EFFECTIVENESS OF CONIDIA OF TRICHODERMA-HARZIANUM PRODUCED BY LIQUID FERMENTATION AGAINST BOTRYTIS BUNCH ROT OF TABLE GRAPE IN CHILE

Over 100 isolates of Trichoderma harzianum Rifai were obtained from so il samples and from the phylloplane of kiwifruit (Actinidia chinensis Planchon), grape (Vitis vinifera), orange (Citrus sinensis (L.) Osbeck ), eucalyptus (Eucalyptus globulus Labill.), and apricot (Prunus armen iaca L.) in Chile. A subsample of 48 isolates were tested and found to be antagonistic to Botrytis cinerea Pers. ex Fr. on apple fruits. Iso late S10B from soil in Chile provided similar control of Botrytis bunc h rot under field conditions to reference isolate P1 (ATCC 74058) and T39 (Trichodex 25 WP). However, field trials conducted during four gro wing seasons (1992-1995) with preparations of conidia of formulated or non-formulated T. harzianum P1 provided only partial control of Botry tis bunch rot of 'Thomson Seedless' table grape. Disease incidence was significantly different (p < 0.05) from untreated controls, but equal to or less than the control achieved with vinclozolin (Ronilan 50 WP, 1.5 kg ha(-1)) and similar to captan (Captan 80 WP, 4 kg ha(-1)). Thi s level of control is insufficient considering that tolerance for B. c inerea is very low (< 0.5%) on table grapes. Nevertheless, the antagon istic activity of T. harzianum may be effective if it is integrated wi th other control practices, and may result in acceptable levels of dis ease control with reduced levels of pesticide use. (C) 1997 Elsevier S cience Ltd.