A Survey for Diclofop-Methyl Resistance in Italian Ryegrass from Tennessee and How To Manage Resistance in Wheat

Italian ryegrass resistance to diclofop has been documented in several countries, including the United States. The purpose of this research was to screen selected putative resistant populations of Italian ryegrass for resistance to the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides diclofop and pinoxaden and the acetolactate synthase (ALS)-inhibiting herbicides imazamox, pyroxsulam, and mesosulfuron in the greenhouse and to use field experiments to develop herbicide programs for Italian ryegrass control. Resistance to diclofop was confirmed in eight populations from Tennessee. These eight populations did not show cross-resistance to pinoxaden. One additional population (R1) from Union County, North Carolina, was found to be resistant to both diclofop and pinoxaden. The level of resistance to pinoxaden of the R1 population was 15 times that of the susceptible population. No resistance was confirmed to any of the ALS-inhibiting herbicides examined in this research. Field experiments demonstrated PRE Italian ryegrass control with chlorsulfuron (71 to 94%) and flufenacet + metribuzin (84 to 96%). Italian ryegrass control with pendimethalin applied PRE or delayed preemergence (DPRE) was variable (0 to 85%). POST control of Italian ryegrass was acceptable with pinoxaden, mesosulfuron, flufenacet + metribuzin, and chlorsulfuron + flucarbazone (> 80%). Application timing and herbicide treatment had no effect on wheat yield, except for diclofop and pendimethalin treatments, in which uncontrolled Italian ryegrass reduced wheat yield.

Undersowing Italian ryegrass diminishes nitrogen leaching from spring barley

Selostus: Italian raiheinä aluskasvina vähentää typen huuhtoutumista ohranviljelyssä

Pasture characteristics of Italian ryegrass and milk production under different management strategies

The objective of this work was to assess the effects of the sward structure of Italian ryegrass (Lolium multiflorum), during the first grazing cycle, on its morphological and bromatological characteristics throughout the growing season, and on the performance of dairy cows. The treatments consisted of two structures obtained as a function of canopy-light interception: high-light interception (HLI) and low-light interception (LLI), with different pre-grazing heights in the first grazing cycle. Pasture was managed under rotational grazing with a herbage allowance not below 30 kg dry matter (DM) per cow per day. Three grazing cycles, with a grazing interval of 30 days, were evaluated. Pre-grazing herbage mass was greater (2,240 vs. 1,656 kg ha-1 DM), but the proportion of leaf blades was smaller (0.35 vs. 0.43) for HLI swards. Neutral detergent fiber (NDF) content and organic matter digestibility (OMD) were similar between treatments in the first grazing cycle, but in the second and third ones NDF was greater, and OMD lower, for the HLI swards. Milk yields were greater for cows grazing LLI swards (19.4 vs. 21.1 kg per day). Initial grazing with 90% of light interception promotes greater nutritional value in the subsequent cycles.

Verification of the mechanism of glyphosate resistance in Italian ryegrass biotypes.

The intense use of glyphosate for weed control led to the emergence of several cases of resistance to this herbicide. Weeds can survive the application of herbicides due to several factors, which may or may not be related to the herbicide site of action. The objectives of this study were to quantify the accumulation of shikimate in ryegrass biotypes in response to glyphosate application; investigate possible mutations on the EPSPs gene in susceptible and resistant biotypes; and evaluate the response of ryegrass biotypes to the application of glyphosate after treatment with a metabolism inhibitor of cyt P450 monooxygenase.

Resistance characterization of Italian ryegrass (Lolium multiflorum) biotypes to clethodim herbicide.

2016

Rapid assays for detection of glyphosate-resistant Lolium spp.

Diagnosing herbicide-resistant weed populations is the first step for herbicide resistance management. Monitoring the nature, distribution, and abundance of the resistant plants in fields demands efficient and effective screening tests. Different glyphosate resistant populations of Lolium multiflorum (VA) and L. rigidum (C) were used in assays for testing their effectiveness to detect herbicide resistance. According to a Petri dish bioassay 7 days after treatment (DAT), the VA and the C populations were 27 and 31 times more resistant to glyphosate than the susceptible populations, L. multiflorum (SM) and L. rigidum (SR), respectively. On a whole-plant bioassay (21 DAT), the VA and the C populations were 6 and 11 times more resistant to glyphosate than their respective susceptible populations. The susceptible populations accumulated 2.5 and 1.4-fold more shikimic acid 48 hours after treatment (HAT), than the resistant VA and C. Glyphosate gradually inhibited net photosynthesis in all populations but at 48-72 HAT the resistant plants recovered, whereas no recovery was detected in susceptible populations. All assays were capable of detecting the resistant populations and this may be useful for farmers and consultants as an effective tool to reduce the spread of the resistant populations through quicker implementation of alternative weed management practices. However, they differed in time, costs and equipments necessaries for successfully carrying on the tests. Regarding costs, the cheapest ones were Petri dish and whole-plant bioassays, but they are time-consuming methods as the major constraints are the collection of seeds from the field and at least some weeks to evaluate the resistance. The shikimic acid and net photosynthesis assays were the quickest ones but they demand sophisticated equipments which could restrict its use.

Doença alérgica polínica: polens alergógenos e seus principais alérgenos

Pacientes com alergia a pólen de gramíneas, comumente denominada polinose, freqüentemente apresentam reatividade a alérgenos de pólen de inúmeras gramíneas devido às reatividades cruzadas entre anticorpos IgE dirigidos contra proteínas presentes nos polens de gramíneas. Nesse contexto, pólen de Italian ryegrass (Lolium multiflorum), ou azevém anual, gramínea da família Poaceae cultivada no Sul do Brasil, é considerado o principal agente sensibilizante em pacientes com polinose. Nessa região, o azevém é capaz de produzir grande quantidade de pólen. Adicionalmente, outras gramíneas da família Poaceae crescem naturalmente no Sul, entretanto, sem relevância clínica. Extratos de pólen derivados de gramíneas homólogas ou heterólogas são freqüentemente empregados no diagnóstico e tratamento da alergia sazonal a pólen, sendo que para esses fins não se encontra comercialmente disponível no Brasil extrato padronizado de pólen de L. multiflorum. Futuros estudos serão importantes para melhor caracterizar a reatividade cruzada entre alérgenos de pólen de L. multiflorum e alérgenos de outras gramíneas com o objetivo de aprimorar o diagnóstico e imunoterapia de pacientes com alergia a pólen causada por L. multiflorum.

Soil aggregation in a crop-livestock integration system under no-tillage

Grazing intensities can influence soil aggregation, which can be temporarily and permanently affected. The objective of this study was to evaluate the aggregate stability in water at the end of a soybean cycle and during pasture development in a crop-livestock integration system under no-tillage and grazing intensities. The experiment was initiated in 2001, in a dystrophic Red Latosol, after soybean harvest. Treatments consisted of pasture (black oat + Italian ryegrass) at heights of 10, 20 and 40 cm, grazed by young cattle, and a control (no grazing), followed by soybean cultivation, in a randomized block design. Soil samples were collected at the end of the soybean cycle (May/2007), during animal grazing (September/2007) and at the end of the grazing cycle (November/2007). The grazing period influences aggregate distribution, since in the September sampling (0-5 cm layer), there was a higher proportion of aggregates > 4.76 mm at all grazing intensities. Soil aggregation is higher in no-tillage crop-livestock integration systems in grazed than in ungrazed areas.

Carbon and nitrogen cycling in an integrated soybean-beef cattle production system under different grazing intensities

Abstract:The objective of this work was to evaluate the effect of grazing intensity on the decomposition of cover crop pasture, dung, and soybean residues, as well as the C and N release rates from these residues in a long-term integrated soybean-beef cattle system under no-tillage. The experiment was initiated in 2001, with soybean cultivated in summer and black oat + Italian ryegrass in winter. The treatments consisted of four sward heights (10, 20, 30, and 40 cm), plus an ungrazed area, as the control. In 2009-2011, residues from pasture, dung, and soybean stems and leaves were placed in nylon-mesh litter bags and allowed to decompose for up to 258 days. With increasing grazing intensity, residual dry matter of the pasture decreased and that of dung increased. Pasture and dung lignin concentrations and C release rates were lower with moderate grazing intensity. C and N release rates from soybean residues are not affected by grazing intensity. The moderate grazing intensity produces higher quality residues, both for pasture and dung. Total C and N release is influenced by the greater residual dry matter produced when pastures were either lightly grazed or ungrazed.

Improving diquat efficacy on grasses by adding adjuvants to the spray solution before use

The effect of five adjuvants (non-ionic surfactant, paraffinic oil, vegetable oil, mixture of fatty acids methyl esters plus surfactant blend, and organosilicone) on diquat efficacy was assessed on poverty brome, sterile oat, and Italian ryegrass in field and pot experiments. All tank mixtures with diquat increased diquat efficacy from 50-54% to 77-98% as for fresh weight reduction, indicating significant enhancement of diquat efficacy on grasses. The increased efficacy was most likely attributed to better droplet retention and diffusion on the leaf surfaces. When combined with non-ionic surfactant, diquat showed slightly more rapid control of grass weeds (i.e. symptoms were visible within a few hours after application).

Die mikrobielle Besiedlung von Wurzeloberfläche und Rhizosphäre in ihrer Bedeutung für Stoffumsätze in Böden

Im Vordergrund der Arbeit stand die Erfassung der mikrobiellen Biomasse bzw. Residualmasse an der Wurzeloberfläche, im Rhizosphärenboden und im umgebenden Boden. Durch den Vergleich von verschiedenen Methoden zur Erfassung der mikrobiellen Biomasse wurden die Gehalte von pilzlichem und bakteriellem Kohlenstoff an der Rhizoplane und in der Rhizosphäre quantifiziert. Dabei wurde die Fumigations-Extraktions-Methode zur Erfassung der mikrobiellen Biomasse eingesetzt. Ergosterol diente als Indikator für die pilzliche Biomasse und die Aminozucker Glucosamin und Muraminsäure sollten Aufschluss geben über die bakterielle und pilzliche Biomasse bzw. Residualmasse in den drei Probenfraktionen. Dazu wurden Umrechnungsfaktoren erstellt, die zur Berechnung des bakteriellen und pilzlichen Kohlenstoffs aus den Gehalten von Muraminsäure und Pilz-Glucosamin dienten. Die Bestimmung von Aminozuckern wurde insoweit modifiziert, dass sowohl in Boden- als auch in Wurzelhydrolysaten die Messung von Glucosamin, Galactosamin, Muraminsäure und Mannosamin gleichzeitig als automatisiertes Standardverfahren mit Hilfe der HPLC erfolgen konnte. Es wurden drei Gefäßversuche durchgeführt: Im ersten Versuch wurde der Einfluss der Pflanzenart auf die mikrobielle Besiedlung der Wurzeloberflächen untersucht. Dabei wurden Wurzeln und Rhizosphärenboden von 15 verschiedenen Pflanzenarten miteinander verglichen. Im zweiten Versuch stand der Einfluss der mikrobiellen Biomasse eines Bodens auf die mikrobielle Besiedlung von Wurzeloberflächen im Vordergrund. Deutsches Weidelgras (Lolium perenne L.) wurde auf sieben verschiedenen Böden angezogen. Bei den Böden handelte es sich um sechs Oberböden, die sich hinsichtlich des Bodentyps und der Bewirtschaftungsform voneinander unterschieden, und einen Unterboden. Im dritten Versuch wurde die mikrobielle Besiedlung von Wurzeln nach teilweiser und vollständiger Entfernung der oberirdischen Biomasse beobachtet. Welsches Weidelgras (Lolium multiflorum Lam.) wurde 24 Tage nach der Aussaat beschnitten. Anschließend wurde über einen Versuchszeitraum von acht Tagen die mikrobielle Besiedlung an den Wurzeln und in den Bodenfraktionen bestimmt. Es bestätigte sich, dass der Einfluss der einzelnen Pflanzenart von entscheidender Bedeutung für die mikrobielle Besiedlung von Wurzeln ist. Bei fast allen Pflanzen wurde die mikrobielle Biomasse an den Wurzeln von Pilzen dominiert. Das Verhältnis von pilzlichem zu bakteriellem Kohlenstoff an den Wurzeln der 15 Pflanzenarten lag im Mittel bei 2,6. Bei der Betrachtung verschiedener Böden zeigte sich, dass die mikrobielle Besiedlung in tieferen Bodenschichten signifikant niedriger ist als in den Oberböden. Dabei war der Pilzanteil an der mikrobiellen Biomasse im Unterboden deutlich erhöht. Der Vergleich der Oberböden untereinander ergab, dass sowohl der Bodentyp als auch die Bewirtschaftungsform einen signifikanten Einfluss auf mikrobielle Besiedlung ausüben. Durch die teilweise oder vollständige Entfernung der oberirdischen Biomasse wurde eine Veränderung der mikrobiellen Besiedlung an den Wurzeln beobachtet. Das Verhältnis von pilzlichem zu bakteriellem Kohlenstoff sank in dem Versuchszeitraum von 2,5 auf 1,4. Dabei war die Förderung der Pilze in der Variante mit teilweise entfernter oberirdischer Biomasse relativ größer als in der Variante mit vollständig entfernter oberirdischer Biomasse. Entgegen der weit verbreiteten Annahme, dass bei den wurzelbesiedelnden Mikroorganismen die Bakterien gegenüber den Pilzen dominieren, zeigten die Ergebnisse ein gegensätzliches Bild. In allen drei Versuchen ergab sich gleichermaßen, dass sowohl im Boden als auch an den Wurzeln die Pilze gegenüber den Bakterien dominieren.

Soil bacterial phoD gene abundance and expression in response to applied phosphorus and long-term management

Bacterial transformation of phosphorus (P) compounds in soil is largely dependent on soil microbial community function, and is therefore sensitive to anthropogenic disturbances such as fertilization or cropping systems. However, the effect of soil management on the transcription of bacterial genes that encode phosphatases, such as phoD, is largely unknown. This greenhouse study examined the effect of long-term management and P amendment on potential alkaline phosphatase (ALP) activity and phoD gene (DNA) and transcript (RNA) abundance. Soil samples (0–15 cm) were collected from the Glenlea Long-term Rotation near Winnipeg, Manitoba, to compare organic, conventional and prairie management systems. In the greenhouse, pots of soil from each management system were amended with P as either soluble mineral fertilizer or cattle manure and then planted with Italian ryegrass (Lolium multiforum). Soils from each pot were sampled for analysis immediately and after 30 and 106 days. Significant differences among the soil/P treatments were detected for inorganic P, but not the organic P in NaHCO3-extracts. At day 0, ALP activity was similar among the soil/P treatments, but was higher after 30 days for all P amendments in soil from organically managed plots. In contrast, ALP activity in soils under conventional and prairie management responded to increasing rates of manure only, with significant effects from medium and high manure application rates at 30 and 106 days. Differences in ALP activity at 30 days corresponded to the abundance of bacterial phoD genes, which were also significantly higher in soils under organic management. However, this correlation was not significant for transcript abundance. Next-generation sequencing allowed the identification of 199 unique phoD operational taxonomic units (OTUs) from the metagenome (soil DNA) and 35 unique OTUs from the metatranscriptome (soil RNA), indicating that a subset of phoD genes was being transcribed in all soils.

Surto de polioencefalomalacia por ingestão excessiva de enxofre na dieta em bezerros no Rio Grande do Sul

Neste trabalho descreve-se surto de polioencefalomalacia em bovinos decorrente da ingestão de dieta com excessiva concentração de enxofre em uma propriedade no Rio Grande do Sul. O lote era composto por 30 bezerros, mantidos em um piquete com azevém (Lolium multiflorum) e suplementados com ração e sal mineral. Seis bezerros morreram e dois deles foram necropsiados; amostras de tecido hepático para dosagem de chumbo e fragmentos do sistema nervoso central para histopatológico foram colhidos. Um dos bezerros foi examinado antes da morte e sinais neurológicos encefálicos foram constatados. Foi estabelecido o teor de enxofre nos componentes da dieta e água, a produção de sulfeto de hidrogênio ruminal em cinco bovinos do mesmo lote e realizada PCR de um bloco de parafina para detecção de DNA do herpevirus bovino tipo 5. O consumo total de enxofre foi de 0,38% da matéria seca fornecida aos animais e as dosagens de sulfeto de hidrogênio ruminal em animais do mesmo lote variaram de 1.000 a 2.500ppm. Os achados histopatológicos indicaram necrose laminar do córtex cerebral. Não foi detectado chumbo na amostra de tecido hepático e não foi identificado DNA do herpesvirus bovino tipo 5 no encéfalo. O quadro clínico de síndrome cerebrocortical associado aos elevados valores do sulfeto de hidrogênio ruminal, alta ingestão de enxofre na dieta e os achados histopatológicos permitem estabelecer o excesso de enxofre como causador da polioencefalomalacia.

Carcaças e componentes não-carcaça de cordeiros terminados em pasto de azevém recebendo suplementação concentrada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Produção de bovinos de corte em pastagem de aveia preta e azevém submetida à adubação nitrogenada

We evaluated animal production on black oats (Avena strigosa Schreb.) and italian ryegrass (Lolium multiflorum) pasture submitted to nitrogen top fertilization of 0; 150 and 300 kg ha-1, in the form of urea. We used 36 calves with average age and average weight of 10.5 months and 180 kg, respectively, as test-animals. The grazing system used was continuous with variable stocking rate. The block design was completely randomized with three replicates (paddock). Average weight gain was similar for the levels evaluated (0.925; 0.969 and 1.045 kg day-1, respectively). Stocking rate and live weight gain per hectare showed a linear relation with nitrogen levels. The efficiency of animal production was 2.040 and 1.766 kg of weight gain per kg of nitrogen used for the dose of 150 and 300 of N, respectively. The stocking rate and live weight gain per hectare of beef calves increased with the nitrogen levels, from 0 to 300 kg of N ha-1. However, the best efficiency in weight gain per unit of nitrogen applied was obtained with the dose of 150 kg of N ha-1.