SYSTEMIC ACQUIRED RESISTANCE AS A STRATEGY FOR DISEASE MANAGEMENT IN ROCKMELON (CUCUMIS MELO VAR. RETICULATUS)

Fungicides are recognized as potential carcinogens and endocrine disrupters and their use is being curtailed or withdrawn. Products which induce natural plant resistance to control disease are recognized as having significant potential to reduce reliance on fungicides. Systemic acquired resistance (SAR) has been intensively investigated for control of field diseases in many crops. However, there are very few reports considering SAR for postharvest disease control. An investigation of SAR and the potential for use in rockmelon postharvest disease control was conducted in this study. In glasshouse and field experiments conducted over 3 years, rockmelon plants were treated with acibenzolar-S-methyl (BTH) (Syngenta, Australia), potassium silicate and a salicylic acid formulation called ReZist (Stoller, Australia) to investigate whether application of these defence elicitors induced resistance to field disease and postharvest disease during storage. Application of all three defence elicitors resulted in increased activities of the pathogenesis related proteins chitinase and peroxidase as well as some physiological responses to disease, indicating that these compounds do elicit defence response in rockmelons. Furthermore postharvest storage diseases were significantly less than the control treatments when rockmelon plants were sprayed preharvest with the elicitors. The results suggest that the defence elicitors investigated here could play an important role in protection of plants from field disease as well as protection of fruit during the postharvest period and have potential for integration into a program of disease control.