EFECTO DE LA APLICACIÓN DE ESTIÉRCOL SIN COMPOSTAR Y FUNGICIDAS PARA EL CONTROL DEL HONGO (Pyrenochaeta terrestris) EN CEBOLLA

El objetivo del presente trabajo fue evaluar el efecto de la aplicación de fungicidas químicos y biológicos en combinación con estiércol de bovino sin compostar sobre el control del hongo Pyrenochaeta terrestris causante de la pudrición rosada en la raíz del cultivo de la cebolla. El experimento se desarrolló en Magdalena de Kino, Sonora durante el año 2012. El diseño utilizado fue un factorial de 2x7, donde el primer factor fueron dos dosis de estiércol y el siete fungicidas. Los resultados obtenidos indicaron diferencias estadísticas en el porcentaje de incidencia y severidad del ataque del hongo, así como en altura de planta, peso de bulbo y rendimiento entre niveles de estiércol, fungicidas y en la combinación de ambos. La incidencia y la severidad del ataque del hongo se incrementaron 14% y 3% respectivamente con la aplicación de estiércol en relación al testigo. El tratamiento con Trichoderma harzianum presentó el menor grado de severidad, mayor altura de planta, peso de bulbo y rendimiento con 18%, 79 cm, 233 g y 84.3 t ha-1 respectivamente. En la combinación de estiércol-fungicida, los tratamientos que obtuvieron los mayores rendimientos fueron los aplicados con Trichoderma harzianum con y sin estiércol con 84.7 y 82.0 t ha-1.

Production and resistance of three scallion cultivars to pink root

The production of scallion has been widely exploited on small farms, since it requires little care and is largely commercialized close to the production sites. Pink root, caused by Phoma terrestris (syn. Pyrenochaeta terrestris),is among the main diseases affecting this crop. However, little information on aspects related to yield and few cultivars resistant to the disease are available. In this study we evaluated these variables on Konatsu, Natsu and Nebuka cultivars. The experiment was carried out in Lontras, Santa Catarina state, Brazil, in a complete randomized blocks design with four replications. After 80 days of transplantation the following parameters were evaluated: plant mass, total and marketable number of leaves, total and marketable mass of leaves, lenght and weight of roots. The total number of bunches was assessed as an evaluation aiming the market. The disease severity, in percentage on the root system, was assessed for the pink root. The average values of the variables were subjected to analysis of variance by F test and mean comparison test by Tukey, 5%. The Konatsu cultivar presented higher average mass per plant (159 g plant-1) compared to Nebuka and Natsu cultivars. The average mass of marketable leaves for 'Konatsu' was 56.17% higher than for 'Nebuka'. The number of bunches produced by 'Konatsu' was 48% higher than for 'Nebuka'. The cultivar Konatsu was, therefore, more productive and resistant to the pink root disease.

The incidence of Pyrenochaeta terrestris in root of different plant species in Serbia

Root samples of cereals (oats, wheat, barley, maize and sorghum), vegetables (garlic, onion, pepper, cucumber, pumpkin, carrot and tomato), industrial plant (soya bean) and weeds (Johnson grass, barnyard grass and green bristle-grass) collected in different agroecological conditions in Serbia were analysed for the presence of Pyrenochaeta terrestris. The fungus was found in 42 out of 51 samples (82.4%), while the incidence varied from 2.5 to 72.5%. The highest incidence was detected in cereals (average 30.3%), and then in weeds of the Poaceae family (average 14.2%). Considering single species, maize (up to 72.5% in root) and Johnson grass (up to 37.5%) were mostly attacked by this fungus. The lowest incidence of the fungus was determined in vegetable crops (average 6.7%). Red to reddish discoloration of root was correlated with the incidence of the fungus. Obtained data indicate that P. terrestris is widespread in Serbia and conditions for its development are favourable.