PRINCIPALES HONGOS FITOPATOGENOS ASOCIADOS A BULBOS ALMACENADOS DE AJO ELEFANTE (Allium ampeloprasum var. holmense) DE LA ZONA DE QUILLOTA Y NOGALES (CHILE)

Se presentan los primeros antecedentes fitopatológicos referentes a una prospección de hongos presentes en bulbos almacenados y plantas deAllium ampeloprasum var. holmense (ajo elefante) provenientes de las zonas de Quillota y Nogales (V Región). A partir de bulbos con diferentes lesiones,se realizaron aislamientos fúngicos correspondientes a lossiguientes taxa: Penicillium hirsutum, P.aurantiogriseum, P.echinulatum, P.funiculosum, P.rugulosum, Fusarium oxysporum y Embellisia allii. Estos se inocularon para efectuar pruebas de patogenicidad; tantoen bulbos como en plantas en maceta (salvo Penicillium spp.).Los resultados obtenidos en bulbos almacenados indicaron que el principal problema en las muestras analizadas fue Penicillium hirsutum, asociado a lesiones inicialmente hendidas, secas, rodeadas de unhalo blanquecino, presentando al cabo de 7 días una pudrición blanda acuosa que involucraba la totalidad del bulbo, apareciendo posteriormente el moho azul en las lesiones. Los problemas de importancia secundaria para esta especie vegetal en la zona estudiadafueron Fusarium oxysporum y Embellisia allii. El principal problema en las plantas en maceta fue E. allii, el cual bajo condiciones de humedadprevia y en períodos cercanos a la cosecha, afectó al bulbo cubriéndolo de un micelio negro.

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

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

Evaluation of DMI fungicides against species of Diplodia and Neofusicoccum associated with Botryosphaeria canker of grapevine

The Botryosphaeriaceae species have been widely studied and are considered a serious problem to the production of grapes worldwide. To aid in the development of control strategies for these fungi, in vitro experiments were conducted to evaluate the effectiveness of demethylation inhibiting (DMI) fungicides against Diplodia seriata, D. mutila, Neofusicoccum australe and N. parvum isolated from grapevine (Vitis vinifera). Fungicidal effectiveness was evaluated over a range of increasing concentrations using measurements of both the inhibition of conidial germination and the effects on mycelial growth. The effective concentrations (EC) necessary to inhibit conidial germination and mycelial growth by 50% (EC50) and 90% (EC90) were estimated by linear regression analysis between x = log10 of the fungicidal concentration and y = the Probit value of the inhibition percentage. The results demonstrate that tebuconazole, myclobutanil, prochloraz and prochloraz plus epoxiconazole exhibit considerable in vitro activity against D. mutila, D. seriata, N. australe and N. parvum. These DMI compounds were able to arrest conidial germination and inhibit mycelial growth. The EC50 values obtained for conidial germination were generally higher than the EC50 values obtained for mycelial growth, suggesting that mycelia are more sensitive to the DMI compounds than are conidia. However, the effectiveness of these DMI compounds in the vineyard must be studied before any final conclusions can be reached.Las especies de Botryosphaeriaceae han sido ampliamente estudiadas y se considera un importante problema para el cultivo de la vid (Vitis vinifera) a nivel mundial. Este trabajo tuvo por objetivo estudiar la efectividad de inhibidores de la biosíntesis de esteroles, fungicidas DMI, en inhibir la germinación conidial y el crecimiento micelial de tres aislados de las especies Diplodia seriata y D. mutila, dos aislados de Neofusicoccum australe y uno de N. parvum, obtenidos de vides. Las concentraciones efectivas necesarias para inhibir en un 50% (EC50) y 90% (EC90), la germinación conidial y el crecimiento micelial, se estimaron por análisis de regresión lineal entre x= log10 de la concentración de fungicida e y= el valor Probit del porcentaje de inhibición. Los resultados de este estudio mostraron que tebuconazol, miclobutanil, procloraz y procloraz más epoxiconazol tienen una considerable actividad in vitro contra D. mutila, D. seriata, N. australe y N. parvum. Estos compuestos DMI fueron capaces de detener la germinación conidial e inhibir el crecimiento micelial. Los valores de EC50 obtenidos para la germinación conidial fueron más altos que los valores de EC50 obtenidos para el crecimiento micelial, lo que sugiere que el micelio fue más sensible a los compuestos DMI que las conidias. Queda por estudiar la eficacia de estos compuestos DMI en los viñedos antes de llegar a una conclusión final

Prevalence and pathogenicity of fungi associated with grapevine trunk diseases in Chilean vineyards

G. A., Diaz, J., Auger, X., Besoain, E., Bordeu, and B. A. Latorre, 2013. Prevalence and pathogenicity of fungi associated with grapevine trunk diseases in Chilean vineyards. Cien. Inv. Agr. 40(2): 327-339. Trunk diseases in grapevine (Vitis vinifera) have been identified as a major problem in the wine and table grape industries around the world, reducing the productivity, quality and longevity of vineyards. The present study examined 694 wood samples from the cordons and trunks of vines with trunk disease symptoms in 67 Chilean vineyards located between Copiapó (27°18' S) and Los Angeles (37°42' S). A total of 1,363 fungal isolates were obtained from diseased cordons and trunks with dark brown streaking, yellowish soft-spongy cankers and brown hard V-shaped cankers. Using molecular identification, a total of 12 fungal genera were identified in Chile at varying frequencies: Phaeomoniella chlamydospora (85%); Botryosphaeriaceae (56%) including Diplodia mutila, D. seriata, Neofusicoccum parvum and Spencermartinsia viticola; Inocutis sp. (47%); Diatrypaceae (Cryptovalsa ampelina and Eutypella leprosa) (4.8%); Seimatosporium botan (1.7%); Phomopsis viticola (0.4%); Cylindrocarpon sp. (0.4%); and Phaeoacremonium aleophilum (0.2%). All species were pathogenic, inducing dark brown streaking on various aged grapevine wood tissue. In conclusion, several fungal species are associated with grapevine trunk diseases in the Chilean vineyards being Pa. chlamydospora, D. seriata and Inocutis sp. the most frequent isolated species. These are pathogens that can be found alone or they can coexist in the same plant. This is the first report of Pho. viticola associated with trunk diseases in Chile.G.A., Díaz, J., Auger, X., Besoain, E., Bordeu y B.A. Latorre. 2013. Prevalencia y patogenicidad de hongos asociados con enfermedades de la madera en viñedos Chilenos. Cien. Inv. Agr. 40(2): 327-339. Las enfermedades de la madera de la vid (Vitis vinifera) se han identificado como un importante problema sanitario de la industria vitícola en el mundo, reduciendo la productividad, calidad y longevidad de los viñedos. En el presente estudio se examinó 694 muestras de brazos y troncos de vides con cancrosis en la madera recolectada en 67 viñedos entre Copiapó (27° 18' S) y Los Ángeles (37° 42' S), Chile. Se obtuvieron 1.363 aislados fúngicos desde brazos y troncos enfermos, caracterizados por presentar estrías necróticas vasculares, cancros blandos, esponjosos, blanco-cremosos y cancros firmes en consistencia, pardos, a menudo en forma de V e cortes transversales. Por análisis molecular de la región ITS del ADNr, se identificaron 12 géneros de hongos fitopatógenos los correspondieron a: Phaeomoniella chlamydospora (85%), especies de Botryosphaeriaceae (56%) (Diplodia mutila, D. seriata, Neofusicoccum parvum y Spencermartinsia viticola), Inocutis sp. (47%), Diatrypaceae spp. (Cryptovalsa ampelina y Eutypella leprosa) (4,8%), Seimatosporium botan (1,7%), Phomopsis viticola (0,4%), Cylindrocarpon sp. (0,4%) y Phaeoacremonium aleophilum (0,2%). Estas especies fueron patogénicas, induciendo estrías necróticas vasculares, pardo oscuras, a negras en tejidos semi-lignificados y lignificados de vid. En conclusión, varias especies de hongos fitopatógenos están asociados a cancrosis de la madera en viñedos siendo Pa. chlamydospora, D. seriata e Inocutis sp. las especies mas frecuentemente encontradas. Estos hongos fitopatógenos pueden encontrarse solos o se pueden encontrar coexistiendo en la misma planta. Este es el primer reporte de Pho. viticola asociado con enfermedades de la madera en Chile

Botryosphaeriaceae species affecting table grape vineyards in Chile and cultivar susceptibility

Several Botryosphaeriaceae species have been identified as the causes of cankers and dieback of Vitis vinifera in several grape-growing regions around the world. This research was conducted to further study the species of Botryosphaeriaceae associated with table grapes in Chile, to estimate the prevalence and severity of the disease as a function of vineyard age, to study the susceptibility of table grape cultivars to infection by Botryosphaeriaceae species, and to evaluate the effect of tissue age on the infection caused by Botryosphaeriaceae species. Symptoms were characterized by the presence of the partial or total death of the grapevine cordons and distorted leaves. Brown V-shaped or U-shaped cankers and black spots were observed in cross-sections, while brown vascular streaks were observed in longitudinal sections of the cordons and trunks. Pathogenic isolates of Diplodia seriata, D. mutila and Spencermartinsia viticola were consistently obtained from wood cankers and/or vascular streaking; D. seriata was the most common (83.3%) Botryosphaeriaceae species. In 11- to 20-year-old vineyards, the disease incidence varied between 22.0 and 69.0%, and the severity varied between 6.0 and 21.3%. The table grape cultivars 'Thompson Seedless', 'Redglobe' and 'Flame Seedless' were equally susceptible to infection by D. mutila, D. seriata and S. vitícola. The age of the inoculated tissue had no significant effect on the development of the vascular necrosis. This is the first report of D. mutila and S. viticola infections of grapevines in Chile.Diversas especies de Botryosphaeriaceae se han identificado como causantes de cancros y muerte regresiva en Vitis vinifera en diferentes regiones donde se cultivan vides en el mundo. Esta investigación tuvo el propósito de determinar nuevas especies de Botryosphaeriaceae asociadas a uva de mesa en Chile, determinar la incidencia y severidad de las especies de Botryosphaeriaceae asociadas al decaimiento de vides, evaluar la susceptibilidad de cultivares y determinar el efecto de la edad del tejido en el desarrollo de cancrosis y necrosis vascular. Los síntomas observados se caracterizaron por la presencia de brotes débiles y decaimiento generalizado de las vides. Internamente, se observaron cancros de color café en forma de o "U" ó de "V" y estrías necróticas vasculares. Aislados patogénicos de Diplodia seriata, D. mutila y Spencermartinsia viticola se obtuvieron consistentemente desde cancros en la madera y/o estrías vasculares, siendo D. seriata la especie más frecuentemente aislada (83,3%). En parronales de uva de mesa de 11 a 20 años de edad, la incidencia de la enfermedad varió entre un 22,0 a un 69,0%, y la severidad entre 6,0 y 21,8%. Los cultivares de uva de mesa 'Thompson Seedless', 'Redglobe' y 'Flame Seedless' fueron igualmente susceptibles a infección por D. mutila, D. seriata y S. viticola. La edad de los tejidos inoculados no tuvo un efecto significativo en el desarrollo de la necrosis. Estos resultados constituyen la primera mención de D. mutila y S. viticola en vides en Chile

In vitro and glasshouse biocontrol of Rhizoctonia solani with improved strains of Trichoderma spp.

J.R. Montealegre, F. Ochoa, X. Besoain, R. Herrera, and L.M. Pérez. 2014. In vitro and glasshouse biocontrol of Rhizoctonia solani with improved strains of Trichoderma spp. Cien. Inv. Agr. 41(2):197-206. The potential of Trichoderma spp. fusants for the biocontrol of Rhizoctonia solani was compared with the ability of their corresponding parental strains. Their effect was tested in vitro using two R. solani strains, 509 (AG 2-1) and 618 (AG 4). The highest inhibitions in growth in dual cultures were obtained with the ThF2-1 (89.79%), ThF3-3 (90.55%), ThF4-15 (91.75%) and ThF5-8 (77.67%) fusants on R. solani 509; only ThF2-1 was able to inhibit the growth of R. solani 618 (60.19%). The inhibitory effect on growth was mainly due to diffusible metabolites. Percent mortality and canker level in tomato plants were evaluated in glasshouse experiments where all of the evaluated fusants suppressed plant mortality, but only ThF2-1 and ThF5-8 significantly decreased the canker level.J.R. Montealegre, F. Ochoa, X. Besoain, R. Herrera y L.M. Pérez. 2014. Biocontrol de Rhizoctonia solani in vivo y en invernadero, con cepas mejoradas de Trichoderma spp. Cien. Inv. Agr. 41(2):197-206. Se comparó la capacidad de cepas de Trichoderma spp., obtenidas previamente por fusión de protoplastos, con la de sus correspondientes cepas parentales, para biocontrolar a Rhizoctonia solani. El efecto biocontrolador se analizó sobre dos cepas de R. solani: 509 (GA 2-1) y 618 (GA 4). Las cepas producto de fusión de protoplastos de Trichoderma spp. fueron más efectivas que al menos una de las correspondientes cepas parentales. La inhibición más alta en experimentos de cultivos duales, se observó con las cepas ThF2-1 (89,79%), ThF3-3 (90,55%), ThF4-15 (91,75%) y ThF5-8 (77,67%) sobre R. solani 509; mientras que el efecto biocontrolador sobre R. solani 618, sólo logró un 60,19% de inhibición con la cepa ThF2-1. El efecto inhibidor del desarrollo se debió principalmente a la secreción de metabolitos difusibles. El porcentaje de mortalidad y nivel de cancro en plantas de tomate se evaluó en experimentos de invernadero, en los que todas las cepas producto de la fusión de protoplastos de Trichoderma spp. suprimieron la mortalidad de plantas de tomate, y solamente ThF2-1 y ThF5-8 disminuyeron significativamente el nivel de cancro

Sensitivity of wild-type and mutant Trichoderma harzianum strains tofungicides

The germination of conidia in wild-type (Th11, Th12 and Th650) and mutant (Th11A80.1, Th12A10.1 and Th650-NG7) strains of Trichoderma harzianum that were exposed to different commercial fungicides was studied. All wild-type and mutant Trichoderma strains were germinated in the presence of 1,700 mg L-1 of pencycuron. The wild-type strains Th12 and Th650 and the corresponding mutant strains Th12A10.1 and Th650-NG7 were sensitive to all concentrations of iprodione and metalaxil + mancozeb. The EC50 (Median Effective Concentration) values for the different fungicides were between 10-1 and 10-4 less than the concentrations recommended for field applications; one exception was Phyto-fos on Th650-NG7, where this ratio was 0.72. These results establish whether some of these fungicides can be used in combination with the biocontrol agents evaluated.Se estudió la germinación de conidias de cepas silvestres de Trichoderma harzianum (Th11, Th12 y Th650) y de sus correspondientes cepas mutantes (Th11A80.1, Th12A10.1 y Th650-NG7) sometidas a dosis crecientes de distintos fungicidas comerciales. Tanto las cepas silvestres de Trichoderma como las mutantes germinaron a 1.700 mgL-1 de pencycuron, mientras que las cepas silvestres Th12 y Th650 y sus correspondientes mutantes Th12A10.1 y Th650-NG7 fueron sensibles a todas las concentraciones de iprodione y metalaxil+mancozeb. La mayoría de los valores de CE50 (Concentración Efectiva Media) para los diferentes fungicidas variaron desde 10-1 a 10-4 veces la concentración recomendada para uso a nivel de campo, excepto para Phytofos sobre la cepa mutante Th650-NG7, donde este valor fue de 0,72. Los resultados permiten establecer que algunos de estos fungicidas podrían utilizarse en combinación con agentes biocontroladores