CONSTRAINTS TO THE DEVELOPMENT OF BIOFUNGICIDES - THE EXAMPLE OF AQ10, A NEW PRODUCT FOR CONTROLLING POWDERY MILDEWS

Over recent years, the company ECOGEN Inc. has been successfully devel oping a biofungicide known under the trade name 'AQ10' in the USA wher e it has been authorized in 1994 for controlling powdery mildews on va rious host plants. This new product is based on the use of Ampelomyces quisqualis, an hyperparasitic fungal species infesting representative s of Erysiphaceae (powdery mildews) only. The production process now a llows for the hyperparasite to be mass-cultured and formulated into an easily water-dispersed, dry powder which preserves spore viability at room temperature for a period in excess of 12 months. Upon spraying, the conidia germinate rapidly to effectively attack any developing pow dery mildew colonies. Efforts are now concentrating on experimental ap plication schedules in vineyards aimed at defining an optimal position ing of the biofungicide within existing disease control programmes. Th e pilot trials are being conducted over a large number of wine-produci ng areas under a Mediterranean climate around the world where powdery mildew represents the major pest problem. Results obtained so far show that in order to achieve an optimal, cost-effective, consistent disea se control, the biofungicide has to be applied before the incidence of powdery mildew has reached high levels, and at any of the three most susceptible growth stages of grapevine, i.e. bud break, between flower ing and bunch closure, and just before veraison. The biofungicide may therefore be used as a curative to slightly preventative control agent likely to fit into any IPM strategies. The various technical problems associated with the development and industrial production of this new biofungicide are largely solved. Constraints relating to designing co mprehensive, user-friendly IPM programmes which. include 'AQ10' still require adjustments in terms of defining spraying dates and intervals according to a range of agricultural practices, climatic changes likel y to occur during the season, and compatibility for tank-mixing with o ther pesticides. A number of additional constraints relate to official registration in various countries, distributors' and farmers' accepta nce of a new, 'living' product: these are still more difficult to addr ess because they claim for a profound change in the users' general att itude towards controlling diseases of cultivated plants.