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Poster: Biology & Disease Mgmt: Biological Control


Trichoderma asperellum survival and parasitism of Sclerotinia sclerotiorum sclerotia in different soil types
M. LOBO (1), A. Geraldine (2), F. Yoshida (3), E. Civardi (3), E. Barbosa (1) (1) Embrapa (Brazilian Agricultural Research Corporation), National Center for Rice and Beans Research, Brazil; (2) Instituto Federal Goiano, Brazil; (3) Universidade Federal de

Effectiveness of bioagent Trichoderma asperellum is influenced by physical, chemical, biological and environmental factors, but there is no clear idea of how such variables affect antagonist endurance. This study assessed the survival of T. asperellum and the parasitism of Sclerotinia sclerotiorum sclerotia in different Brazilian soils. The test was carried out in a completely randomized design, arranged in a 4 x 6 factorial schedule with five repetitions. Experimental factors comprised six soils of distinct texture and fertility profiles, and four biocontrol treatments with three T. asperellum isolates and a water control. Plots consisted of 12cm x 22cm x 3cm transparent plastic containers, with sclerotia distributed over 300g of soil. After spraying with 2.0 x 1012 T. asperellum conidia ha-1 and soil moisture adjusted to 100% field capacity, treatments were incubated at 20ÂșC with 12h photoperiod for 28 days. Weakly assessments considered sclerotia parasitism, area under antagonist survival curve (AUASC), culturable fungi and bacteria, and bacterial diversity estimated with Biolog Ecoplates. Principal component analysis showed that parasitism of S. sclerotiorum sclerotia was proportional to T. asperellum AUASC. In contrast, antagonist survival was negatively affected by soil pH, bacterial density and diversity, organic matter, Ca, Mg and K contents. Biocontrol efficiency varied according to soil source.