Biocontrol of root and crown rot in tomatoes under greenhouse conditions using Trichoderma harzianum and Paenibacillus lentimorbus. Additional effect of solarization

Indexación: ScieloTrichoderma harzianum 650 (Th650) and Paenebacillus lentimorbus 629 (Pl629) selected earlier for their ability to control Rhizoctonia solani, Fusarium solani and F. oxysporum in vitro, were applied alone or combined with solarization (summer assay) and/or with methyl bromide (MeBr) (summer and winter assays) to a soil with a high inoculum level, for the control of tomato root rot caused by the complex F. oxysporum f. sp. lycopersici - Pyrenochaeta lycopersici - Rhizoctonia solani. Evaluations were also performed independently for root damage caused by P. lycopersici, and also for R. solani in the summer assay. MeBr decreased tomato root damage caused by the complex from 88.7% to 21.2% and from 78.4% to 35.7% in the summer and in the winter assay, respectively. None of the bio-controllers could replace MeBr in the winter assay, but Th650 and Pl629 reduced root damage caused by this complex in the summer assay. Treatments with bio-controllers were improved by their combination with solarization in this season. Independent evaluations showed that the positive control of Th650 towards R. solani and the lack of effect on P. lycopersici correlates well with the endochitinase pattern expressed by Th650 in response to these phytopathogens. Root damage caused by R. solani can be controlled at a similar level as it does MeBr in summer assays, thus representing an alternative to the use of this chemical fungicide for the control of this phytopathogen.Financial support: Fondecyt 1990785

Notes about chilean uredinales. VI: uromyces traucoensis sp. Nov. On seillera radicans cav. (goodeniaceae) and its distribution area.

Se describen las características de una nueva especie de Uredinal autoico y macrocíclico sobre Selliera radicans Cav. (Goodeniaceae) en Chile, al que se le denominó Uromyces traucoensis, estableciéndose semejanzas y diferencias con otras especies de Uromyces que atacan este hospedero en Australia y Nueva Zelandia.Se comenta la dispersión del hospedero y de las tres especies de Uromyces, correlacionándola con otros casos semejantes, tales como Uredinales que atacan coníferas, el género Cyttaria sobre Nothofagus y el caso de similitud extremadamente coincidente del mismo biotipo de Uromyces minor sobre Trifolium dubium en Chile y Nueva Zelandia

Controle da podridão cinzenta da maçã por produtos naturais biologicamente ativos

Indexación: Web of Science; ScieloBiorend SC (chitosan), BC-1000 EC (grapefruit extract plus bioflavonoids) and ECO-100 SC (bioflavonoids plus organic acids, citric phytoalexins, fatty acids, glycerides and sugars), respectively, suppressed grey rot of apple caused by B. cinerea by 80.1%, 79.0% and 76.5% when used as post-harvest treatments under controlled conditions. When applied as combined pre- and post-harvest treatments Biorend SC inhibited fruit rot by 49.9 %, while BC-1000 EC and ECO-100 SC were ineffective. None of the products inhibited fruit rot when applied as pre-harvest treatments under controlled conditions or as post-harvest treatments under commercial conditions. The algal polysaccharide ulvan used in post-harvest treatments suppressed grey rot by 56.0% under controlled conditions, but had no inhibitory effect on combined pre- and post-harvest treatments. The inability of products to activate defense mechanisms (chitinase and peroxidase) of fruits was consistent with the unsuccessful control of rot by pre-harvest treatment. The results suggest that the natural products used have potential for use in integrated management of Botrytis rot when applied after harvest.Biorend SC (quitosana), BC-1000 EC (extrato de toranja mais flavonóides), e ECO-100 SC (bioflavonóides mais ácidos orgânicos, fitoalexinas cítricas, ácidos graxos glicerídeos e açúcares) inibiram em 80,1%, 79,0% e 76,5%, respectivamente, a podridão causada por Botrytis cinerea quando utilizados no tratamento pós-colheita de frutos de maçã sob condições controladas.Tratamento combinado de Biorend SC, com aplicação tanto em pré como no pós-colheita, proporcionou 49,9% de inibição da podridão, enquanto BC-1000 e ECO-100 EC não foram efetivos. Nenhum desses produtos inibiu a podridão cinzenta, quando utilizados em tratamento de pré-colheita em condições controladas ou em tratamento de pós-colheita em condições comerciais. O polissacarídeo algal ulvana, utilizado nos tratamentos de pós-colheita, reduziu em 56% a podridão cinzenta das maçãs em condições controladas, mas não teve efeito inibitório nos tratamentos combinados de pré e pós-colheita. A incapacidade dos produtos em ativar mecanismos de defesa (quitinases e peroxidases) nos frutos, após o tratamento em pré-colheita, foi consistente com a falta de controle da podridão nesse tipo de ensaio. Pelos resultados, sugere-se que os produtos naturais utilizados apresentam potencial para a utilização no manejo integrado da podridão de Botrytis quando aplicados em pós-colheita.http://ref.scielo.org/kcxb9

New strains obtained after UV treatment and protoplast fusion of native Trichoderma harzianum: their biocontrol activity on Pyrenochaeta lycopersici

Indexación: ScieloThe obtainment of 30 new strains from native Trichoderma harzianum after UV light irradiation (UV-A and UV-C), and of 82 strains resulted from protoplast fusion were accomplished. The new strains, initially selected for their growing rate under low temperature and high pH conditions, as well as for their innocuousness on tomato plants, were tested for in vitro inhibition of Pyrenochaeta lycopersici in dual cultures and due to secretion of volatile and diffusible metabolites. All the UV-A and UV-C selected candidate mutants were innocuous to tomato plants, but none of them showed improvement in their biocontrol activity on P. lycopersici. Th12A20.1 increased 1.3 and 1.9 fold the total fresh weight of Fortaleza tomato plants when compared to its parental strains Th12 and Th11, respectively. The selected candidate mutants obtained through protoplast fusion were also innocuous to tomato plants, but only ThF1-2 and ThF4-4 inhibited 1.3 fold (in dual cultures) and 5 fold (due to secretion of volatile metabolites) the growth of P. lycopersici, respectively, in relation to the mean inhibitory effect of both parents. Therefore, these candidate mutants could be included in experiments under field conditions

The effect of electrolyzed water on phytopathogenic fungi that infect Prunus persica var. nectarine at post-harvest / Efecto del agua electrolizada en fitopatógenos fungosos que afectan Prunus persica var. nectarine en postcosecha

Postharvest immersion of Prunus persica var. nectarine into electrolyzed water, EW (25.2 ppm of active ingredient), at different time periods of inoculation with pathogens previously isolated from rotted fruits (A, immediately before fruit immersion; B, three hours after fruit immersion and C, three hours before fruit immersion), significantly reduced fruit rotting caused by Botrytis cinerea (A: 40.2%, B: 43.1% and C: 39.1%), or by Monilinia laxa (A: 80.9%, B: 49.8% and C: 46.2%), or by Penicillium. expansum (A: 60.3%, B: 31.9% and C: 49.7%) or by Rhizopus stolonifer (A: 74.4%, B: 60.8% and C: 72.6%). Immersion of fruits into NaClO (100 ppm of active ingredient), showed significant differences with EW treatment: B. cinerea (B/NaClO: 34.5%), M. laxa (A/NaClO: 62.2%; B/NaClO: 36.2% and C/NaClO: 36.2%); P. expansum (C/NaClO: 60.9%) and R. stolonifer (A/NaClO: 81.3%; B/NaClO: 71,2% and C/NaClO: 83.9%) being in most cases, EW better than NaClO. Non inoculated fruits did not show any negative effect after treatment with EW or with NaClO. Also, IC50 values for EW and for NaClO obtained in in vitro tests for mycelia development and spore germination of the different pathogens, correlate well with the in vivo tests. All results suggest that EW can be used as an alternative method to NaClO to control postharvest fungi of Prunus persica var. nectarine fruits , considering that the exposure times and the concentration of EW may be different, depending on the pathogen to be controlled

Selection of bioantagonistic bacteria to be used in biological control of Rhizoctonia solani in tomato

Bacteria from the rhizoplane and surrounding soil of healthy and Rhizoctonia solani diseased tomato plants, cropped in greenhouse of the V Region of Chile, were collected. The best bacterial strains, based on their ability to control development of three R. solani isolates (identified as belonging to the anastomosis groups AG-2-1, AG-4), were identified as B. subtilis (one isolate) and B. lentimorbus (two different isolates). All bacterial isolates resulted effective for the in vitro control of growth of all R. solani isolates, where the control mechanisms used by the bacteria do not involve the secretion of fungal cell wall hydrolytic enzymes. R. solani AG-2-1 was more sensitive than R. solani AG-4. On the other hand, all bacteria grew well in conditions similar to those that can be found at the field level (considering pH, salinity, Fe3+ and temperature) and showed a good capacity of tomato root colonization. These results suggest that the B. subtilis and B. lentimorbus isolates studied have an excellent potential to be used as biocontrol agents of R. solani in tomato greenhouses at the field level

New strains obtained after UV treatment and protoplast fusion of native Trichoderma harzianum : their biocontrol activity on Pyrenochaeta lycopersici

The obtainment of 30 new strains from native Trichoderma harzianum after UV light irradiation (UV-A and UV-C), and of 82 strains resulted from protoplast fusion were accomplished. The new strains, initially selected for their growing rate under low temperature and high pH conditions, as well as for their innocuousness on tomato plants, were tested for in vitro inhibition of Pyrenochaeta lycopersici in dual cultures and due to secretion of volatile and diffusible metabolites. All the UV-A and UV-C selected candidate mutants were innocuous to tomato plants, but none of them showed improvement in their biocontrol activity on P. lycopersici. Th12A20.1 increased 1.3 and 1.9 fold the total fresh weight of Fortaleza tomato plants when compared to its parental strains Th12 and Th11, respectively. The selected candidate mutants obtained through protoplast fusion were also innocuous to tomato plants, but only ThF1-2 and ThF4-4 inhibited 1.3 fold (in dual cultures) and 5 fold (due to secretion of volatile metabolites) the growth of P. lycopersici, respectively, in relation to the mean inhibitory effect of both parents. Therefore, these candidate mutants could be included in experiments under field conditions

Control Biológico de Rhizoctonia solani en Tomate en Suelos Previamente Sometidos a Solarización y Bromuro de Metilo

Se investigó el grado de control de Rhizoctonia solani mediante el uso de los bioantagonistas Paenibacillus lentimorbus, Trichoderma harzianum y T. polysporum, aplicados solos o combinados con solarización o bromuro de metilo, en un suelo naturalmente infectado. La investigación se realizó bajo invernadero, empleándose suelo previamente solarizado, bromurado en invernadero frío, tratamientos que fueron realizados en la V Región de Chile. La temperatura máxima promedio alcanzada por el suelo en esta práctica, fue de 37,6 °C. Se usó una dosis de 75,5 g m-2 de bromuro de metilo. P. lentimorbus fue aplicado al estado de plántula al momento del trasplante, en una suspensión de metilcelulosa al 2% a concentración de 5x109 ufc ml-1, mientras que T. harzianum cepa 650 (360.000 ufc g-1 de pellets) y T. polysporum cepa 34 (566.000 ufc g-1 de pellets) se aplicaron al mismo estado fenológico, formulados como pellets de alginato de sodio, en una dosis de 1,3 g de pellets por litro de suelo. Los mejores resultados de control se obtuvieron con P. lentimorbus cepa 629, además éste estimuló el crecimiento de las raíces y de la planta en general. Le siguió T. harzianum cepa 650, independientemente si el suelo tuvo tratamiento de solarización o si fue fumigado con bromuro de metilo. El comportamiento de los biocontroladores fue similar al aplicarlos después de los tratamientos de solarización y fumigación con bromuro de metilo, aunque una mayor respuesta se pudo apreciar en aquel que fue solarizado. Los resultados indicarían que la aplicación de estas especies de Trichoderma y de P. lentimorbus podría ser recomendada dentro de un programa de control integrado de R. solani ya sea aplicados por si solos o en combinación con solarización y en reemplazo al bromuro de metilo. En las condiciones de esta investigación, la solarización fue insuficiente para controlar satisfactoriamente R. Solani

Control biológico e integrado de enfermedades y nematodos en frutales y hortalizas

El control biológico de fitopatógenos y nematodos fitoparásitos, así como las prácticas de manejo integrado de los mismos, son medidas que cada día adquieren mayor importancia en Chile, ya sea por la necesidad de efectuar una producción más eco-compatible y sustentable, como por las exigencias del mercado interno y externo en los productos hortofrutícolas. En este contexto, se planteó el curso "Control biológico e integrado de enfermedades y nematodos en Frutales, y Hortalizas", organizado por el Laboratorio de Microbiología del Departamento de Sanidad Vegetal, de la Facultad de Ciencias Agronómicas de la Universidad de Chile, los dias 22 y 23 de julio de 2004. En él se trataron prácticas de control biológico de enfermedades y nematodos fitoparásitos en especies frutales, vides y en cultivos como el tomate y la frutilla; además de medidas de manejo integrado utilizando biopesticidas orgánicos, fungicidas y bactericidas inorgánicos blandos que se pueden aplicar en producción hortofrutícola orgánica. También se trataron métodos físicos de control de enfermedades y nematodos, como el uso de la solarización, luz ultravioleta, oxígeno ionizado y temperatura. Esta publicación contiene las materias de todas las clases del curso antes señalado y se espera sea de utilidad para profesionales, estudiantes, técnicos y productores del sector agrícola

Susceptibility of different grapevine (Vitis vinifera L.) cultivars to Diplodia seriata and Diplodia mutila

Canes obtained from one-year-old stems of the grapevine cultivars Cabernet Franc, Malbec, Merlot, Sauvignon Blanc and Syrah (all non-grafted) were used as models to test their susceptibility to Diplodia seriata and Diplodia mutila. The results showed that the mean length of lesions caused by D. mutila was 3.2 times larger than that produced by D. seriata. In addition, the Cabernet Franc and Syrah cultivars were the most susceptible to D. mutila, while Merlot and Malbec were the least susceptible. No significant differences were observed between cultivars inoculated with D. seriata. The results are discussed in terms of the susceptibility of the different grapevine cultivars to both pathogens.La susceptibilidad de los cultivares de vid vinífera Cabernet Franc, Malbec, Merlot, Sauvignon Blanc and Syrah (todos patrón Franco) a Diplodia seriata y Diplodia mutila se analizó usando estacas como modelo. Las estacas se obtuvieron de sarmientos de un año de edad. Los resultados mostraron que la longitud promedio de las lesiones producidas por D. mutila era 3,2 veces mayor que la producida por D. seriata. Al comparar las lesiones producidas por D. mutila en los diferentes cultivares, se encontró que Cabernet Franc y Syrah fueron los más susceptibles, mientras que Merlot y Malbec fueron los menos susceptibles. Por otra parte, no se observaron diferencias significativas en el tamaño de las lesiones producidas por D. seriata en los diferentes cultivares. Los resultados se discuten con relación a la susceptibilidad de diferentes cultivares de vid vinífera al daño producido por ambos patógenos