Browsing by Author "SanMartin, R"

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    Biological and integrated control of Botrytis bunch rot of grape using Trichoderma spp.
    (1996) Harman, GE; Latorre, B; Agosin, E; SanMartin, R; Riegel, DG; Nielsen, PA; Tronsmo, A; Pearson, RC
    Field trials were carried out in upstate New York in 1990, 1992, 1998, and 1994 and in Chile in 1992-1993 and 1993-1994 in order to evaluate the ability of various strains of Trichoderma spp. to control bunch rot of grape, to assess the compatibility and possible additive effects of selected biocontrol fungi and dicarboximide fungicides, and to determine factors affecting biocontrol efficacy. In 1990, three strains of Trichoderma spp. were evaluated for their biocontrol ability, and all provided significant control of Botrytis cinerea. As few as two late applications of the biocontrol fungi were nearly as effective as up to five applications throughout bloom and fruit development. Trials in New York in 1992 and in Chile in 1992-1993 indicated that Trichoderma harzianum could replace some applications of iprodione or vinclozolin with little reduction in efficacy. In New York in 1993, we found that applications of T. harzianum at bloom and early fruit development followed by a tank-mix application of T. harzianum and half rates of iprodione gave extremely effective control of bunch rot. In 1994, less effective control was obtained than in earlier years. Addition of a nutritive adhesive (Pelgel, a mixture of carboxymethyl cellulose and gum arabic) applied with the biocontrol agent tended to improve results. Thus, biological control of bunch rot of grape with T. harzianum can be an effective method of management of this disease. (C) 1996 Academic Press, Inc.
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    Effect of culture conditions on spore shelf life of the biocontrol agent Trichoderma harzianum
    (1997) Agosin, E; Volpe, D; Munoz, G; SanMartin, R; Crawford, A
    The influence of pH, carbon:nitrogen (C:N) ratio, carbon content and harvesting time on spore attributes of the biocontrol agent Trichoderma harzianum was evaluated. The effect of these culture parameters on viability, shelf-life and ultrastucture was also assessed. pH was a key parameter to manipulate for both growth and sporulation, while carbon concentration and C:N ratio strongly affected spore production time. At fixed pH, the C:N ratio had a limited influence on production yield, but was critical for spore shelf-life. The highest spore longevity was found in a medium with a C:N ratio of 14 and a pH of 7.0, when most resulting spores were still alive after 45 d storage. These spores also remained viable during storage under a broad range of relative humidities, indicating that they would be more sustainable in the field.
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    Effectiveness of conidia of Trichoderma harzianum produced by liquid fermentation against Botrytis bunch rot of table grape in Chile
    (ELSEVIER SCI LTD, 1997) Latorre, BA; Agosin, E; SanMartin, R; Vasquez, GS
    Over 100 isolates of Trichoderma harzianum Rifai were obtained from soil 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 armeniaca L.) in Chile. A subsample of 48 isolates were tested and found to be antagonistic to Botrytis cinerea Pers. ex Fr. on apple fruits. Isolate S10B from soil in Chile provided similar control of Botrytis bunch rot under field conditions to reference isolate P1 (ATCC 74058) and T39 (Trichodex 25 WP). However, field trials conducted during four growing seasons (1992-1995) with preparations of conidia of formulated or non-formulated T. harzianum P1 provided only partial control of Botrytis 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)). This level of control is insufficient considering that tolerance for B. cinerea is very low (< 0.5%) on table grapes. Nevertheless, the antagonistic activity of T. harzianum may be effective if it is integrated with other control practices, and may result in acceptable levels of disease control with reduced levels of pesticide use. (C) 1997 Elsevier Science Ltd.
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    Induction of trehalose in spores of the biocontrol agent Trichoderma harazianum
    (1997) Pedreschi, F; Aguilera, JM; Agosin, E; SanMartin, R
    Spores of the biocontrol agent Trichoderma harzianum P1 produced in liquid media and harvested in the stationary sporulation stage SSS (after 60 h), had higher viability after slow (>4x) and fast drying (>12x) than their counterparts harvested in the exponential sporulation stage, ESS (after 30 h). The trehalose content of SSS spores was almost 20x higher than that of ESS spores (0.16 vs. 3.4 mg/100 mg, respectively). Heat shock (40 degrees C x 90 min) effectively increased the trehalose content 2.5x with respect to untreated SSS spores. The trehalose content achieved in heat-treated SSS spores was almost 60% higher than the maximum reached by holding the spores under water-stress at 97% relative humidity prior to drying.