title: Measuring root disease suppression in response to a compost water extract.
abstract: Commercial application of compost to prevent plant disease is hindered by variable performance. Here, we describe the use of a growth pouch assay to measure impact of a compost water extract (CWE) on root infection under controlled conditions. Most pea roots (≥95%) inoculated with Fusarium solani or Phoma pinodella spores rapidly develop a single local lesion in the region of elongation. In the presence of CWE, infection of pea roots grown in pouches was reduced by 93 to 100%. CWE used as a drench on pea seedlings grown in sand also resulted in 100% protection but, in a heavy clay soil, infection was reduced by <50%. CWE filtered to remove microorganisms did not inhibit frequency of F. solani infection, and resulted in increased local lesion development on individual roots. CWE inhibited mycelial growth of both pea- and cucumber-infecting isolates of F. solani in culture but exerted <40% protection against cucumber root infection. CWE treatment of pea but not cucumber was associated with retention of a sheath of border cells interspersed with bacteria covering the region of elongation. Growth pouch assays may provide a system to monitor effects of specific compost mixtures on root-rhizosphere interactions, and to identify variables influencing disease control.
authors: Soil, Water and Environmental Sciences Department, University of Arizona, AZ, USA.
authors: Gilberto
authors: G
authors: Curlango-Rivera
authors: Tom
authors: T
authors: Pew
authors: Hans D
authors: HD
authors: VanEtten
authors: Xiong
authors: X
authors: Zhongguo
authors: Naitong
authors: N
authors: Yu
authors: Martha C
authors: MC
authors: Hawes
mesh_terms: D001203:Ascomycota / Q000254:growth & development / Q000472:pathogenicity; D018556:Crops, Agricultural; D018553:Cucumis sativus / Q000276:immunology* / Q000382:microbiology / Q000502:physiology; D004198:Disease Susceptibility; D005670:Fusarium / Q000254:growth & development / Q000472:pathogenicity*; D018532:Pisum sativum / Q000276:immunology* / Q000382:microbiology / Q000502:physiology; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018517:Plant Roots / Q000276:immunology* / Q000382:microbiology / Q000502:physiology; D036226:Seedlings / Q000276:immunology / Q000382:microbiology / Q000502:physiology; D012987:Soil / Q000737:chemistry; D014867:Water
chemical_list: D012987:Soil; D014867:Water