate California native plants. Mycorrhizal colonization reduced plant sensitivity to bifenthrin. Addition of 12, 15, and 25ppm of bifenthrin reduced the growth of nonmycorrhizal plants but had no effect on the growth of mycorrhizal plants.
Corkidi, L., Evans, M., and Bohn, J. (2008). Infectivity and Effectiveness of arbuscular mycorrhizal fungi in horticultural practices. Combined Proceedings of the International Plant Propagators’ Society 58:67-70.
Corkidi, L., Evans, M. and Bohn, J. (2008). An introduction to propagation of arbuscular mycorrhizal fungi for inoculation of native plant nursery stock. Native Plants Journal 9: 29-38.
Abstract. Arbuscular mycorrhizal (AM) fungi can generally be collected from undisturbed sites and propagated in the nursery following a 7-step process. These fungi form symbiotic associations with most native plants and this relationship provides many benefits to plant health and function in the nursery and on the outplanting site. Although specific techniques vary depending on the fungus, the plant, and the nursery, this introduction should help growers begin their own AM program.
Corkidi, L., Allen, E. B., Merhaut, D., Allen, M. F., Downer, J., Bohn, J., and Evans, M. (2005). Effectiveness of commercial mycorrhizal inoculants on the growth of Liquidambar styraciflua in plant nursery conditions. Journal of Environmental Horticulture 23(2):72-76.
Abstract. The effectiveness of several commercial mycorrhizal inoculants on the growth and development of Liquidambar styraciflua (sweetgum) was evaluated. Plants were grown in a nursery potting mix and were inoculated with the mycorrhizal products at the manufacturer’s recommended rate. The growth response of mycorrhizal and nonmycorrhizal plants was analyzed at two harvests (8 and 14 weeks after transplanting). Significant differences were found in the growth of L. styraciflua to mycorrhizal colonization with the different commercial products. Fourteen weeks after transplanting, inoculation with products 1 (Earth Roots), 2 (MycoApply endo), and 3 (VAM 80) enhanced the growth of sweetgum relative to the nonmycorrhizal plants. However, plants inoculated with products 2 and 3 had greater leaf area, dry mass and relative growth rates than those inoculated with product 1. Plants of L. styraciflua inoculated with product 4 were less responsive to mycorrhizal colonization and only increased their leaf area relative to the non-inoculated controls. Testing both the infectivity and effectiveness of mycorrhizal fungi is recommended for the successful application of mycorrhizal technology in horticultural practices.
Corkidi, L., Allen, E. B., Merhaut, D., Allen, M. F., Downer, J., Bohn, J., and Evans, M. (2004). Assessing the infectivity of commercial mycorrhizal inoculants in plant nursery conditions. Journal of Environmental Horticulture 22(3):149-154.
Abstract. The infectivity of ten commercial mycorrhizal inoculants was examined in nursery conditions. Corn plants were grown in a soil-based medium and in two different soilless substrates, a potting mix prepared with redwood bark, pine sawdust, calcined clay and sand, and the commercial Sunshine # 5 mix, mainly composed of Canadian sphagnum peat moss. The percentage of mycorrhizal colonization obtained with the different mycorrhizal inoculants ranged from 9 to 50%. This variation might reflect the presence or absence of viable propagules, the difference in the recommended rates applied as well as the difference in the content and type of infective propagules of each product. However, the infectivity of each mycorrhizal inoculant was also influenced by the growing media. Two products promoted higher values of mycorrhizal colonization in the Sunshine mix, three in the nursery mix, and one in the soil-based medium. Mycorrhizal colonization did not enhance plant growth. Only the plants inoculated with the products that did not promote mycorrhizal colonization increased their growth relative to the non-inoculated controls, suggesting the presence of other growth promoters in the inoculum products. Based on these results, nurseries should conduct preliminary tests to determine which inoculants will perform in their potting mixes to assure the best fit of inoculum with their particular conditions.