Abstract

                                Thirty wheat (Triticum aestivum L.) seed samples were collected from different wheat growing areas of Tamil Nadu. The pathogen Fusarium graminearum Schwabe recorded the maximum seed-borne incidence (38.6%) in Wellington wheat seed sample. The Trichoderma harzianum and Pseudomonas fluorescens (Pf1) exhibited high level of inhibition of 65.83 and 62.22 per cent over control against F. graminearum under in vitro condition respectively. Among the 46 plant extracts, zimmu leaf extract recorded minimum (15%) germination of F. graminearum acroconidia under in vitro condition. Application of Zimmu leaf extract 0.2 per cent sprayed during anthesis stage effectively controlled the seed-borne F. graminearum spread under glass house condition. Zimmu leaf extract, zimmu leaf extract + T. harzianum, zimmu leaf extract + P. fluorescens and zimmu leaf extract + T. harzianum + P. fluorescens spray treatments were on par with each other to record the least incidence of 15.60 to 17.25 per cent Fusarium head scab in field conditions. Among the eight treatments, zimmu leaf extract sprayed alone and combined with antagonists, decreased seed borne incidence and increases grain yield in wheat.

Key words : Fusarium graminearum, Pseudomomas, Trichoderma, Zimmu leaf extract