Improving Nursery Crop Production Using Sustainable Approaches for Disease Management
Phytophthora root rot caused by Phytophthora nicotianae was major limitation faced by nursery growers in Buxus sempervirens. Treatments that effectively reduced Phytophthora root rot in boxwood were pyraclostrobin, ametoctradin + dimethomorph, and oxathiapiprolin in greenhouse and pyraclostrobin, oxathiapiprolin, mefenoxam, fluzapyroxad and combination nitrogen, potash, and Trichoderma spp. in field. Biofumigants such as yellow mustard, mighty mustard, amara mustard, oriental mustard and arugula lowered Phytophthora disease severity and pathogen recovery. In commercial nurseries, lowered disease severity and pathogen recovery were observed from biofumigated soil with natural P. nicotianae presence and reintroduction of the pathogen. Colony count was higher for Pseudomonas and lower for Fusarium and Rhizoctonia in biofumigated soil compared to the non-biofumigated soil in all experiments. Root and crown rot of oakleaf hydrangea were observed as a problem in some Tennessee nurseries. Fusarium oxysporum was identified as causal organism based on morphological and molecular analysis. Treatments that effectively reduced Fusarium root rot were mefentrifluconazole, the low rate (1.09 mL/L) of difenoconazole + pydiflumetofen, and the high rate (1.32 mL/L) of isofetamid and the high rate (1.64 g/L) of ningnanmycin. Fifteen different hydrangea cultivars were tested to determine the resistance against F. oxysporum. Root rot severity, pathogen recovery, fusaric acid and mannitol concentration were assessed from roots. Results indicate no cultivars were resistant to F. oxysporum. Cultivars from H. arborescens, H. macrophylla and H. paniculata were less susceptible compared to cultivars from H. quercifolia. Among H. quercifolia, cultivars Snowflake, John Wayne and Alice were less susceptible.
Plant sciences|Plant Pathology|Horticulture
"Improving Nursery Crop Production Using Sustainable Approaches for Disease Management"
ETD Collection for Tennessee State University.