Effects of inoculations with pathogenic and beneficial microorganisms and ammonium of nitrate fertilization on Easter lily growth

Graduation date: 1991Although chemical fungicides are commonly used to control fungal soil-borne\ud diseases of Easter lilies, Lilium longiflorum Thunb., in field production and\ud greenhouse forcing, cultural and biological controls may be alternatives or\ud complementary to chemicals for control of pathogens.\ud The influence of inoculations with beneficial, symbiotic, and biocontrol\ud microorganisms to enhance growth of Easter lilies has not been extensively\ud investigated. In this research, the effects and interactions of fungal and bacterial\ud biocontrol microorganisms or chemical fungicide, mycorrhizae, and ammonium or\ud nitrate fertilization on growth and pathogens of Easter lily were evaluated over a\ud two year period.\ud Inoculation with Glomus intraradices Schenck & Smith, increased fresh\ud weight of stem and basal roots two-fold by the end of the first growing season.\ud Increased root growth was associated with less "root rot complex" and decreased\ud pathogen disease severity on plants that were inoculated with both mycorrhizal\ud fungi and pathogens when planted for forcing. Rhizoctonia solani Kuhn infection\ud was decreased by mycorrhizal inoculation. However, bulb infection by Fusarium\ud oxysporum f.sp. lilii Snyd & Hans was increased when mycorrhizal and pathogen\ud inocula were added simultaneously. At the end of the second growing season,\ud shoot and bulb fresh weights of mycorrhizal-inoculated plants were 14% greater\ud than plants not inoculated with the mycorrhizal fungus.\ud Pathogen control treatment and nitrogen form interacted to affect plant\ud growth. Inoculation with the bacterial biocontrol agent Enterobacter cloacae\ud (Jordan) Hormaeche & Edwards in combination with nitrate fertilizer resulted in\ud taller plants with greater number of flowers. Least height, fewest lower dead\ud leaves, and fewest flowers occurred on plants in the treatment combination of\ud Banrot fungicide and ammonium fertilization. The combination of the fungal\ud biocontrol agent Trichoderma harzianum Rifai with nitrate form of nitrogen, and\ud the bacterium Bacillus subtilis (Ehrenberg) Cohn with ammonium-N increased\ud stem root fresh weight. Trichoderma harzianum and E. cloacae treated plants had\ud 67% greater growth of stem roots and basal roots.\ud Disease control and growth of Easter lily were equal or greater when\ud beneficial microorganisms were substituted for Banrot fungicide treatment.\ud [Chemical name used: {5-Ethoxy-3-trichloromethyl-l,2,4-thiadiazole and dimethyl\ud 4,4-o-phenylenebis (3-thioallophanate)} (Banrot)]