EFFECTS OF COMBINED METHYL JASMONATE AND ETHYLENE-INHIBITOR TREATMENTS AGAINST BOTRYTIS CINEREA INFECTING GERALDTON WAXFLOWER

Abstract

Infections by Botrytis cinerea cause ethylene-mediated flower fall in cut Geraldton waxflower (Chamelaucium uncinatum). Methyl jasmonate (MJ) is a known host plant defence elicitor, and MJ treatments have demonstrated potential to suppress Botrytis on waxflower. However, MJ can also induce waxflower flower abscission. Flower fall in waxflower can be prevented by treatments with anti-ethylene agents. Pot and field experiments were conducted to determine if combining MJ and anti-ethylene treatments could suppress Botrytis and prevent flower fall. Waxflower 'My Sweet Sixteen' plants were spray-treated pre- and postharvest with MJ (1000 mu M), treated postharvest with either 1-methylcyclopropene (MCP fumigation; 0.08 mu l L-1) or silver thiosulphate (STS pulse; 0.5 mM), and then challenged with Botrytis. Pre- and postharvest MJ treatments reduced Botrytis development, but increased flower fall. In combination with MJ treatment, MCP treatment did not reduce either Botrytis disease or flower fall. MJ in combination with STS reduced (P < 0.05) disease severity for up to 6 days on sprigs harvested from pot-grown plants. However, this combination tended to increase Botrytis disease severity on sprigs from field-grown plants 6 days after inoculation. This inconsistency between pot- and field-grown plants suggests an overriding influence of environment and/or plant management on inducible host defence.