The Integrated Control of Armillaria mellea 1. Glasshouse Experiments

ABSTRACT

Several isolates of Trichoderma harzianum, T. viride and T. hamatum, an isolate each of Dactylium dendroides, Chaetomium olivaceum and some other fungi found to be antagonistic in vitro against several isolates of the root rot pathogen, Armillaria mellea, were evaluated for their ability to suppress root rot of potted strawberry plants in the glasshouse. Some of these antagonists were selected for integration with two systemic fungicides, fosetyl-Al and fenpropidin, in the glasshouse. A significant interaction was found between the antagonists, fungicides and their sequence of application. T. harzianum isolates Th2 and Th23 showed sensitivity to direct application of fenpropidin but not to fosetyl-Al. The antagonists were generally more effective when applied with a time interval of 40 days after fenpropidin or before fosetyl-Al. Integration of Th2 and fenpropidin was the most effective treatment and resulted in the survival of 75% of strawberry plants up to the end of the experiment lasting 566 days when the fungicide was applied first; no plant survived that long when the sequence of application was reversed. High concentrations of fenpropidin, but not of fosetyl-Al, were phytotoxic to the strawberry plants. Fosetyl-Al was also significantly (p < 0.05) more effective than fenpropidin in enhancing the survival of the strawberry plants.