Isabel Calha

• Instituto Nacional de Investigação Agrária e Veterinária

Weeds management are the main crop protection issue in rice cultivation, responsible by about 30% of production losses in the field. Rice cultivation provides stability revenues to rural populations, in swamp ecosystems, wetlands, and lowlands, even in soils with high salinity, where other crops are not economic viable. To reduce yield losses, rice...

The decline of oak canopies in Iberian woodlands is strongly influenced by abiotic and biotic stress factors, such as the oomycete Phytophthora cinnamomi which has the capacity to infect a wide range of plant species. Understory plant diversity plays an important role in the epidemiology of P. cinnamomi in these ecosystems. This study aimed to iden...

The Weed Biology and Agroecology group (BAMh) of the Spanish Society of Weed Science (SEMh) is currently composed of 15 people working in 4 universities; Universitat de Lleida (UdL), Universitat Politècnica de València (UPV), Universidad de Sevilla (US) and Universitat Politècnica de Catalunya (UPC) and in 5 research centers in Spain and Portugal:...

Thirty years ago, the first case of resistance to herbicides was recorded in Portugal: Alisma plantago-aquatica resistant to bensulfuron-methyl in rice. Since then, herbicide resistance has been developing in many weed species. Changes in cultural practices, new cropping systems combined with the increased use of herbicides led to the selection of...

RESUMO Estudo sobre as perceções e as práticas culturais dos produtores de arroz na gestão de infestantes. Realizou-se um inquéri-to aos produtores, complementado com três reuniões (grupos focais) com técnicos e produtores. As infestantes identifica-das como as mais problemáticas foram as milhãs, seguidas pelo arroz-bravo. A leptocloa (erva-fina) c...

Weeds are the main phytosanitary problem in rice cultivation. Overreliance on herbicides and lack of diversity in rice growing operations has produced intense selection for the evolution of resistant weed populations. This study focused on rice farmers' perceptions and practices for weed management. The applied methodology was a questionnaire, carr...

A VEGETAÇÃO DOS MONTADOS EM ÁREAS AFETADAS POR DECLÍNIO

Flavescence dorée (FD) is considered a quarantine disease included in European legislation (Regulation (EU) 2019/2072) as it is one of the most serious phytosanitary problems affecting vineyards. It was detected in Portugal in 2007 (Sousa et al, 2007, 2010), in Portuguese cultivars, in the Cávado and Lima and rivers basins, in the heart of the “Vin...

Weeds are the main phytosanitary problem in rice crop. Over-reliance on herbicides and lack of crop operations range in the rice system have produced intense selection for the evolution of resistant weed populations. This study focused on rice farmers’ perceptions and attitudes towards weeds and agricultural practices for weed management. The metho...

The evolution of herbicide resistance in weeds has emerged as one of the most serious threats to sustainable food production systems, which necessitates the evaluation of herbicides to determine their efficacy. The first herbicide resistance case in the Iberian Peninsula was reported about 50 years ago, wherein Panicum dichotomiflorum was found to...

The variability in the emergence process of different populations was confirmed for two Echinochloa crus-galli populations, one from Italy (IT) and the second from Norway (NO). Seeds were sown in 12 localities over Europe and the Middle East and the emergence patterns of IT and NO were compared with those of several local populations at each locati...

Echinochloa crus‐galli (L.) P. Beauv. is one of the most important weeds. It is distributed worldwide and has adapted to diverse habitats and climatic conditions. This study aimed to compare the emergence patterns of two populations of E. crus‐galli from different environments at 11 locations across Europe and the Middle East. Seeds of the two popu...

The ability of three herbaceous plants (Diplotaxis tenuifolia (L.) DC., Eruca vesicaria L. and Raphanus raphanistrum L.) from Iberian wood pastures to reduce Phytophthora cinnamomi Rands pathogen populations through allelopathic relationships is studied. The inhibitory capacity of their aqueous root extracts (AREs) on mycelial growth and production...

Good weed management relies on the proper timing of weed control practices in relation to weed emergence dynamics. Therefore, the development of models that predict the timing of emergence may help provide growers with tools to make better weed management decisions. The aim of this study was to validate and compare two previously published predicti...

RESUMO Na cultura do arroz (Oryza sativa L.), realizada em constante alagamento, as infestantes que se desenvolvem, a sua densidade e correta gestão têm uma grande importância para o desenvolvimento do arroz e para a sua produção em quantidade e qualidade. O conhecimento da cultura, das infestantes e dos produtos herbicidas homologados permite rela...

Glyphosate resistance in Portugal was recently confirmed in Conyza bonariensis populations from intensive olive groves. This paper presents the results of a study to confirm glyphosate resistance in one population of C. bonariensis (B8) from a citrus orchard in the south of Portugal using a susceptible population as reference (C). Resistance was co...

The decline in Quercus suber (cork oak) and Q. rotundifolia (holm oak) “Montado” has been ascribed to the presence of the soil-borne pathogen Phytophthora cinnamomi. This oomycete has been considered a relevant agent related to the weakening and death of these oak species, both in Portugal and Spain (Extremadura and Andalucía). The control of this...

In Portugal a specific project aims to reduce the risk of “flavescence dorée” phytoplasma (FD) propagation in vineyards in order to increase the capacity to mitigate the severe FD damages. The project is applying more efficient monitoring tools, making use of eco-friendly technologies (smart traps) for automatic detection and identification of the...

Abutilon theophrasti is a weed that is spreading worldwide and that has had to adapt to different combinations of environmental conditions. Wide interpopulation variability has been reported regarding dormancy and germination. This variability, controlled by the interaction of genetic diversity and maternal effect, could hinder the adoption of Inte...

INTRODUÇÃO A produtividade do arroz é significativamente afectada pelo poten-cial da cultivar e pelo grau de competição das infestantes. Quarenta a 45 espécies infestam, em maior ou menor grau, os arrozais portu-gueses durante todo o seu ciclo (Catarino et al.,2005). Nos arrozais do Ribatejo as espécies infestantes mais importantes são o arroz-brav...

A resistant population of Conyza canadensis (L.) Cronq., (B15), was selected after several years of application of glyphosate from an intensive olive grove in Alentejo (south of Portugal). In order to study the hypothesis of target site resistance related to 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), shikimate leaf disc assay, sequencing...

Variability regarding dormancy and germination has been observed among some European populations of Datura stramonium L. Gradual adaptive processes to local environmental and agronomic conditions are supposed to be related to this intra-specific variability. Moreover, differences could exist among seeds batches produced by the same plants in differ...

Inter-population variability regarding dormancy and germination has been considered as part of the adaptive strategy of weeds to spread across areas with different environmental conditions or with frequent anthropic disturbances. Intra-specific variability has been observed among weed populations within the same climatic region as a consequence of...

Glyphosate is the most important and widely used herbicide in the world. In the Mediterranean area, the genus Lolium has developed resistance to glyphosate after decades of continued use without integrating alternative weed control practices in perennial crops (olive, citrus and vineyard). Oxyfluorfen alone or mixed with glyphosate and glufosinate...

A study on the spatial distribution of the major weeds in maize was carried out in 2007 and 2008 in a field located in Golegã (Ribatejo region, Portugal). The geo-referenced sampling focused on 150 points of a 10 x 10 m mesh covering an area of 1.5 ha, before herbicide application and before harvest. In the first year, 40 species (21 botanical fami...

Studies on weed germination are required to develop efficient integrated weed management strategies that should be transferable at wide scale and accurate at local level. To study interpopulation variability, which may hamper this process, three local populations of Datura stramonium were collected in Italy, Portugal and Spain and then cultivated s...

doi: 10.1614/WS-D-12-00162.1

Para confirmar a importância e distribuição do problema da resistência ao glifosato no Douro vinhateiro (norte de Portugal) fez-se uma prospecção em Julho de 2012 em 11 vinhas com colheita de sementes de Lolium spp. A espécie predominante em todas as vinhas era o Lolium perenne. Realizaram-se ensaios de dose-resposta com planta inteira, em estufa,...

En cultivos leñosos mediterráneos tales como el olivar y el viñedo, el uso al menos durante los últimos 15 años del glifosato en aplicación anual como método de escarda química ha seleccionado biotipos resistentes a este herbicida en diferentes especies de Lolium de la Península Ibérica, tales como Lolium rigidum (Gaudin) Weiss ex Nyman y Lolium mu...

In Portugal, glyphosate is widely used for weed control on perennial crops and non-cropping areas. It is considered an herbicide of high risk of resistance worldwide. Glyphosate resistance in Portugal was recently confirmed in Conyza bonariensis populations from intensive olive groves. This paper presents the results of a survey conducted for detec...

The insects present in the blackberry and blueberry crops are still almost unknown in Portugal. Thrips and their natural enemies were surveyed in these crops, during the flowering period, in Odemira region, as well as in the weeds inside and around the crops areas. This allows an evaluation of the entomological interaction cropweeds, for a future m...

Acarological surveys were carried out fortnightly from March to June 2011 on blackberries and weeds in a greenhouse at Fataca Experimental Farm in Odemira, in order to study species diversity and population interaction. This study focused on two blackberry cultivars, ‘Ouachita’ and ‘Karaka Black’. Sixteen mite species were identified on blackberrie...

Predictive empirical models of the timing of emergence were developed for ten major weed species in maize crops. Monitoring of seedling emergence was performed over two years in two maize fields located in Central Spain and Tagus Valley in Portugal. Thermal time was used as the independent variable for predicting cumulative emergence. Different non...

Evaluación de herbicidas para el control de avena silvestre ("Avena fatua"" L.) con resistencia a herbicidas que inhiben la acción de la enzima accasa en trigo en el valle de Mexicali, B.C.Manuel Cruz Villegas, Francisco Ponce Medina, Rubén Medina Martínez, Carlos Ceceña Durán, Jesús Santillano Cáceres, Leopoldo Partida Ruvalcaba, Francisco López L...

Propanil is the most important herbicide for rice weed management both at world and national level. Rice growers complains of poor control of Echinochloa was monitored in Mondego and Sorraia river valleys, Portugal. Seed samples were collected from the affected area and tested. After the first screening of 37 populations, the sensitivity of six Ech...

Seed germination of bensulfuron-methyl resistant (R) and susceptible (S) Alisma plantagoaquatica biotypes collected in rice fields from Baixo Mondego (6 samples); Sorraia river valey (2 samples) and Sado river valey (2 samples) were compared at 15 ºC and 15/30 ºC. All seed samples were two years old and an extra sample three years old was also incl...

The repetitive use of bensulfuron-methyl in rice fields from Sorraia, Sado and Mondego river valleys had selected resistant (R) populations of Alisma plantago-aquatica in Portugal, identified as So306, So307, Sa88, Mo190; Mo260, respectively. The response of R-biotypes to bensulfuron-methyl at 26 days after seeding (DAS) and 42 DAS and the crossres...

About 20 years ago the first case of herbicide resistance in the Iberian Peninsula was reported: Amaranthus spp. R to atrazine in Spanish orchards. Since then, herbicide resistance has evolved in many weed species. Changes on agricultural practices namely new tillage systems, new rotational programmes, combined with the increased use of herbicides...

Two Alisma plantago-aquatica biotypes resistant to bensulfuron-methyl were detected in rice paddy fields in Portugal’s Mondego (biotype T) and Tagus and Sorraia (biotype Q) River valleys. The fields had been treated with bensulfuron-methyl-based herbicide mixtures for 4–6 years. In order to characterize the resistant (R) biotypes, dose–response exp...

A consequence of modern agriculture and its dependence on herbicides, is the appearance of resistant weed populations. The first case of resistance on the Iberian Peninsula was found in Portugal and it was in a population of Alisma plantago-aquatica, resistant to bensulfuronmethyl, an ALS-inhibitor. For the same herbicide, control problems with Cyp...

The first known case of herbicide resistance found in Portugal occurred in the aquatic environment: populations of Alisma plantago-aquatica have shown resistance to bensulfuron-methyl. A large survey was carried out in 1996, covering 81% of the river valleys of Sado and Caia, 41% of Tagus and Sorraia and 26% of Mondego. In this survey, 164 fields w...