Theses and Dissertations at Montana State University (MSU)
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Item Mycofumigation with Muscodor albus : effects on Verticillium wilt and black dot root rot of potato, effects on Glomus intraradices and ectomycorrhizal fungi, and M. albus proliferation in soil(Montana State University - Bozeman, College of Agriculture, 2008) Grimme, Eva; Chairperson, Graduate Committee: Barry J. Jacobsen.Muscodor albus Worapong, Strobel & Hess, isolate CZ-620 (MA) is an endophytic fungus that produces volatile organic compounds (VOCs) and non-volatile antimicrobial compounds. The use of these VOCs to inhibit or kill a wide range of microorganisms is termed mycofumigation. This dissertation focuses on parameters of MA mycofumigation including: production and bioactivity of previously un-described water-soluble antimicrobial compounds produced by MA; distribution of antimicrobial compounds from a MA point source in three soil types as measured by effects on Verticillium dahliae and Colletotrichum coccodes; control of V. dahliae and C. coccodes on potato; the ability of MA to colonize soil; and the effects of mycofumigation on ectomycorrhizal fungi (EMF) in vitro and on the colonization of onion roots by the arbuscular mycorrhizal (AM) fungus Glomus intraradices. The bioactivity of water-soluble compounds produced in potato dextrose broth was significantly increased as measured in growth reduction of C. coccodes, V. dahliae, and Rhizoctonia solani. No reduction was observed for Aphanomyces cochlioides and Pythium ultimum. Antimicrobial compounds from a MA colonized barley point source reduced V. dahliae and C. coccodes populations in soils by 60-100% at distances up to 9 cm from the inoculation source depending on soil type. Mortality rate ranging from 70-100% was observed within a 3 cm radius from the inoculation source. In both field and greenhouse trials, MA colonized barley formulation reduced Verticillium wilt and black dot root rot severity and reduced populations of both pathogens in potato tissue as measured by real-time quantitative PCR and serial dilution. Planting directly into mycofumigated soil previously infested with V. dahliae or C. coccodes resulted in equal control of the pathogens when compared to a one-week mycofumigation period prior to planting. After six weeks of incubation MA did not colonize sterile soil further than 0.5 cm away from a MA inoculation point. In vitro experiments showed that most of the tested EMF were inhibited in the presence of MA VOCs, but were able to resume growth when removed from VOCs. Incorporating MA into soil had no negative but supportive effect on onion root colonization by the AM fungus G. intraradices.Item Effects of mycofumigation using Muscodor albus and Muscodor roseus on diseases of sugar beet and chrysanthemum(Montana State University - Bozeman, College of Agriculture, 2004) Grimme, Eva; Chairperson, Graduate Committee: Barry J. Jacobsen.Methyl bromide-chloropicrin mixtures are the major chemicals used for soil disinfestation in the U.S. These chemicals are highly efficacious fumigants used for preplant soil fumigation in field and greenhouse production. They control soil-borne diseases, insects, nematodes and weeds. The 1996 International agreement to phase-out methyl bromide for soil fumigation will seriously reduce options for controlling soilborne pathogens. Mycofumigation is the use of antimicrobial volatiles produced by fungi such as Muscodor albus and Muscodor roseus for the control of other microorganisms. A synthetic mixture of organic components, which were originally identified in M. albus gases, provided disease control equal to the formulated fungus in terms of reducing damping-off by Aphanomyces cochlioides, Pythium ultimum, and Rhizoctonia solani. The effect of growth substrates for M. albus and M. roseus, their placement and fumigation period on efficacy for control of sugar beet seedling diseases was studied. Optimal growth substrates for M. albus were barley, canola, oat, and stabileze while optimal growth substrates for M. roseus were oat and barley. A 1-week mycofumigation period provided better control of damping-off than direct planting for both Muscodor sp. Mixing substrates with soil was superior to placement in the upper 25 % of the pot in Rhizoctonia-infested soil, whereas placement the in the upper 25 % of the pot was superior in Aphanomyces- and Pythium-infested soil. Field experiments indicate that mycofumigation of Aphanomyces-infested soil, buried 20 and 30 cm deep in field soil, increased seedling establishment of sugar beets. A winter survival study confirmed that M. albus does not survive the winter when buried (0 to 45 cm) in field soil in Montana. Storage of Muscodor sp. stabileze in a starch /sucrose / silica formulation was effective at - 10 °C and 3 to 5 °C for 5 months. In chrysanthemum experiments mycofumigation with M. albus and M. roseus resulted in significantly decreased Verticillium stem colonization compared to the V. dahliae pathogen control.