La roya del sorgo

Four grain sorghum (Sorghum bicolor (L.) Moench.) lines showing distinct reactions to sorghum rust (Puccina purpurea Cooke) were planted under subhumid tropical oceanic conditions in northwestern Puerto Rico in an oxisol of pH 5.5 in May 1985. Disease development was periodically monitored until harvest. Rust levels were established using either no application or two applications each of either oxycarboxin, triadimefon or mancozeb fungicide. Noticeable rust was found at boot stage and increased with maturity. Rust differences were most apparent at physiological maturity. At that stage foliar rust coverage was estimated at 20, 16, 1 and 0% for SC 212, SC 307, TAM 428, and SC 120, respectively. Greatest rust control was found for oxycarboxin, triadimefon, and mancozeb in that order of efficacy. Oxycarboxin treatment resulted in over 80 and 60% less rust; 25 and 40% more grain yield; 0 and 20% greater seed density; and 80 and 71% more foliar sorghum anthracnose in SC 307 and SC 212, respectively, in comparison with those of nontreated plots. Fungicide treatments did not increase yields of either TAM 428 or SC 120, sorghum cultivare showing moderately resistant and very resistant rust reactions, respectively.La roya del sorgo causada por Puccinia purpurea Cooke causó pérdidas considerables en rendimiento de grano en 2 de 4 cultivares evaluadas en Isabela en 1985. Se establacieron diversas grados de severidad de la roya con diferentes fungicidas foliares con eficacia variable. Las líneas experimentales se seleccionaron por diferencia en resistencia. La epidemia de roya empezó en el estadio de hoja bandera y aumentó drásticamente después de la floración. Las diferencias de los tratamientos se notan más claramente en la maduración fisiológica. En esta etapa, la roya cubrió un 20, 16, 1 y 0% del follaje de SC 212, SC 307, TAM 428 y SC 120, respectivamente. Oxicarboxin fue el fungicida más eficaz contra la roya. Le siguieron triadimefon y mancozeb en ese orden. Al comparar los tratados con oxicarboxin con los sin tratar la roya disminuyó de 80 a 60%; el rendimento de grano aumentó 25 y 40% y la densidad de las semillas de 0 a 20% en las variedades de sorgo SC 307 y SC 212, respectivamente. Las variedades TAM 428, que es moderadamente resistente a la roya, y SC 120, que es muy resistente, no mostraron mejoría al tratarlas con los fungicidas

La roya del sorgo: II. Combate y pérdidas

Four sorghum lines of varying rust susceptibility, ranging from very resistant to susceptible, were planted in early September T985 in Isabela, Puerto Rico. Rust reactions were periodically evaluated from boot stage until grain harvest. At physiological maturity, foliar rust coverage was 24, 19, 7, and 0.5% for SC 212, SC 307, TAM 428, and SC 120, respectively. Four rust fungicide (oxycarboxin at 0.5 kg/ha/spray), applications at and after boot stage resulted m final rust coverage of 7, 3, 1, and 0% on SC 212, SC 307, TAM 428, and SC 120, respectively. Over all cultivars, one, two, and four applications gave 32.9, 73.7, and 85.4% rust control compared to the nontreated plots. In moderately and very resistant varieties (TAM 428 and SC 120), rust control was greater (74.5%) than that found in moderately and very susceptible ones (55.2% for SC 307 and SC 212). On SC 307 and SC 212, yield losses from rust were 29 and 50%, respectively. Reductions in 100-seed weights in SC 307 and SC 22 (28 and 41 %, respectively) approximated yield loss levels. Yield of SC 212 was superior to that of SC 307 when rust was controlled with oxycarboxin and inferior to that of SX 307 when rust was untreated. Moderately rust resistant TAM 428 showed no response to rust control despite 7% rust coverage. This same rust level reduced yield of the susceptible varieties. Because of the genotypic differences in rust-yield reactions, a generalized model relating visual rust coverage to plant performance appears inappropriate.En septiembre de 1985, se probaron líneas de sorgo que presentaron diferentes grados de susceptibilidad a la roya en Isabela, Puerto Rico. Durante la etapa de madurez fisiológica los porcentajes de área foliar afectada por la roya fueron 24, 19, 7 y 5 en las variedades SC 212, SC 307, TAM 428, y SC 120, respectivamente. Cuatro aplicaciones foliares de oxicarboxin (0.5 kg./ha.) durante la etapa de la hoja bandera y después de ella reprimieron la roya hasta obtenerse valores finales en porcentaje del área foliar afectada de 7, 3, 1 y 0, respectivamente, en las mismas variedades. Una, dos y cuatro aplicaciones reprimieron la roya en un 32.9, 73.7, y 85.4%, respectivamente, en estas cultivares. La eficacia de la represión química del patógeno fue mayor en variedades con alta o moderada resistencia a la roya (74.5%) si la comparamos con las variedades de moderada resistencia o de alta susceptibilidad (55.2%). La enfermedad redujo los rendimientos en 50 y 29% en las cultivares SC 212 y SC 307, respectivamente. Las respuestas en rendimiento al reprimir la roya fueron mayores en la variedad SC 212 que en la SC 307. El peso de 100 semillas disminuyó 41% y 28% en SC 212 y SC 307, respectivamente

Edades de corte e incidencia de enfermedades de dos sorgos forrajeros y sus rendimientos en materia seca y proteina bruta

Two forage sorghum hybrids ( ATx 623 X GL and FS25A) were grown from April 1985 to February 1987 at the Agricultural Experiment Station of the University of Puerto Rico at Lajas, Puerto Rico to determine the influence of maturity stage increases of 10 days (from the 45th to the 85th day) and how the presence and severity of foliar diseases affect the dry forage and crude protein yields. Dry matter content was higher for FS25A (16.1%) than for ATx 623 X GL (14.9%) whereas total yield for dry matter (DMY) was higher for ATx 623 X GL (3.84 t/ha) than for FS25A (3.51 t/ha). Both content and yield of dry matter increased with maturity stage in both genotypes. The sorghum hybrids did not differ significantly in crude protein content (CPC), but crude protein yield (CPY) was higher for ATx 623 X GL (421.6 kg/ha) than for FS25A (358.9 kg/ha). CPC declined with increased plant maturity. Foliar diseases appeared to limit DFY and CPY in both sorghum hybrids. Downy mildew, leaf blight, rust, grey leafspot, and zonate leafspot appeared seasonally. Leaf blight and downy mildew were the most prevalent from January to May, grey leafspot from May to September, and zonate leafspot from September to November. Rust was severe during all seasons.Se llevo a cabo un estudio con dos híbridos de sorgo forrajero (ATx 623 X GL y FS25A) de abril de 1985 a febrero de 1987 en la Subestación Experimental Agrícola de Lajas para medir la influencia sobre la producción de etapas de corte cada 10 días (desde el 45to al 85 to día) y como la incidencia de enfermedades afecta el rendimiento de forraje seco y proteína bruta. El contenido medio global de materia seca fue mayor en FS25A (16.1%) que en ATx 623 X GL (14.9). Lo contrario ocurrió con el rendimiento de forraje seco, ya que se obtuvo un rendimiento mayor con ATx 623 X GL (3.84 t./ha.) que con FS25A (3.51 t./ha.). El rendimiento de forraje seco y el contenido de materia seca aumentaron a medida que el forraje maduro. Las diferencias entre ambos híbridos en contenido medio de proteína bruta no fueron significativas. No obstante, la media ponderada para el rendimiento de proteína bruta total fue mayor para ATx 623 X GL (421.6 kg./ha.). El contenido y el rendimiento total de proteína bruta disminuyeron significativamente a medida que la etapa de corte aumentó de 45 a 85 días. Los rendimientos de forraje seco y de proteína bruta total también disminuyeron en ambos híbridos debido a la incidencia de enfermedades. Estas enfermedades fueron anublo lanoso ("downy mildew"), tizón ("leaf blight"), roya ("rust"), y mancha foliar ("zonate leafspot"). La época del año fue un factor determinante para la presencia de estas enfermedades. De enero a mayo la enfermedad más prevaleciente fue el anublo lanoso. Sin embargo, de mayo a julio predominó la mancha cercospórica y de septiembre a noviembre la mancha foliar

Impacts of Organic and Conventional Management on the Nutritional Level of Vegetables

The nutrient concentration of fruits and vegetables in the U.S.A. has declined in the past 50–70 years. Crop management practices utilizing on-farm inputs are thought to increase crop nutritional quality, but few studies have evaluated this under long-term side-by-side trials. An experiment was conducted from 2004 to 2005 at Rodale Institute’s long-term Farming Systems Trial to investigate the nutritional quality of vegetables under organic manure (MNR) and conventional (CNV) farming systems, with or without arbuscular mycorrhizal fungi (AMF) treatment. AMF reduced the vitamin C content in carrots in both systems in 2004, but the reduction was 87% in CNV and 28% in MNR. AMF also reduced antioxidants in carrots in both CNV and MNR. This trend was likely due to the suppression of native AMF colonization by the non-native AMF inoculum used. Between 2004 and 2005, MNR increased the vitamin C in green peppers by 50% while CNV decreased the vitamin C in red peppers by 48%. Tomatoes under MNR had a 40% greater vitamin C content compared to CNV in 2005. The vegetable yield declined between 2004 and 2005, except for tomato, where the yield increased by 51% and 44% under CNV and MNR, respectively. In general, MNR tended to increase the nutrient concentration of vegetables compared with CNV, while the AMF effects were inconclusive

Phomopsis Sojae: Colonization of Hosts, Interactions With Other Pathogens, and Losses on Soybeans

101 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1979.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

La roya del sorgo. III. Pérdidas en los híbridos bajo condiciones semiáridas

During the summer of 1986, experiments were conducted under semiarid conditions in Southwestern Puerto Rico to evaluate yield losses in grain sorghum inbred lines (TAM42B and SC307, moderately resistant and susceptible to rust, respectively) and forage sorghum hybrids (Haygrazer and FS25A, moderately and very susceptible to rust, respectively). A split plot design was used in which half of each plot was sprayed with triadimefon (0.5 kg/ha) at boot stage followed by an application of oxycarboxin (1.0 kg/ha) 2 weeks thereafter, and the other half was nontreated (control). In all sorghum entries, except TAM 428, yields increased significantly (P = 0.05) with fungicidal rust control over those of nontreated plots. When treated with triadimefon and oxycarboxin, FS25A, Haygrazer, and SC307 showed 23, 16, and 39% greater yield than respective nontreated plots. Rust control increased 100-seed weights over the nontreated controls by 19, 25, and 45% for the respective varieties. Nonsignificant increases in seed density (approximately 5%) were found in the fungicide treatment in ail lines. TAM 428, which did not respond to rust control, had over 75% functioning leaf area at physiological maturity (PM). In FS25A, Haygrazer, and SC307, all of which had less than 70% functioning leaf area remaining at PM, yield increased with increasing levels of functioning leaf area after fungicide treatment (r = 0.62*). Use of an eradicant nonpersistent rust fungicide (triadimefon) followed by a persistant systemic rust fungicide (oxycarboxin) gave excellent sorghum rust control during the critical stages for sorghum seed development. One-time use of different classes of fungicides should reduce development of fungicide resistant rust populations.Durante el verano de 1986 se realizaron experimentos de campo en la región semiárida del suroeste de Puerto Rico para determinar las pérdidas causadas por la roya en líneas de sorgo graníferos y forrajeros. Se utilizaron las líneas mejoradas para grano TAM428 y SC307, y los híbridos de sorgo forrajero Haygrazer y FS2SA, que son moderadamente susceptibles y muy susceptibles a la roya, respectivamente. Se usó un diseño de parcelas divididas; la mitad de cada parcela se asperjó con triadimefon (0.5 kg./ha.) en la época en que las plantas presentaban las hojas banderas y 2 semanas después se asperjó el follaje con oxycarboxin a razón de 1.0 kg./ha. La otra mitad de la parcela no se trató. En las líneas de sorgo utilizadas, excepto TAM428, los rendimientos aumentaron significativamente (P = 0.05) en FS25A (23%), Haygrazer (16%), y SC307 (39%), cuando las plantas se trataron con los fungicidas. Al controlar la roya, aumentaran los pesos de 100 semillas de FS25A (19%), Haygrazer (25%) y SC307 (45%) en relación a los testigos no tratados. Én todas las líneas de sorgo tratadas la densidad de las semillas aumentó en un 5% aproximadamente, pero no hubo diferencias significativas al compararlas con las no tratadas. No se observó respuesta al controlar la roya en la línea TAM428, la cual presentó un área foliar sana de 75% en su madurez fisiológica; mientras que Haygrazer, FS25A y SC307 presentaron menos de 70% de área foliar sana en su madurez fisiológica. Hubo una correlación significativa (r = 0.62*) entre el rendimiento de genotipos y el aumento del área foliar sana debido al tratamiento con fungicidas. El uso de un fungicida que erradique no persistente para la roya (triadimefon), seguido por un fungicida sistémico persistente (oxycarboxin) fue un excelente control de la roya durante los estados más críticos del desarrollo de la semilla de sorgo. El uso de diferentes clases de fungicidas para combatir la roya puede minimizar el riesgo de desarrollar poblaciones de roya con resistencia a los fungicidas con acción específica

Título en español.

Nine soybean cultivars (Buffalo, Cobb, Davis, Hardee Late Selection, IAC- 2, Improved Pelican, Jupiter, Orba, and Ransom) were planted at 11 dates from February 15, 1979 to October 1, 1979. At harvest maturity, the purple stained seeds from each of two 100-seed samples from each cultivar at each planting were counted. Variation in the incidence of purple seed was associated with cultivar and planting date. The highest overall incidences of purple seed were associated with Ransom (9.50%), Jupiter (8.27%); the lowest, in IAC-2 (0.29%), and Improved Pelican (0.23%). Precipitation and temperature levels were not associated with incidence of purple stain. Purple stain incidence was highly correlated with length of photoperiod at time of planting (r = -0.72); at 30 days after planting (r = - 0.97); and at 75 days after planting (r = -0.79). Shortened photoperiods appear to predispose soybean plants to purple stain. This fact may help explain the increased severity of purple stain in tropical areas compared with that in the temperate zones.La incidencia de la mancha púrpura de la soya se evaluó en nueve variedades comerciales que se sembraron en 11 fechas diferentes desde febrero a octubre de 1979 en Isabela, Puerto Rico. La mayor incidencia de semillas con la mancha púrpura apareció en las variedades "Ransom" (9.5%) y "Jupiter" (8.3%). Las variedades "IAC-2" (0.3%) e "Improved Pelican" (0.2%) mostraron los niveles más bajos de la mancha púrpura. No se observó correlación significativa entre los niveles de temperatura y lluvia y la incidencia de la mancha púrpura. Se observaron correlaciones negativas altas entre la incidencia de la mancha púrpura y el largo del fotoperíodo al momento de sembrar (r = -0.72), 30 días después de sembrar (r = 0.97) y a los 75 días después de sembrar (r = -0.79). Los fotoperíodos cortos aparentemente pueden predisponer las plantas de soya al ataque de la mancha púrpura. Esto puede explicar las incidencias altas de la mancha púrpura en áreas tropicales

RESISTANCE AND SCOUTING IN THE CONTROL OF YAM ANTHRACNOSE OF THE WINGED YAM (Dioscorea a fata )

Anthracnose (Colletotrichum gloeosporioides ) is a major obstacle to economic production of winged yams (D. alata ) in the Caribbean. We evaluated varietal resistance and disease scouting combined with fungicide for control of anthracnose. On Gunung, a high yielding introduction anthracnose severity never exceeded 15 % necrotic foliage and economic losses were not observed. Kinabayo and Kabusah were more anthracnose susceptible than Gunung but did not suffer economic losses. Binugas, a high yielding cultivar, has never shown over 25 % anthracnose losses detected once in 4 years. Florido, Forastero, and Leon Globe were always damaged with over 25 % yam anthracnose necrosis. Purmay, Gemelos, and Moresby were intermediately susceptible and usually showed yield and quality losses. Chemical control of anthracnose by preventive sprays required monthly applications (6 or more) during the rainy season. During 1986-87 and 1987-88, we tested the application of fungicide (benomyl + mancozeb) only when a 5 % increase in anthracnose over any month was found in susceptible varieties : no sprays were applied in 1987-88 in Mayaguez, and Isabela, and 3 sprays were applied in Isabella in 1986-87. Susceptible cultivars generally showed 15 % or more increase in tuber yield with fungicide protection. ----- L'Anthracnose (Colletotrichum gloeosporioides ) est un obstacle majeur à la production économique de l'igname ailée (D. alata ) dans la Caraïbe. Nous avons évalué la résistance variétale et l'évolution de la maladie associée à un fongicide dans la lutte contre l'anthracnose. Sur GUNNUNG, une introduction à haut rendement, l'attaque d'anthracnose ne dépasse jamais 15 % en nécrose du feuillage et il n'y a pas de réduction du rendement commercial. Kinabayo et Kabusah étaient plus sensibles mais ne présentaient pas de réduction de rendement commercial. BINUGAS, un cultivar à haut rendement, n'a jamais dépassé 25 % de nécrose due à l'anthracnose. PURMAN, GEMELOS et MORESBY de sensibilité intermédiaire éprouvaient généralement une perte de rendement et qualité. La lutte chimique contre l'anthracnose par pulvérisation préventive nécessite des traitements mensuels (6 ou davantage) pendant la saison des pluies. En 86-87 et 87- 88 nous avons testé l'application de bénomyl + mancozeb seulement quand on observait d'un mois au suivant un accroissement de 5 % de l'anthracnose chez les variétés sensibles : aucun traitement ne fut nécessaire à Mayaguez en 1986-87, deux le furent en 87-88 à Mayaguez et Isabela, et 3 furent faits à Isabela en 86-87. Les cultivars sensibles montrent généralement un accroissement de rendement de 15 % avec le traitement fongicide

Inducción de la floración, viabilidad del polen y la semilla e hibridación en yautías (Xanthosoma spp.)

Natural flowering and seed set in tanier (Xanthosoma spp.) is rare and limits improvement of the crop through hybridization. A study was conducted to induce uniform flowering with gibberelic acid (GA) in several species of Xanthosoma and to manually pollinate flowers to obtain true botanical seeds. Pollen and seed viability was also studied. Uniform flowering of plants was induced by foliar applications of a 500 mg/L solution of GA. Successful pollinations produced fruits that ripened in about 45 days and resulted in the production of 12 FT hybrid combinations and three selfed pollinations. Germination rates of tanier seeds always exceed 85% after a storage of more than 7 months at 8 ± °C and 80% relative humidity. Viability tests showed that pollen stored at 8 ± °C and 80% relative humidity could remain viable for about 8 days; however, the storage period was strongly dependent on pathogen interaction with the pollen grain.Se realizó un estudio para inducir con ácido giberélico la floración en varias especies de yautías y polinizar artificialmente las plantas para obtener semilla sexual. También se estudió la viabilidad del polen y las semillas. Se logró inducir la floración uniformemente entre especies mediante aplicaciones foliares de ácido giberélico a concentraciones de 500 mg./L.  Las polinizaciones produjeron frutas que maduraron en 45 días y se logró producir 12 híbridos F1 y tres autofecundaciones. El porcentaje de germinación de las semillas se mantuvo en más de 85% por 7 meses cuando las semillas se almacenaron a 8 ± °C a una humedad relativa de 80%. No obstante, la viabilidad del polen dependió grandemente de la presencia de patógenos en los granos de polen

Organic and Conventional Farming Systems: Environmental and Economic Issues.

Heavy agricultural reliance on synthetic-chemical fertilizers and pesticides is having serious impacts on public health and the environment. The estimated environmental and health care costs of the recommended use of pesticides in the U.S. are about $10 billion per year (Pimentel 2005). In the United States over 90 % of corn farmer