The effect of temperature and relative humidity on the airbone concentration of "Pyricularia oryzae" spores and the development of rice blast in southern Spain

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°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°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

Parasitismo del jopo (Orocanche Cernua, LOELF. (O. Cumana, Wallr)) en girasol (Helianthus annuus L.), su respuesta al glifosfato y cariabilidad isoenzimática intraespecífica

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Procedimiento de utilización del herbicida imazapir en semillas de siembra de lentejas para el control de la maleza parásita jopo (Orobanche crenata Forsk).

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

Procedimiento de utilización del herbicida propizamida en semillas de siembra de girasol para el control de la maleza parásita jopo (Orobanche cernua Loefl).

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

Procedimiento de utilización del herbicida imazetapir en semillas de siembra de guisantes para el control de la maleza parásita jopo (Orobanche crenata Forsk).

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

Certificado de adición de la patente no. 9402328. Procedimiento para el control de la maleza parásita Jopo (Orobanche cernua Loefl./O. cumana Wallr.) en el cultivo de girasol

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.Peer reviewe

Broad bean and lentil seed treatments with imidazolinones for the control of broomrape (Orobanche crenata)

8 pages, 2 figuresStudies 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.Peer reviewe

Uptake and translocation of imazethapyr in peas as affected by parasitism of Orobanche crenata and herbicide application methods

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.Peer reviewe

Competition of velvetleaf (Abutilon theophrasti M.) weed with cotton (Gossypium hirsutum L.): economic damage threshold

The effect of the weed Abutilon theophrasti M. (common name: velvetleaf) on the growth of cotton grown in the Guadalquivir Valley, was studied by examining the influence of weed density on growth of the weed and that of cotton. Velvetleaf impeded normal cotton growth caused production losses as a result of the stress the cotton was subjected to. Additionally there was competition among velvet leaf plants at high velvet leaf densities. The influence of velvetleaf density in coexistence with cotton has been also studied evaluating weed effect on the biomass of cotton and its production. Additional determinations included the velvetleaf seed production capacity per unit area and seed production per plant. These determinations were adjusted to hyperbolic, inverse linear and logistic models. Last, the economic damage threshold (EDT) was calculated using the efficiency level in control of velvetleaf in cotton. In this calculation the treatment cost and losses caused by the weed, in the crop, were taken into account. The EDT varied between 0.1- 0.5 velvetleaf plant m�2, depending on the control methods used.Se ha estudiado el efecto de Abutilon theophrasti M. (nombre común: abutilon) sobre el crecimiento del algodón en el Valle del Guadalquivir, examinando la influencia de la densidad de la mala hierba sobre su propio crecimiento y el del algodón. Abutilon theophrasti impidió el crecimiento normal del algodón y causó pérdidas de producción como consecuencia del estrés al que fue sometido. Además, se observó una reacción de competencia intraespecífica bajo condiciones de alta densidad de A. theophrasti. También se ha estudiado el efecto de la densidad de la maleza en el seno del algodón sobre su propia biomasa, la del algodón y su producción. Adicionalmente, se determinó la capacidad de producción de semillas de la mala hierba por superficie y la producción de semillas por planta. Estos valores fueron ajustados a modelos hiperbólicos, linear inversa y logística. Por último, se calculó el umbral económico de daños (EDT) utilizando los niveles de eficacia en el control químico de A. theophrasti en algodón. También se tuvo en cuenta el coste del tratamiento y las pérdidas de cosecha inducidas por la maleza. El EDT varió entre 0,1 y 0,5 plantas de A theophrasti m�2 dependiendo de la medida fitosanitaria utilizada en su control