The effect of
synthetic plant growth regulators (PGRs) on Sclerotinia sclerotiorum was
investigated in vitro and in vivo, on plants. The results showed that
naphthalene acetic acid (NAA) has a potential to inhibit fungus in vitro
and in vivo. It reduced white mold disease severity on bean and
cucumber plants at concentrations up to 500, u.g/ml active ingredient.
Ethephon and gibberellic acid (GA3) promoted both mycelium growth rate
and white mold disease severity on plants at concentrations up to 400
/seg/ml. Methyl jasmonate (MeJA), and absiscic acid (ABA) decreased
mycelium growth of the fungus in vitro. MeJA decreased bean and cucumber
white mold disease at concentrations up to 250 /4,g/ml. ABA increased
disease development on bean and cucumber plants at concentrations up to
300 /Lg/Hll. Aminoethoxvinyleglycine (AVG) used as an ethylene-inhibitor
agent significantly inhibited white mold lesions development in vivo
and decreased white mold disease severity on bean and cucumber plants at
concentrations up to 300 /,Lg/ml.
Ethylene was produced by the fungus S. sclerotiorum when grown on
shaking PDB medium amended with 10 mM methionine at a rate of 400
M1/g/h.