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Many types of symptoms associated with discolored grain have been observed on rice (Oryza sativa) sheaths, leaves, and grain in Mexico, Guatemala, Panama, Surinam, Colombia, Peru, and Brazil. These include brown necrotic lesions ranging from small specks to large brown to maroon sheath blotches. ...


Zeigler, Robert S.Álvarez, E.[Bacterial sheath brown rot of rice caused by Pseudomonas fuscovaginae in Latin America]Bacterial sheath brown rot of rice caused by Pseudomonas fuscovaginae in Latin America

In Venezuela, pedigree analyses indicate that the rice varieties currently under cultivation are closely related. Effective breeding programs, based on knowledge of the genetic diversity of cultivars, are needed to broaden the genetic bases of rice germplasm in the country. In this study, we used...


Ghneim-Herrera, ThauraPosso Duque, DPérez Almeida, I.Torrealba N., G.T.Pieters, AJMartínez Racines, César PompilioTohme, Joseph M.[Assessment of genetic diversity in Venezuelan rice cultivars using simple sequence repeats markers]Assessment of genetic diversity in Venezuelan rice cultivars using simple sequence repeats markers

Crosses were made between Fanny (highly susceptible to blast) and 11 cultivars differing in blast resistance. Using the pedigree method (PM) segregating generations were evaluated and selected for blast resistance. Via anther culture (AC), doubled-haploids were obtained from F1 plants and from F2...


Martínez Racines, César PompilioCorrea Victoria, Fernando J.Amézquita, María CristinaTulande Valencia, EdgarLema, GZeigler, Robert S.[Comparison of rice lines derived through anther culture and the pedigree method in relation to blast (Pyricularia grisea Sacc.) resistance]Comparison of rice lines derived through anther culture and the pedigree method in relation to blast (Pyricularia grisea Sacc.) resistance

The infection efficiency and the infection rate of the spore population of Pyricularia oryzae was lower if the percentage of races to which each cultivar was resistant was high. It appears that cultivars with resistance to a high percentage of the races of the pathogen behaved as expected for “ho...


Sang Won AhnOu, SH[Epidemiological implications of the spectrum of resistance to rice blast]Epidemiological implications of the spectrum of resistance to rice blast

Silicon (Si) has been shown to suppress diseases of rice such as blast when applied to Si-deficient soils. In 1995 and 1996, Si was applied at 1,000 kg ha-1 to at two locations in eastern Colombia to determine if Si combined with reduced rates of fungicide could be used to manage leaf and neck bl...


Seebold, KWDatnoff, LECorrea Victoria, Fernando J.Kucharek, TASnyder, GH[Effects of silicon and fungicides on the control of leaf and neck blast in upland rice]Effects of silicon and fungicides on the control of leaf and neck blast in upland rice

Protocols were established for screening rice genotypes for tolerance to water-limited conditions under field conditions. These protocols were successfully used to select the best genotypes for further experiments. Rice genotypes responded differently when subjected to water-limited conditions. E...


Sakai, TDuque E., Myriam CristinaVallejo Cabrera, Franco AlirioPompilio Martinez, CIshitani, Manabu[Establishment of drought screening protocols for rice under field conditions = Protocolo para la selección de genotipos de arroz tolerantes a déficit hídrico en campo]Establishment of drought screening protocols for rice under field conditions = Protocolo para la selección de genotipos de arroz tolerantes a déficit hídrico en campo

A new disease of rice, known as ‘entorchamiento’ (crinkling), was first noticed in the Department of Meta, Colombia, in 1991. Symptoms include seedling death, foliar striping and severe plant malformation. Tissue extracts and purified preparations from diseased rice plants, contained virus-like p...


Morales, Francisco JoséWard, ElaineCastaño, MauricioArroyave, José A.Lozano Potes, IvánAdams, Michael J.[Emergence and partial characterization of rice stripe necrosis virus and its fungus vector in South America]Emergence and partial characterization of rice stripe necrosis virus and its fungus vector in South America

Action thresholds for Tibraca limbativentris Stall (TL) on rice were calculated to be 8.8 and 25.8 TL per 10 sweep nets for 30- and 40-day old plants, respectively. Population dynamics of TL at two localities in Valle del Cauca, Colombia, indicated a density of 1.2 TL per sweep (12 TL per 10 swee...


Pantoja Lopez, ATriana Espinel, MónicaBastidas López, HaroldGarcía Ardila, C.Duque E., Myriam Cristina[Damage by Tibraca limbativentris (Hemiptera: Pentatomidae) to rice in Southwestern Colombia]Damage by Tibraca limbativentris (Hemiptera: Pentatomidae) to rice in Southwestern Colombia

The rice hoja blanca virus (RHBV), transmitted by the planthopper insect Tagosodes orizicolus, is a disease that attacks rice and generates significant production losses in Colombia. Fedearroz 2000 and Colombia I commercial rice varieties, which have different resistance levels to the disease, we...


Barrera, Nubia F.Melgarejo, Luz M.Cruz Gallego, MaribelCortés, Lina JimenaGuzmán, FannyCalvo, Julio C.[Conformationally Restricted Peptides from Rice Proteins Elicit Antibodies That Recognize the Corresponding Native Protein in ELISA Assays]Conformationally Restricted Peptides from Rice Proteins Elicit Antibodies That Recognize the Corresponding Native Protein in ELISA Assays

In the oldest sections of Burkina Faso's largest irrigation scheme in the Sourou Valley (13° 10′ N, 03° 30′W) rice (Oryza sativa L.) yields dropped from about 5 to 6 t ha−1 in the early 1990s, shortly after establishment of the scheme, to 2 to 4 t ha−1 from 1995 onwards. Farmers blamed this yield...


Asten, Piet J.A. vanBarro, S.Wopereis, M.Defoer, T.[Using farmer knowledge to combat low productive spots in an irrigated rice scheme in Burkina Faso]Using farmer knowledge to combat low productive spots in an irrigated rice scheme in Burkina Faso

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