Eleven fungicides were tested in the field, and their effects on Colletotrichum acutatum, the agent of strawberry (Fragaria X ananassa) flower blight,, were examined in vitro. Treatments and doses tested in the field per 100 l of water were iprodione (75 ml), benomyl (100 g), tebuconazole (50 ml), methyl thiofanate (70g), prochloraz (100 ml), propiconazole (50 ml), mancozeb (200 g), folpet (270 g), copper sulfate (200 g) and chlorothalonil (200 g), sprayed weekly (protectants) or bi-weekly (systemic). Fruit yield and number of blighted flowers were computed. For the in vitro fungitoxicity tests, the rate of mycelial growth rate of conidial germination and appressorium formation were studied in fungicide dilutions. In vitro tests were conducted with 1 and 10 ppm, and subsequently at 0.01, 0.1 and 1 ppm for the most efficient products and at 10, 50 and 100 ppm, for the least efficient a.i. The fungicides that resulted in least mycelial growth at the lowest concentrations were prochloraz and tebuconazole, and the ones that least inhibited mycelial growth the was copper sulfate, chlorothalonil and folpet. Most efficient products for inhibition of conidial germination were chlorothalonil, tebuconazole, prochloraz and benomyl. Most efficient products for inhibition of appressorium formation were chlorothalonil and benomyl. Field results were partially different from in vitro results: prochloraz and copper sulfate had the lowest percentages of blighted flowers (53-55%), whereas benomyl had 100% blighted flowers. Although prochloraz, followed by iprodione, folpet and mancozeb resulted in larger fruit yields, no product alone provided sufficient control of strawberry flower blight.
