Preservation, mass production and storage of Stagonospora convolvuli, a bioherbicide candidate for field bindweed (Convolvulus arvensis)

Different solid substrates were investigated as spore production methods fo r Stagonospora convolvuli strain LA39, a potential bioherbicide for field b indweed (Convolvulus arvensis L.). Up to 4 x 10(8) spores/g of substrate we re yielded on cous-cous (cracked hard wheat). The spores were as pathogenic as those grown on artificial medium (V-8-juice agar). The air-drying on ka olin and storage at 3 degrees C kept spores viable and pathogenic for 180 d ays. Spore germination exceeded 70% for the first 140 days and then decline d to 50% after 175 days. Less than 5% of spores were still viable after 17 months. The preservation of stock cultures in 10% glycerine at -80 degrees C and in liquid nitrogen did not affect viability or pathogenicity of the s pores.