Sustainable Management of Soilborne Diseases in Nursery Production
Soilborne diseases reduce plant performance, increase costs to the grower and cause potential ecological damage to the natural environment. The use of Brassicaceae cover crops have not been widely explored and documented in woody ornamental nursery production. The objective of this study was to assess Brassicaceae cover crops as biofumigant for soilborne disease management in nursery production. Inoculation methods and inoculum levels of Rhizoctonia solani was evaluated to determine diseases response. As all three inoculum levels of the agar slurry method showed similar root disease percentages, the lowest inoculum level (1 petri dish/L) was selected for the following experiments. Among the tested fifteen cover crops in the Brassicaceae family, oilseed radish (Raphanus sativus), mustard (Sinapis alba), purple top forage turnip (Brassica rapa), astro arugula (Eruca vesicaria ), mighty mustard® pacific gold (B. juncea ), oriental mustard (B. juncea), dwarf essex rape Brassica (B. napus) and amara mustard green ( B. carinata) showed low root rot disease percentages and diseases incidence in top soil which had pre-existing populations of R. solani or Phytophthora nicotinanae. These selected cover crops were used to perform biofumigation in a greenhouse study and according to observations mustard, purple top forage turnips, astro arugula, mighty mustard, dwarf essex rape, amara mustard and oriental mustard cover crops were effective in controlling R. solani and P. nicotianae pathogens. Similar disease suppression was observed when biofumigation was performed for 1-month or only 14-days. Plants grown in amara mustard, astro arugula and purple top forage turnips amended soils had significantly higher growth and they were selected for the field. A field study was conducted at a collaborator’s nursery where R. solani, Fusarium oxysporum, Phytopythium vexans pathogens were established fungal and oomycetes populations in propogation beds. Kwanzan cuttings were planted two weeks after incorporation of each treatment and plants were evaluated for disease severity on roots. Amara mustard and astro arugula cover crops showed promising results in controlling soilborne pathogens of woody ornamental plants under both greenhouse and field conditions.
Plant sciences|Plant Pathology
Prabha Dhananjani Liyanapathiranage,
"Sustainable Management of Soilborne Diseases in Nursery Production"
ETD Collection for Tennessee State University.