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Previous studies of European populations of the blast fungus (Magnaporthe oryzae) have shown the existence of five clonal lineages. Three of them were common to different countries, whereas one was specific to Hungary and another was specific to Spain. But these studies were carried out on a limited number of individuals and pointed out a need for more extensive studies in each European rice-growing area. In addition, temporal evolution of M. oryzae populations is also poorly documented. In this study, we focused on Guadalquivir delta region in southern Spain. A total of 186 M. oryzae isolates were collected from various farmer and experimental fields, on diverse cultivars, over the period 1999-2003, and characterized for their genotypic and pathotypic diversity. Five lineages were identified, one of which was detected for the first time in Europe (E6). The E6 lineage, which was collected over the period 2000-2003, became dominant in 2000. Pathotyping confirmed previous results of a narrow diversity for virulence spectrum in European lineages. Five dominant pathotypes were identified, each one corresponding to a single pathotype. Drastic changes in lineage relative frequencies were observed from one year to another. The origin of such changes is discussed. (Resume d'auteur)

Field and laboratory studies were conducted from 1993 to 1997 to determine the feasibility of controlling nodding broomrape in sunflower by treating crop seeds with pronamide. Soaking sunflower seeds for 5 min in 50% pronamide solution or coating at the equivalent of 2 kg/ha with pronamide did not impair seed germination or seedling growth, and controlled nodding broomrape 49 to 68% and 51 to 77%, respectively, up to 105 d after planting. Studies of the effect of treated sunflower seeds on germination and seedling growth, at several time intervals after the herbicide application (0, 30, 60, and 90 d after treatment [DAT]), were conducted. Soaking with 50% solution or coating at 2 kg/ha reduced seedling growth by 20 and 24% 60 DAT, respectively, compared with the control. Nomenclature: Pronamide; nodding broomrape, Orobanche cumana Wallr. #3 ORACU; sunflower, Helianthus annuus L. Additional index words: Herbicide seed treatment, parasitic weed. Abbreviations: DAP, days after planting; DAT, days after treat...

Studies were conducted from 1993 through 1995 to determine broomrape control from imazethapyr applied to pea seeds. Soaking seeds for 1 to 10 min in 0.0001% to 1% imazethapyr (Pursuit-10) solutions or coating seeds with imazethapyr at 0.025 to 0.30 mg/g (herbicide/seed, equivalent to 5 to 60 g/ha for a seeding rate of 200 kg/ha) did not affect seed germination or crop emergence and growth. Broomrape control with imazethapyr applied by coating seed at 0.1 to 0.2 mg/g (herbicide/seed, 20 to 40 g/ha) or by soaking seeds for 5 min in 0.1% to to 1% imazethapyr solution was from 75 to 80% and 50 to 70%, respectively. Pea biomass and seed yield increased, compared to broomrape-infested nontreated control, when pea seeds were treated with imazethapyr and imazapyr at 5 g/ha was applied late postemergence, as a result of the excellent broomrape control. Nomenclature: Imazethapyr, 2[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid; broomrape, Orobanche crenata Forsk. # 3 ORACR; pea, Pisum sativum L.

Summary: Resume: Zusammenfassung Field experiments were conducted from 1989 to 1992 to determine the effects of pre-emergence herbicides in sunflower (Helianthus armuus L.) on: (1) the control of Orobanche cemua Loefl. (broomrape) and (2) crop damage and crop yield. Herbicides tested belong to the imidazolinone, sulfonylurea and substituted amide families. Imazethapy r (20–40 g ha−1), imazapy r (12.5–25 gha−1) and chlorsulfuron (4–6 gha−1) controlled broomrape efficiently without crop injury. With good O. cernua control and good crop tolerance, sunflower seed yield from these treatments were generally similar to the non-infested checks and higher than the infestedchecks. Imazaquin (20–40 gha−1), triasulfuron(4gha−1), pdmisulfuron(3g ha−1), acetochlor (4–4 kg ha−1) and metazachlor (2 kg ha−1) were less effective. Imazamethabenz (200–600 g ha−1) and metolachlor (3–3 kg ha−1) were ineffective. Wetconditions aftercropsowing considerably decreased O. cemua control with pre-emergence herbicides probably caused by enhanced degradation. Des herbicides de prelevee pour la lutte contre Vorobanche (Orobanche cemua Loefl.) dans le toumesol (Helianthus annuus L.) Des experimentations au champ ont ete conduites de 1989 a 1992 pour determiner les effets d'herbicides de pre1evee du toumesol sun (a) la destruction de l'orobanche (Orobanche cernua Loefl.) et (b) la phytotoxcite sur la culture. Les herbicides testes appartenaient aux imidazolinones, aux sulfonylurdes et aux amides substituees. L'imazethapyr (20 a 40 gha−1), l'imazapyr (12,5 a25gha−1)et le chlorsulfuron (4 a 6 gha−1) detruisaient efficacement l'orobanche sans occasionner de phytotoxidt6 sur la culture. Dans ces conditions, les rendements etaient generalement semblables a ceux des temoins non infestes et superieurs a ceux des temoins infestes. L'imazaquin (20 a 40 g ha−1), le triasulfuron (4 gha−1), le primisulfuron (3 g ha−1), lacetolachlor (4,4 kg ha−1) et le metazachlor (2 kg ha−1) etaient moins efficaces. L'imazamethabenz (200 a 600 g ha−1) et le metolachlor (3,3 kg ha−1) etaient inefficaces. Des conditions humides aprfes le semis diminuaient considerablement la destruction de O. cemua par les herbicides de prelevee, probablement a cause d'une degradation plus elevee. Vorauflaufherbigide zur Bekdmpfung der Sommerwurz Orobanche cemua Loefl. in Sonnenblume (Helianthus annuus L.) Zwischen 1989 und 1992 wurden in Sonnenblume Feldversuche zur Wirkung von Vorauflaufherbiziden aus den Gruppen der Imidazolinone, Sulfonylharnstoffe und substitutierten Amide auf die Sommerwurz Orobanche cernua und auf Kulturpflanzenschaden sowie den Ertrag durchgefuhrt. Mit Imazethapyr (20 bis 40 g ha−1), Imazapyr (12,5 bis 25 g ha−1) und Chlorsulfuron (4 bis 6 g ha−1) lieβ sich die Sommerwurz wirksam bekampfen, ohne daβ Schaden an der Sonnenblume auftraten, und die Ertrage waren allgemein ahnlich oder hoher als bei der nichtparasitierten Kontrolle. Imazaquin (20 bis 40 ha−1), Triasulfuron (4 g ha−1).Primisulfuron (3 g ha −1). Acetochlor (4,4 kg ha −1 und Metazachlor (2 kg ha −1) waren weniger wirksam. Imazamethabenz (200 bis 600 g ha−1) und Metolachlor (3,3 kg ha−1) hatten keine Wirkung. Bei Niederschlagen nach der Saat der Sonnenblume war die Bekampfung der Sommerwurz mit Vorauflaufherbiziden vermutlich wegen verstarkten Abbaus erheblich schwacher.

The rice (Oryza sativa L.) cultivars Puntal and Thaibonnet were used in a field trial designed to investigate how temperature and relative humidity affect the airborne concentration of Pyricularia oryzae spores and the development of rice blast. A relative humidity of 95% and an average temperature of 26-27 deg C were optimum for infection and substantially favoured spore release. The first symptoms of infection were detected on the leaves when the crop was at the mid-tillering stage, the number of lesions increasing as the plant developed. After the onset of heading the number of leaf lesions decreased while the number of node and panicle base lesions increased. A temperature increase of 1 deg C in early August (mid-tillering stage) led to an increase in the mean intensity of disease. The presence of spores in the air from July 15th predicted the appearance of leaf lesions a few days later. The peak spore concentration in August could be used to forecast panicle blast. Assessing the airborne concentration of P. oryzae could help in understanding the population dynamics of this pathogen., Los cultivares de arroz Puntal y Thaibonnet fueron sembrados en campo para analizar el efecto de la temperatura y la humedad relativa media sobre el contenido de esporas de Pyricularia oryzae en el aire y el progreso de la enfermedad. Valores de humedad relativa del 95% y temperatura media entre 26-27 grados C propician condiciones óptimas para la infección del patógeno y favorecen sustancialmente la expulsión de esporas. Los primeros síntomas aparecieron sobre hojas, cuando el cultivo se encontraba en estado de ahijado medio. La cantidad de lesiones infecciosas en hoja incrementó conforme la planta aumentaba su desarrollo. Después del inicio de espigado estos valores decrecieron, mientras que los valores de infección en nudo y base de la panícula se incrementaron paulatinamente. Un incremento de temperatura de 1 grado C a principios de agosto (estado de ahijado medio) causó un incremento de la intensidad media de la enfermedad. La presencia de esporas en el aire desde el 15 de julio ayuda a predecir la aparición de manchas en hojas varios días más tarde. El pico de esporas registrado en agosto puede ser usado para predecir la infección en panícula. La evaluación del contenido de las esporas de P. oryzae en el aire ayuda a comprender la dinámica de la población del patógeno.

The rice (Oryza sativa L.) cultivars Puntal and Thaibonnet were used in a field trial designed to investigate how temperature and relative humidity affect the airborne concentration of Pyricularia oryzae spores and the development of rice blast. A relative humidity of 95% and an average temperature of 26-27 deg C were optimum for infection and substantially favoured spore release. The first symptoms of infection were detected on the leaves when the crop was at the mid-tillering stage, the number of lesions increasing as the plant developed. After the onset of heading the number of leaf lesions decreased while the number of node and panicle base lesions increased. A temperature increase of 1 deg C in early August (mid-tillering stage) led to an increase in the mean intensity of disease. The presence of spores in the air from July 15th predicted the appearance of leaf lesions a few days later. The peak spore concentration in August could be used to forecast panicle blast. Assessing the airborne concentration of P. oryzae could help in understanding the population dynamics of this pathogen. Los cultivares de arroz Puntal y Thaibonnet fueron sembrados en campo para analizar el efecto de la temperatura y la humedad relativa media sobre el contenido de esporas de Pyricularia oryzae en el aire y el progreso de la enfermedad. Valores de humedad relativa del 95% y temperatura media entre 26-27 grados C propician condiciones óptimas para la infección del patógeno y favorecen sustancialmente la expulsión de esporas. Los primeros síntomas aparecieron sobre hojas, cuando el cultivo se encontraba en estado de ahijado medio. La cantidad de lesiones infecciosas en hoja incrementó conforme la planta aumentaba su desarrollo. Después del inicio de espigado estos valores decrecieron, mientras que los valores de infección en nudo y base de la panícula se incrementaron paulatinamente. Un incremento de temperatura de 1 grado C a principios de agosto (estado de ahijado medio) causó un incremento de la intensidad media de la enfermedad. La presencia de esporas en el aire desde el 15 de julio ayuda a predecir la aparición de manchas en hojas varios días más tarde. El pico de esporas registrado en agosto puede ser usado para predecir la infección en panícula. La evaluación del contenido de las esporas de P. oryzae en el aire ayuda a comprender la dinámica de la población del patógeno.

The susceptibility of 14 commercial rice cultivars to Pyricularia oryzae was tested under field conditions agronomically appropriate for natural infection to occur. The first symptoms of infection were detected on the leafs when the crops were at the medium tillering stage. Generally speaking, the incidence of infection for each particular cultivar was similar in the 2002 and 2003 seasons and at the two trial locations (the Sartenejales and Casudis estates in the Province of Seville). The pathogen infected 80-100% of "Maratelli", "Baixet", "Thainato" and "Galatxo" plants. Differences were seen among the cultivars with respect to the parts of the plant affected. "Baixet" and "Maratelli" were the most susceptible cultivars, followed by "Thainato". "Ullal" was the most tolerant, followed by "Marisma", "Puebla", "Maso", "L-202", "Susan", "Doongara", "Fonsa" and "Jacinto"; these last six cultivars showed medium disease severity according to the scale used in this work. Further studies on the interactions between different strains of P. oryzae and rice cultivars are underway., Se sembró en campo una colección de 14 cultivares comerciales de arroz bajo condiciones agronómicas apropiadas para que se produzca la infección natural por Pyricularia oryzae, a fin de estudiar su susceptibilidad al patógeno. Los primeros síntomas de la infección se detectaron en las hojas cuando el cultivo se encontraba en estado de ahijado medio. Generalmente, la incidencia de la enfermedad fue similar para cada cultivar en dos campañas (2002-2003) y localidades (Sartenejales y Casudis, Sevilla). El patógeno infectó el 80-100% de las plantas de "Maratelli", "Baixet", "Thainato" y "Galatxo". Se observaron diferencias entre los cultivares estudiados relativas a las partes de las plantas afectadas. Considerando el porcentaje de infección ponderado, "Baixet" y "Maratelli" fueron los cultivares más susceptibles al patógeno, seguidos de "Thainato". Por otro lado, "Ullal" fue el más resistente a P. oryzae, seguido de "Marisma", "Puebla", "Maso", "L202", "Susan", "Doongara", "Fonsa" y "Jacinto". Estos últimos seis cultivares mostraron una severidad de enfermedad media. Se están llevando a cabo estudios adicionales para conocer el espectro de razas de P. oryzae y su respuesta patogénica frente a una colección de cultivares diferenciales.

The susceptibility of 14 commercial rice cultivars to Pyricularia oryzae was tested under field conditions agronomically appropriate for natural infection to occur. The first symptoms of infection were detected on the leafs when the crops were at the medium tillering stage. Generally speaking, the incidence of infection for each particular cultivar was similar in the 2002 and 2003 seasons and at the two trial locations (the Sartenejales and Casudis estates in the Province of Seville). The pathogen infected 80-100% of "Maratelli", "Baixet", "Thainato" and "Galatxo" plants. Differences were seen among the cultivars with respect to the parts of the plant affected. "Baixet" and "Maratelli" were the most susceptible cultivars, followed by "Thainato". "Ullal" was the most tolerant, followed by "Marisma", "Puebla", "Maso", "L-202", "Susan", "Doongara", "Fonsa" and "Jacinto"; these last six cultivars showed medium disease severity according to the scale used in this work. Further studies on the interactions between different strains of P. oryzae and rice cultivars are underway. Se sembró en campo una colección de 14 cultivares comerciales de arroz bajo condiciones agronómicas apropiadas para que se produzca la infección natural por Pyricularia oryzae, a fin de estudiar su susceptibilidad al patógeno. Los primeros síntomas de la infección se detectaron en las hojas cuando el cultivo se encontraba en estado de ahijado medio. Generalmente, la incidencia de la enfermedad fue similar para cada cultivar en dos campañas (2002-2003) y localidades (Sartenejales y Casudis, Sevilla). El patógeno infectó el 80-100% de las plantas de "Maratelli", "Baixet", "Thainato" y "Galatxo". Se observaron diferencias entre los cultivares estudiados relativas a las partes de las plantas afectadas. Considerando el porcentaje de infección ponderado, "Baixet" y "Maratelli" fueron los cultivares más susceptibles al patógeno, seguidos de "Thainato". Por otro lado, "Ullal" fue el más resistente a P. oryzae, seguido de "Marisma", "Puebla", "Maso", "L202", "Susan", "Doongara", "Fonsa" y "Jacinto". Estos últimos seis cultivares mostraron una severidad de enfermedad media. Se están llevando a cabo estudios adicionales para conocer el espectro de razas de P. oryzae y su respuesta patogénica frente a una colección de cultivares diferenciales.

6 pages; 3 figures; 2 tables, Field and laboratory studies were conducted from 1993 to 1997 to determine the feasibility of controlling nodding broomrape in sunflower by treating crop seeds with pronamide. Soaking sunflower seeds for 5 min in 50% pronamide solution or coating at the equivalent of 2 kg/ha with pronamide did not impair seed germination or seedling growth, and controlled nodding broomrape 49 to 68% and 51 to 77%, respectively, up to 105 d after planting. Studies of the effect of treated sunflower seeds on germination and seedling growth, at several time intervals after the herbicide application (0, 30, 60, and 90 d after treatment [DAT]), were conducted. Soaking with 50% solution or coating at 2 kg/ha reduced seedling growth by 20 and 24% 60 DAT, respectively, compared with the control., Spanish Scientific and Technological Committee (CICYT:PTR92 0057; PTR 94 0184 and AGF 95 0103).

The interaction of the parasitic plant Orobanche cernua with resistant and susceptible cultivars of Helianthus annuus L. was investigated. Using different bioassays to evaluate the early stages of the parasite life cycle (germination, attachment, penetration, and establishment), differences were observed between O. cernua-resistant and O. cernua-susceptible sunflower varieties. Germination of O. cernua seeds in the presence of resistant sunflower roots was approximately half that of germination in the presence of susceptible roots, and germinated seeds displayed enhanced browning symptoms. Parasite radicles or host-tissue around the contact point turned brown after O. cernua attachment to sunflower roots, especially in the resistant varieties. These observations suggested the possible accumulation of toxic compounds as a defence strategy in the resistant sunflower varieties. Sunflower 7-hydroxylated simple coumarins may play a defensive role against O. cernua parasitism by preventing successful germination, penetration and/or connection to the host vascular system. This hypothesis is supported by the following data: (i) coumarins inhibited the in vitro germination of O. cernua seeds induced by the strigol analogue GR(24) and caused a browning reaction in germinated seeds and (ii) resistant sunflowers accumulated higher levels of coumarins in roots and excreted greater amounts than susceptible varieties in response to O. cernua infection.

Referencia OEPM: P9802354.-- Fecha de solicitud: 11/11/1998.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC)., El objeto del presente certificado de adición es una mejora introducida en la patente nº 9402328, de título "Procedimiento de utilización selectiva del herbicida imazapir en el cultivo de girasol para el control de la maleza parásita jopo (Orobanche cernua Loefl./ O. cumana Wallr.)". Dicha mejora de Patente consiste en la aplicación combinada en post-emergencia de girasol (Helianthus annuus L.) de los herbicidas imazapir y glifosato (n-fosfonometil glicina) para el control de la mala hierba parásita jopo. Esta aplicación se realiza en unas fases de desarrollo del cultivo y a unas dosis definidas de herbicidas por hectárea.

8 pages, 2 tables, 2 figures, [14C]-Imazethapyr was applied as a seed treatment and at plant pre-emergence and post-emergence to peas (Pisum sativum L.) parasitized by Orobanche crenata Forsk. Herbicide uptake increased with time regardless of the application method. Uptake reached about 98%, 89%, 81% and 94% of the total herbicide applied for the seed coating, seed soaking, pre-emergence and post-emergence treatments respectively. Herbicide translocation within the host plants consistently differed between O. crenata-infected and non-infected plants. High levels of 14C activity were accumulated by parasitic plants from the host. In non-infected pea plants, pods were stronger sinks for imazethapyr than the other parts of the plant, regardless of the application method. The herbicide distribution in the pea plant: O. crenata complex showed the same pattern regardless of the application methods. However, accumulation of radioactivity in the parasite was lower with pre-emergence and post-emergence application than with the seed treatments. In addition, radioactivity concentration in O. crenata plants was slightly higher when [14C]-imazethapyr was applied to pea seeds by coating than by soaking.

8 pages, 2 figures, Studies were conducted from 1993 to 1995 in Southern Spain to determine the feasibility of controlling broomrape (Orobanche crenata Forsk.) in broad bean (Vicia faba L.) and lentil (Lens culinaris L.) by treating seeds with imazethapyr and imazapyr. In the broad bean, soaking for 5 min in 0·01–0·1% herbicide solutions or coating at 20–40 g ha−1 (seed sowing rate 160 kg ha−1) with imazethapyr (Pursuit-10) did not affect seed germination and crop growth, and resulted in 60–80% broomrape control. Furthermore, broad bean seeds treated with imazethapyr followed by an additional late post-emergence application of imazapyr (Arsenal-25) at 5 g ha−1 resulted in excellent broomrape control (>95%). Similarly, lentil seed treatments with imazapyr by coating seeds at rates equivalent to 5–10 g ha−1 or by soaking for 5 min in 0·25% solutions did not affect germination or crop growth, and controlled 85–95% of broomrape. As a result, with broomrape-efficient herbicide treatments, crop biomass/seed yield increased as compared to broomrape-infested, non-treated controls. Herbicide seed treatments with imazapyr in broad bean and with imazethapyr in lentil were less well tolerated and were less effective in controlling broomrape than treatments with imazethapyr and imazapyr, respectively.

Referencia OEPM: P9402149.-- Fecha de solicitud: 14/10/1994.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).

5 pages, 2 figures, 4 tables, Field studies were conducted at nine locations in southern Spain during 2 yr to develop models of nodding broomrape competition with sunflower and to establish economic thresholds. At each location, 30 to 35 small plots, each consisting of three sunflower plants, were chosen at random. The infection severity (BIS, no. of emerged broomrapes per sunflower plant) varied from 0 to 35. Plots were harvested at maturity to assess several sunflower and broomrape population variables. The percent sunflower yield reduction averaged over locations due to broomrape was estimated by the equation: % SYR= 1.7 × BIS (r² = 0.92). Crop yield loss per BIS unit increased with the expected yield and was estimated to be about 25, 50, and 75 kg ha-¹ for yields of 1000, 2000, and 3000 kg ha⁻¹, respectively. A consistent relationship could be established between broomrape-infected sunflower yield, crop and broomrape biomass, and BIS parameters: SSY1 = 0.2259 x PoBio/(1 + 0.0687 x BIS) (r2 = 0.7820). The BIS economic threshold was about 1.5 and 3.5 for control treatment cost of $ 40 ha-1 and potential yields of 2000 and 1000 kg ha-1, respectively., Europen Union (EEC XII-TS2*0124-C) and the Spanish Scientific and Technological Commission (CICYT Agro-Petri 0057/92).

Referencia OEPM: P9402151.-- Fecha de solicitud: 14/10/1994.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).

Referencia OEPM: P9402152.-- Fecha de solicitud: 14/10/1994.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).

Despite the tremendous economic impact of broomrapes (Orobanche spp.) on agriculture in many countries little is known of the pattern of genetic variation within this group of parasitic weeds. The present paper describes the use of RAPD markers for the study of five Orobanche species in agricultural fields in Israel. Pronounced genetic differentiation was found between the species, and RAPD markers were raised for the identification of each of them. Southern-hybridization patterns of RAPD products of the various species were used to confirm the interpretation. The same markers were valid both for broomrapes collected in agricultural fields and for those collected in natural habitats. The validity of the markers found for O. cumana and O. crenata was confirmed on plants of the same species that were collected in Spain. Parsimony analysis of 86 RAPD characters produced a tree that clearly distinguishes between the five studied Orobanche species, separates the two Orobanche species belonging to sect. Trionychon from those belonging to sect. Osproleon, and supports the separation of O. cumana from O. cernua and of O. aegyptiaca from O. ramosa.

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