title: Effect of temperature and water activity on spore germination and mycelial growth of three fungal biocontrol agents against water hyacinth (Eichhornia crassipes).
abstract: OBJECTIVE
  To determine the effect of water activity (a(w) =0·880-0·960) and temperature (15-35°C) on the percentage of viable conidia and mycelial growth of three biocontrol agents effective against water hyacinth in Mali: Alternaria sp. isolate Mlb684, Fusarium sacchari isolate Mln799 and Cadophora malorum isolate Mln715.
  
  
  RESULTS
  The fungi were grown in vitro on plates containing potato dextrose agar medium at different a(w) values (glycerol being added to adjust the a(w)). The percentage of viable conidia and radial growth rate decreased with decreasing water activity. Statistical analysis showed a significant effect of a(w), temperature and the a(w) × temperature interaction on mycelial growth (P<0·0001). Water activity emerged as the factor exerting the greatest influence. Differences were observed between the fungi tested, the C. malorum appearing more tolerant to low a(w) and the F. sacchari more tolerant to high temperature (35°C). Growth models predicting the combined effect of a(w) and temperature were developed and response surfaces generated, showing fairly good agreement with the experimental values.
  
  
  CONCLUSIONS
  Our results confirm the previous finding that a(w) has a greater influence than temperature on fungal growth. Under most conditions, variation of environmental factors has a detrimental influence on the percentage of viable conidia and mycelial growth rate of fungal isolates.
  
  
  CONCLUSIONS
  The developed models may contribute to predicting the best environmental conditions for use of these fungi as effective biocontrol agents against water hyacinth.
authors.affiliation: Unité de Phytopathologie, Gembloux Agro-Bio Tech, Université de Liège, Gembloux, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Dagno
authors.forename: R
authors.initials: R
authors.lastname: Lahlali
authors.forename: M
authors.initials: M
authors.lastname: Diourté
authors.forename: M H
authors.initials: MH
authors.lastname: Jijakli
mesh_terms: D000528:Alternaria / Q000254:growth & development / Q000302:isolation & purification; D001203:Ascomycota / Q000254:growth & development / Q000302:isolation & purification; D031806:Eichhornia; D004777:Environment; D005658:Fungi / Q000254:growth & development*; D005670:Fusarium / Q000254:growth & development / Q000302:isolation & purification; D008302:Mali; D008954:Models, Biological; D025282:Mycelium / Q000254:growth & development; D013172:Spores, Fungal / Q000254:growth & development; D013696:Temperature; D014867:Water
chemical_list: D014867:Water