Effects of Tween 80 on Three Different Powder Formulations of Penicillium oxalicum, a Biocontrol Agent of Tomato Wilt

摘要

Penicillium oxalicum is a biocontrol agent against F. oxysporum f. sp. lycopersici, the causal agent of tomato wilt. Conidia of P. oxalicum produced in a solid-state fermentation system and dried by fluid-bed drying had 50 % viability after 180 days of storage at room temperature and were effective in reducing the incidence of fusarium wilt. Dry conidia are very hydrophobic and are difficult to suspend in water. Tween 80 (1 %), a detergent, was used to improve the production of conidia in solid-statefermentation, their viability during storage and dispersion in water. Tween 80 was added in three steps of the fermentation and drying process to get different formulations: i) in mixture with the fermentation substrate, ii) to conidia before drying, and iii) to conidia after drying. Production of conidia in substrate mixed with Tween 80 was 67 % higher than without detergent. Tween 80 added to conidia after drying enhanced dispersal and hydration of conidia and avoided osmotic shock. After one year, conidia fermented with Tween 80 are more stable than those fermented without Tween 80 at room temperature. A conidia] formulation with Tween 80 significantly reduced tomato wilt under glasshouse and field conditions. Results indicate that addition of Tween 80 to conidia unproved P. oxalicum formulation.