The object of the project was to develop biological means of control of fungal foliar diseases as an alternative to chemical means and concentrated on selected plant diseases of high economic significance. Biological control agents using Acremorium alernatum, Penicillium species and various microorganisms were successfully applied against Botrytis cinerea. However, their success in practical applications, depends on their performance under variable (micro) climatic conditions. An extract from 2 month old horse manure compost was found to be highly efficient against Botrytis on detached grape vine leaves. Botrytis on grape berries was also reduced in field experiments. Grey mould control in strawberries (in Bonn, Germany) showed promising results. A simple bioassay, using detached leaves, was also used to study the effect of compost extracts and infection of bean leaves by ascospores of Sclerotinia sclerotiorum. A commerically produced compost, of consistent quality and a high number of antagonists, was found which was used to produce watery compost extracts for field testing. Suppression of the following host pathogen systems was successful: Botrytis cinerea on grape vine and strawberries; and Plasmopara vitocola, Sphaeroteca species and Uncicula species on grape vine.
Fungal foliar diseases cause heavy losses in many crop plants in all climatic zones of Europe. Their regular control by fungicide sprays is an important cost factor for farmers, which results in problems of toxic residues on food products, and contaminates the environment. Within the Member States of the Community there is a wide spread interest to reduce the application of chemical pesticides by volume and frequency and replace them by biological control methods, as far as possible.
The project concentrates on selected plant diseases of high economic significance, such as potato leaf blight, grape powdery mildew and Botrytis-grey mold of vegetable corps in greenhouses and outdoors. Their biological control is based on the application of selected micro- organisms and of complex substrates like watery extracts of composted organic materials. The biocontrol agents are tested under various climatic environments like the Greek island of Crete, Southern Portugal, England, Holland and Germany. Detailed studies will help to optimize the production of the control agents and their application. Their mechanisms of action through competition for nutrients on plant surfaces, antibiosis, hyperparasitism or induced resistance of the crop plants will be further explored. Practical application of the developed methology is expected to occur widely in all certified "organic" land use systems, but will also be available for "conventional" growers, left without effective chemical pesticides due to le al or other restrictions.
CV35 9EF Warwick