996 resultados para late season diseases
Resumo:
Experiments were conducted to investigate the effect of Lolium rigidum (annual ryegrass) seed developmental stage and application rate of glyphosate and SpraySeed (paraquat 135 g/L+ diquat 115 g/L) on the number, germinability, and fitness of seeds produced. Glyphosate (450 g/L) was most effective when applied at a rate of 0.5-1 L/ha during heading and anthesis, reducing the number of filled seeds produced compared with unsprayed plants. Application post-anthesis, when seeds were at the milk to soft dough stage, was less effective. SpraySeed was most effective when applied post-anthesis, during the milk and early dough stages of seed development at a rate of 0.5-1L/ha, resulting in the production of few viable seeds. Although some filled seeds were produced, most of the seeds were dead. Application during anthesis or once the seeds reached soft dough stage was less effective. For both herbicides, those seeds that were capable of germinating were smaller and had slower radicle and coleoptile growth, resulting in slower early seedling growth and reduced biomass production within the first month of growth. Additionally, glyphosate application reduced the proportion of seeds exhibiting dormancy. The anticipated reduction in seed competitive ability and altered emergence timing resulting from late-season herbicide application, even when application timing is not optimal, could be exploited to reduce the likelihood of successful L. rigidum establishment in the following season.
Resumo:
The aim of this work was to investigate differences among genotypes in post-anthesis root growth and distribution of modern UK winter wheat cultivars, and the effects of fungicide applications. Post-anthesis root growth of up to six cultivars of winter wheat (Triticum aestivum L.), given either one or three applications of fungicide, was studied in field experiments during two seasons. Total root mass remained unchanged between GS63 (anthesis) and GS85, but root length increased significantly from 14.7 to 31.4 km m(2) in one season. Overall, there was no evidence for a decline in either root mass or length during grain filling. Root mass as a proportion of total plant mass was about 0.05 at GS85. There were significant differences among cultivars in root length and mass especially below 30 cm. Malacca had the smallest root length and Savannah the largest, and Shamrock had a significantly larger root system below 40 cm in both seasons. Fungicide applied at ear emergence had no significant effect on root mass in either season but increased root length (P < 0.01) in the more disease-prone season. By maintaining a green canopy for longer, fungicide applied at flag leaf emergence may have resulted in delayed senescence of the root system and contributed to the post-anthesis maintenance of root mass and length.
Resumo:
Field experiments were conducted over 3 years to study the effect of applying triazole and strobilurin fungicides on the bread-making quality of Malacca winter wheat. Averaged over all years the application of a fungicide programme increased yields, particularly when strobilurin fungicides were applied. Reductions in protein concentration, sulphur concentration, Hageberg failing number and loaf volumes also occurred as the amount of fungicide applied increased. However, there were no deleterious effects of fungicide application on sodium dodecyl sulphate (SDS) sedimentation volumes, N:S ratios or dough theology. Effects of fungicide application on bread-making quality were not product specific. Therefore, it appears that new mechanisms to explain strobilurin effects on bread-making quality do not need to be invoked. Where reductions in protein concentration did occur they could be compensated for by a late-season application of nitrogen either as granular ammonium nitrate at flag leaf emergence or foliar urea at anthesis. These applications, however, sometimes increased the N:S ratio of the extracted flour and failed to improve loaf volume. Multiple regression analysis revealed that main effects of year, flour protein concentration and N:S ratio could explain 93% of the variance in loaf volume caused by season, fungicide and nitrogen treatments. However, an equally good fit was achieved by just including sulphur concentration with year. (C) 2004 Elsevier Ltd. All rights reserved.
Resumo:
Field experiments were conducted over 3 years to study the effect of applying triazole and strobilurin fungicides on the bread-making quality of Malacca winter wheat. Averaged over all years the application of a fungicide programme increased yields, particularly when strobilurin fungicides were applied. Reductions in protein concentration, sulphur concentration, Hageberg failing number and loaf volumes also occurred as the amount of fungicide applied increased. However, there were no deleterious effects of fungicide application on sodium dodecyl sulphate (SDS) sedimentation volumes, N:S ratios or dough theology. Effects of fungicide application on bread-making quality were not product specific. Therefore, it appears that new mechanisms to explain strobilurin effects on bread-making quality do not need to be invoked. Where reductions in protein concentration did occur they could be compensated for by a late-season application of nitrogen either as granular ammonium nitrate at flag leaf emergence or foliar urea at anthesis. These applications, however, sometimes increased the N:S ratio of the extracted flour and failed to improve loaf volume. Multiple regression analysis revealed that main effects of year, flour protein concentration and N:S ratio could explain 93% of the variance in loaf volume caused by season, fungicide and nitrogen treatments. However, an equally good fit was achieved by just including sulphur concentration with year. (C) 2004 Elsevier Ltd. All rights reserved.
Resumo:
Late-season grapefruits (Citrus paradisi Macf. cv. Marsh seedless) were dipped in water at 50°C for 3 min with and without 200 ppm imazalil (IMZ) or 1000 ppm IMZ at 19°C and were subsequently stored at 7°C and 90-95% relative humidity (RH) for 11 weeks plus one week at 21°C and approximately 75% RH to simulate a marketing period (SMP). Residue concentrations in fruit after treatment with 200 ppm IMZ at 50°C were 3.46 ppm, about twice the level (1.80 ppm) found in fruit treated with 1000 ppm IMZ at 19°C. Fungicide degradation rates during storage showed similar patterns resulting in an approximately 50% decrease. Both fungicide treatments significantly reduced decay and chilling injury (CI) during storage and SMP. Hot water reduced CI and decay but not as effectively as the IMZ treatments. Soluble solids concentrations were not affected by treatments, IMZ treatments resulted in significantly lower values of titratable acidity and higher concentrations of ethanol in the juice after SMP. Weight loss was significantly higher in fruit dipped in water at 50°C after SMP. No visible damage occurred to the fruit as a result of any of the treatments.
Resumo:
Fungal fruit rots and insect pests are among the most important problems negatively affecting the yield and quality of mid-Atlantic wine. In pathogenicity trials of fungi recovered from diseased Chardonnay and Vidal blanc grapes, Alternaria alternata, Pestalotiopsis telopeae, and Aspergillus japonicus were found to be unreported fruit rot pathogens in the region. Additionally, P. telopeae and A. japonicus had comparable virulence to the region’s common fruit rot pathogens. Furthermore, a timed-exclusion field study was implemented to evaluate vineyard insect-fruit rot relationships. It was found that clusters exposed to early-season insect communities that included Paralobesia viteana had a significantly greater incidence of sour rot than clusters protected from insects all season. These results were contrary to the current assumption that fall insects are the primary drivers of sour rot in the region. This research provides diagnostic tools and information to develop management-strategies against fungal and insect pests for mid-Atlantic grape growers.
Resumo:
The objective of this study was to determine the effects in the yield of soybean crop utilizing a trailing boom sprayer for chemical control of late season diseases. The experimental design was randomized blocks with 04 treatments, which consisted of applying fungicides with a traditional sprayer, trailing boom, the traditional sprayer plus the trailing boom simultaneously and control (without fungicide aerial application) in 05 repetitions per treatment. The variables evaluated were: final plant population, pods per plant, grains per pod, weight of one thousand grains and yield. It was concluded that the control of foliar diseases with fungicides presented weight of one thousand grains and yield significantly higher than the average of plots without fungicide application. The trailing boom did not significantly affect the yield compared to the technology currently used.
Resumo:
The fungus Rhizoctonia solani AG-1 IA causes sheath blight, one of the most important rice diseases worldwide. The first objective of this study was to analyse the genetic structure of R. solani AG-1 IA populations from three locations in the Iranian Caspian Sea rice agroecosystem. Three population samples of R. solani AG-1 IA isolates were obtained in 2006 from infected rice fields separated by 126-263km. Each field was sampled twice during the season: at the early booting stage and 45days later at the early mature grain stage. The genetic structure of these three populations was analysed using nine microsatellite loci. While the population genetic structure from Tonekabon and Amol indicated high gene flow, they were both differentiated from Rasht. The high gene flow between Tonekabon and Amol was probably due mainly to human-mediated movement of infested seeds. The second objective was to determine the importance of recombination. All three populations exhibited a mixed reproductive mode, including both sexual and asexual reproduction. No inbreeding was detected, suggesting that the pathogen is random mating. The third objective was to determine if genetic structure within a field changes over the course of a growing season. A decrease in the proportion of admixed genotypes from the early to the late season was detected. There was also a significant (P=0·002) increase in the proportion of loci under Hardy-Weinberg equilibrium. These two lines of evidence support the hypothesis that basidiospores can be a source of secondary inoculum. © 2012 BSPP.
Early season ozone uptake is important for determining ozone tolerance in two trembling aspen clones
Resumo:
There is substantial genetic variability in response to ozone amongst and within tree species. Aspen is a highly variable species with a wide range of responses to ozone. Aspen response to elevated O3 levels is being investigated at the Aspen FACE site near Rhinelander, WI where five aspen clones of varying O3 tolerance have been fumigated with elevated O3 over the past decade. In this study, we examined the physiological differences in two of the aspen clones that differed significantly in their O3 tolerance with 8L being tolerant and 42E being sensitive. Throughout the 2007 and 2008 growing seasons we periodically estimated instantaneous photosynthetic rates, ACi responses and light response curves. The results of our study suggest that aspen clone 8L’s tolerance is due in part to decreased stomatal conductance early in the season, which lowered ozone uptake. Later during the season O3 uptake was comparable for the two clones. Our results also suggest the response of Vcmax, TPU, Rd, Gm, light compensation point and quantum flux to elevated O3 did not differ significantly between the two clones. Ozone uptake is important for ozone tolerance in clone 8L early in the season but cannot explain late season tolerance. Photosynthetic parameters for the two clones were similar, so clone 8L’s ozone tolerance is not due to a more efficient photosynthetic system.
Resumo:
Experiments to evaluate the effect of in-season calcium (Ca) sprays on late-season peach (Prunus persica L. Batsch cv. Calrico) were carried out for a 2-year period. Calcium formulations (0.5% and 1.0% in 2008 and only 0.5% tested in 2009) supplied either as CaCl2 or Ca propionate in combination with two or three adjuvants (0.05% of the nonionic surfactants Tween 20 and Break Thru, and 0.5% carboxymethylcellulose, CMC) were sprayed four to five times over the growing season. Peach mesocarp and endocarp Ca concentrations were determined on a 15-day basis from the beginning of May until the end of June. Further tissue analyses were performed at harvest. A decreasing trend in fruit Ca concentrations over the growing season was always observed regardless of the Ca treatments. Both in 2008 and 2009, significant tissue Ca increments associated with the application of Ca-containing sprays in combination with adjuvants were only observed in June, which may be coincident with the period of pit hardening. In 2008, both at harvest and after cold storage, the total soluble-solids concentration (° Brix) of fruits supplied with Ca propionate (0.5% and 1.0% Ca) was always lower as compared to the rest of treatments. The application of multiple Ca-containing sprays increased firmness at harvest and after cold storage, especially when CaCl2 was the active ingredient used. Supplying the adjuvants Tween 20 and CMC increased fruit acidity both at harvest and after cold storage. Evaluation of the development of physiological disorders after cold storage (2 weeks at 0°C) indicated a lower susceptibility of Ca-treated fruits to internal browning. Fruits treated with multiple CaCl2-, CMC-, and Break Thru®-containing sprays during the growing season were significantly less prone to the development of chilling injuries as compared to untreated peaches.
Resumo:
Silverleaf whitefly (SLW) is a major late season pest of cotton due to its potential to contaminate cotton lint with honeydew. To prevent this, management is often reliant on the use of insecticides to control SLW populations. With selection pressure SLW develop resistance to insecticides they are exposed to, resulting in spray failures. Our lab tests resistance levels in SLW populations collected from across the cotton industry. In this presentation I will provide an update of emerging SLW resistance issues the cotton industry is facing.
Resumo:
This report was prepared as part of the Project “Monitoring Influenza vaccine effectiveness during influenza seasons and pandemics in the European Union” and describes the results obtained in Portugal under the Protocol Agreement celebrated between EpiConcept SARL, Paris and National Health Institute Dr. Ricardo Jorge, Lisbon. Data and activities related to the individuals 65 years and more were funded by European Union’s Horizon 2020 research and innovation programme under grant agreement no 634446.
Resumo:
ABSTRACT: Asian soybean rust, caused by the fungus Phakopsora pachyrhizi, is the most severe disease of the crop and can cause yield losses of up to 90%. The disease was first reported in Brazil in 2001. Epidemics of the disease are common in the country, where the fungus can survive year?round. Regulatory measures to reduce the inoculum between seasons and avoid late-season soybean have been adopted to manage the disease. Disease control has relied mainly on chemical control, but a lower sensibility of the fungus to fungicides has been reported in Brazil. Major?resistance genes have been mapped and incorporated into the cultivars. With the reduced efficacy of the fungicides, the adoption of integrated measures to control the disease will be important for the sustainability of the crop. This review presents the main changes in the soybean crop system caused by the introduction of the fungus in Brazil, the current management strategies adopted to avoid losses, and the new trends that, together with biotechnological strategies, can improve management in the future. RESUMO: A ferrugem?asiática da soja, causada pelo fungo Phakopsora pachyrhizi, é a doença mais severa da cultura e pode causar perdas de produtividade de até 90%. A doença foi relatada pela primeira vez no Brasil em 2001. Epidemias da doença são comuns no País, onde o fungo pode sobreviver durante todo o ano. Medidas regulatórias para reduzir o inóculo entre safras e evitar a semeadura tardia de soja têm sido adotadas para manejar a doença. O controle da doença tem se baseado principalmente no controle químico, mas uma menor sensibilidade do fungo aos fungicidas tem sido relatada no Brasil. Genes de resistência têm sido mapeados e incorporados às cultivares. Por causa da redução da eficiência dos fungicidas, a adoção de medidas integradas para o controle da doença será importante para a sustentabilidade da cultura. Este artigo de revisão apresenta as principais mudanças no sistema de produção da soja causadas pela introdução do fungo no Brasil, as medidas de controle atualmente usadas para evitar perdas, e as novas tendências que, juntas com estratégias biotecnológicas, podem melhorar o manejo da doença no futuro.
Resumo:
Elite athletes repeatedly completed the Profile of Mood States (POMS) during a six month training season to determine whether athletes who are stale show different values from those who are intensely trained but not stale. Nineteen elite male and female swimmers were studied at five time points: three times during training (early-, mid-, and late-season), during tapering prior to, and then shortly after, major competition. Of the 14 subjects who completed the entire monitoring program, three were classified as stale based on several criteria including poorer performance and prolonged high level of fatigue. Two of the stale swimmers showed higher scores for several of the POMS measures throughout the season compared with the remainder who were classified as non-stale. However, the third stale swimmer showed similar scores to those of the non-stale swimmers. Several POMS measures were significantly correlated with training intensity but not with training volume. It was concluded that stale athletes may not always demonstrate different mood scores from non-stale athletes but that the total mood disturbance score (TMD) as evaluated by the POMS may be used to indicate those athletes predisposed to the condition long before the symptoms of poor performance and prolonged fatigue are observed. TMD scores were chosen to monitor staleness since they represent a synthesis of the six specific mood states measured by the POMS.