CSIRO PUBLISHING www.publish.csiro.au/journals/app Australasian Plant Pathology, 2005, 34, 569–575 Protection of grapevine pruning wounds from infection by Eutypa lata using Trichoderma harzianum and Fusarium lateritium S. John A , T. J. Wicks B , J. S. Hunt C , M. F. Lorimer D , H. Oakey D and E. S. Scott A,E A Discipline of Plant and Pest Science, University of Adelaide, Waite Campus, PMB 1, Glen Osmond, SA 5064, Australia. B South Australian Research and Development Institute, GPO Box 397, Adelaide, SA 5001, Australia. C Agrimm Technologies Ltd, PO Box 13-245, Christchurch, New Zealand. D BiometricsSA, University of Adelaide/SARDI, PMB 1, Glen Osmond, SA 5064, Australia. E Corresponding author. Email: eileen.scott@adelaide.edu.au Abstract. Trichoderma harzianum applied to grapevine pruning wounds in a spore suspension and in the commercial formulations of Trichoseal, Trichoseal spray and Vinevax pruning wound dressing reduced recovery of Eutypa lata in the glasshouse and in the field. Recovery of E. lata was significantly reduced (P < 0.001) when fresh wounds were treated with viable T. harzianum 2 or 7 days before inoculation with ascospores of the pathogen in the glasshouse. In field experiments, recovery of E. lata was significantly reduced (P < 0.001) when fresh pruning wounds were treated with spores of T. harzianum, Fusarium lateritium or Vinevax 1 or 14 days before ascospores were applied. In general, a delay of 14 days between wounding and inoculation with ascospores of E. lata reduced recovery of the pathogen compared with inoculation on the day after wounding. Additional keywords: biological control, fungal antagonists, grapevine trunk disease. Introduction Eutypa dieback is a lethal disease affecting mature vines and is caused by the ascomycetous fungus Eutypa lata (syn. Eutypa armeniacae) (Moller and Kasimatis 1978). Ascospores of E. lata land on fresh wounds in woody tissue and the fungus grows slowly in the wood. Symptoms of dieback might appear several years after inoculation. Significant yield losses are caused by eutypa dieback in grape-growing areas throughout the world (Carter 1991). Wicks and Hall (1997) suggest that in Australia up to 60% of the vines might be affected in certain old, elite vineyards. Prevention of infection by treatment of large wounds with fungicides or wound sealants is the preferred method of control (Moller and Kasimatis 1978; Moller and Kasimatis 1981). Eradicative sanitation is not always successful because of the broad host range of the pathogen (Carter 1991). Although benomyl is effective against E. lata (Munkvold and Marois 1993b), Benlate or other benzimidazole fungicides were not registered in Australia as grapevine wound protectants. Benlate is no longer commercially available and research on alternative chemicals for wound protection is in progress (Sosnowski et al. 2004). Biological control agents that colonise pruning wounds offer long-term protection from infection by E. lata. Biological control of E. lata on apricot trees has been demonstrated by treating pruning wounds with macroconidia of Fusarium lateritium (Carter 1971; Carter and Price 1974, 1975), but this fungus has not been developed into a commercial product. Rolshausen and Gubler (2005) found Cladosporium herbarum in combination with boric acid to reduce the incidence of infection of pruning wounds on grapevine by E. lata in California. Trichoprotection products, containing seven strains of Trichoderma harzianum, are registered in New Zealand for protection of grapevines from eutypa dieback and of stone fruit trees from silver leaf (Chondrostereum purpureum). Three of these strains of T. harzianum were shown to inhibit E. lata in vitro by antibiosis, and recovery of E. lata from autoclaved cane segments that were co-inoculated with spores of T. harzianum and E. lata was reduced by 90% (John et al. 2004). Subsequent experiments carried out in the glasshouse and field to assess the efficacy of T. harzianum as a grapevine wound protectant are reported here. © Australasian Plant Pathology Society 2005 10.1071/AP05075 0815-3191/05/040569