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A resistência de plantas daninhas é um grande problema que afeta a produtividade das culturas em nosso país, ao passo que quando é identificada, deve ser estudada visando desenvolver estratégias de manejo que evitem a expansão e seleção em novas áreas, além de seleção de resistência múltipla em áreas onde está presente. Nesta temática o objetivo desta pesquisa foi determinar manejo alternativo ao glyphosato para as espécies Chloris elata e Digitaria insularis no período de entressafra da cultura da soja e identificar características morfológicas da superfície foliar de Chloris elata que possam interferir sobre o controle com herbicidas. Foram estudadas alternativas ao glyphosate para manejo em áreas de sistema de produção soja/milho, em dois experimentos com as plantas daninhas Chloris elata e Digitaria insularis perenizadas e com duas condições de roçada (15 e 30 cm). Foram avaliados o controle visual das plantas daninhas, redução de matéria fresca e seca. Para morfologia das folhas da espécie Chloris elata foi realizada análise histológica com recursos de microscopia eletrônica de varredura, visando caracterizar a morfologia da folha, além de determinar o índice estomático, densidade estomática e densidade de tricomas para as superfícies adaxial e abaxial das folhas, nos estádios 4 e 6 folhas totalmente expandidas. Digitaria insularis se mostrou menos suscetível as técnicas de manejo empregadas para plantas perenizadas, necessitando duas aplicações sequenciais para conter a rebrota dos tratamentos. O uso da maior dose do herbicida haloxyfop associado aos herbicidas glyphosate ou amônio-glufosinato se mostrou eficaz no controle de C. elata e D. insularis. O manejo de roçagem potencializou a ação dos herbicidas, e a planta daninha D. insularis se mostrou mais suscetível a está técnica em relação ao C. elata. Para este manejo a associação da maior dose de haloxyfop ao glufosinato foi eficaz para as duas gramíneas. As alturas de roçagem somente se diferenciaram nas primeiras avaliações. O biótipo resistente de C. elata apresentou menor densidade estomática, no estádio de 4 folhas completamente expandidas e maior densidade de tricomas no estádios de 6 folhas completamente expandidas, o que pode contribuir para a resistência ao glyphosate. Está espécie apresentou formações de cristais de cera que circundam o ostíolo, no estádio de 6 folhas completamente expandidas, podendo estar relacionada a a menor suscetibilidade ao glyphosate desta planta daninha perenizada. / Weed resistance is a major problem that affects crop productivity in our country, whereas when it is identified, it must be studied in order to develop management strategies that avoid expansion and selection in new areas, as well as multiple resistance selection in areas where it is present. In this subject the objective of this research was to determine alternative management of glyphosate for the Chloris elata and Digitaria insularis species during the off - season of the soybean crop and to identify the morphological characteristics of the leaf surface of Chloris elata that could interfere the control with herbicides. It was studied alternatives to glyphosate for management in areas of soybean / maize production system in two experiments with weeds Chloris elata and Digitaria insularis perennial and with two mowing conditions (15 and 30 cm). The visual control of weeds, fresh and dry matter reduction were evaluated. For the morphology of the leaves of the Chloris elata species, a histological analysis was carried out using scanning electron microscopy to characterize the leaf morphology, as well as to determine the stomatal index, stomatal density and trichome density for the adaxial and abaxial surfaces of the leaves, stages 4 and 6 fully expanded leaves. Digitaria insularis was less susceptible to the management techniques used for perennial plants, requiring two sequential applications to contain the regrowth of treatments. The use of the highest dose of the herbicide haloxyfop associated with the herbicides glyphosate or ammonium glufosinate proved to be effective in the control of C. elata and D. insularis. Herbicide management potentiated herbicide action, and D. insularis weed was more susceptible to this technique than C. elata. For this management, the association of the highest dose of haloxyfop to glufosinate was effective for both grasses. The cutting heights differed only in the first evaluations. The resistant C. elata biotype showed lower stomatal density at the stage of 4 fully expanded leaves and greater density of trichomes in the stages of 6 fully expanded leaves, which may contribute to resistance to glyphosate. This species presented waxy crystal formations that surround the ostrich, in the stage of 6 fully expanded leaves, and may be related to the natural tolerance to the glyphosate of this perennial weed.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-08-22T18:44:56Z No. of bitstreams: 1 2017 - Thain? Alves dos Santos.pdf: 3011465 bytes, checksum: dfa12c411a3f74638a41876a450cb72d (MD5) / Made available in DSpace on 2018-08-22T18:44:56Z (GMT). No. of bitstreams: 1 2017 - Thain? Alves dos Santos.pdf: 3011465 bytes, checksum: dfa12c411a3f74638a41876a450cb72d (MD5) Previous issue date: 2017-02-20 / CAPES / The presence of exotic grasses in areas for reforestation is one of the main obstacles to the growth and survival of planted individuals, whether through competition for resources and / or allelopathy. Thus, the first study of this dissertation aimed to evaluate the effect of the presence of Urochloa brizantha on growth of tree species of the Atlantic Forest biome, in Serop?dica-RJ. The study included five experiments in a completely randomized design, each including one of the following species: Cedrela fissilis, Guazuma ulmifolia, Schinus terebinthifolius, Sapindus saponaria and Hymenaea courbaril. The treatments consisted of the presence or absence of U. brizantha in coexistence with the tree species. The experimental units consisted of vases containing 16 kg of soil. Monthly assessments of height, root collar diameter and seedling mortality were carried out. At 180 days post-planting the shoot and root dry masses of the tree and grass species were measured separately. The results showed strong interference of the grass on the growth of the forest species, with the shoot and root dry masses being the most affected growth variables. Among the species, C. fissilis presented high mortality when living with U. brizantha, reaching 83% of losses from the fifth month after planting. In the second study, the magnitude of competition for water, nutrients and allelopathy imposed by U. brizantha when in coexistence with Schinus terebinthifolius was evaluated. For this, a study was set up in greenhouse using as a principle the selective exclusion of competition for water, nutrients or the effect of allelopathy. The experimental units consisted of 18 kg vases with one molt of S. terebinthifolius. The experimental design consisted of a completely randomized complete factorial with three factors: (1) cohabitation or not with U. brizantha, planted in the density of 4 plants per vase; (2) supply of limiting nutrients (25% of the recommended dose) and non-limiting (200% of the recommended dose) and (3) limiting water supply (moisture maintained between wilt point at 50% field capacity) and non-limiting (humidity maintained between 60 to 80% of the field capacity). Monthly evaluations of seedling height and diameter were carried out. At 180 days, the dry masses of the shoot and root of the tree and grass species were measured. The results showed strong competition of the grass over the tree species. The presence of the grass decreased 30.5 cm the height, 1.58 mm the root collar diameter and 22.7 g and 9.5 g the shoot and root dry masses of S. terebinthifolius, respectively. The results indicated that competition for water is the main factor responsible for the reduction of S. terebinthifolius growth when living with U. brizantha, followed by competition for nutrients. The study did not allow to evaluate the existence of U. brizantha allelopathy on S. terebinthifolius, since it was not possible to concomitantly eliminate competition for water and nutrients in the proposed experimental model. The results of the two studies show the importance of the control of exotic grasses in reforestation projects with native species, for greater gains in growth and survival of introduced seedlings. / A presen?a de gram?neas ex?ticas em ?reas destinadas a reflorestamentos ? um dos principais entraves para o crescimento e sobreviv?ncia dos indiv?duos plantados, seja pela competi??o por recursos e/ou alelopatia. O primeiro estudo dessa disserta??o teve como objetivo avaliar o efeito da presen?a de Urochloa brizantha sobre o crescimento de esp?cies arb?reas do bioma Mata Atl?ntica, em Serop?dica-RJ. O estudo abrangeu cinco experimentos em delineamento inteiramente casualizado, cada um contendo uma das seguintes esp?cies: Cedrela fissilis, Guazuma ulmifolia, Schinus terebinthifolius, Sapindus saponaria e Hymenaea courbaril. Os tratamentos consistiram da presen?a ou aus?ncia de Urochloa brizantha em conviv?ncia com a muda da esp?cie florestal. As unidades experimentais constavam de vasos contendo 16 kg de solo. Foram realizadas mensalmente avalia??es de altura, di?metro do coleto e mortalidade das mudas. Aos 180 dias p?s-plantio mensurou-se a massa seca de parte a?rea e radicular da esp?cie arb?rea e da gram?nea, separadamente. Os resultados evidenciaram forte interfer?ncia do capim-braquiar?o sobre o crescimento das esp?cies florestais, sendo as massas seca de parte a?rea e radicular as vari?veis de crescimento mais afetadas. Dentre as esp?cies, C. fissilis apresentou alta mortalidade quando em conviv?ncia com U. brizantha, chegando a 83% de perdas a partir do quinto m?s ap?s o plantio. No segundo estudo foi avaliada a magnitude da competi??o por ?gua, nutrientes e alelopatia imposta por Urochloa brizantha quando em conviv?ncia com Schinus terebinthifolius. Para isso, um estudo foi montado em casa de vegeta??o utilizando como princ?pio a exclus?o seletiva da competi??o por ?gua, nutrientes ou do efeito de alelopatia. As unidades experimentais consistiram de vasos de 18 kg com uma muda de S. terebinthifolius. O delineamento experimental constituiu de um fatorial completo inteiramente casualizado com 3 fatores: (1) conviv?ncia ou n?o com U. brizantha, plantada na densidade de 4 mudas por vaso; (2) fornecimento de nutrientes limitante (25% da dose recomendada) e n?o-limitante (200% da dose recomendada) e (3) o fornecimento de ?gua limitante (umidade mantida entre ponto de murcha a 50% da capacidade de campo) e n?o-limitante (umidade mantida entre 60 a 80% da capacidade de campo). Foram realizadas mensalmente avalia??es de altura e di?metro do coleto das mudas. Aos 180 dias mensurou-se a massa seca da parte a?rea e radicular da esp?cie arb?rea e da gram?nea. Os resultados evidenciaram forte competi??o da gram?nea sobre a esp?cie arb?rea. O conv?vio com a gram?nea reduziu, em m?dia, em 30,5 cm a altura, em 1,58 mm o di?metro do coleto e em 22,7 g e 9,5 g as massas secas da parte a?rea e das ra?zes de S. terebinthifolius, respectivamente. Os resultados indicaram que a competi??o por ?gua ? o principal fator respons?vel pela redu??o do crescimento de S. terebinthifolius quando em conviv?ncia com U. brizantha, seguido pela competi??o por nutrientes. O estudo n?o possibilitou avaliar a exist?ncia de alelopatia de U. brizantha sobre S. terebinthifolius, visto que n?o foi poss?vel eliminar concomitantemente a competi??o por ?gua e nutrientes no modelo experimental proposto. Os resultados dos dois estudos executados evidenciam a import?ncia do controle de gram?neas ex?ticas em projetos de reflorestamento com esp?cies nativas, para maiores ganhos em crescimento e sobreviv?ncia das mudas introduzidas.

Millions are spent managing invasive weeds on public lands each year. Wildland invasive weed treatment bids are based primarily on acreage or hours but can be influenced by variables that increase treatment time and cost. Often neither the agency contracting the treatment nor the contractor has a clear idea of the amount of time that will be involved based on these variables. This makes it difficult to develop an accurate budget or bid for invasive weed control projects. It also limits managers in seeking funding and justifying treatment costs. A model has been developed that can predict herbicide application time due to four variables, weed canopy cover, slope, land cover, and weed visibility. Other variables were explored. The “smart” spray wand (SSW) is a new precision tool used to develop this model. The SSW is a spray wand with an integrated GPS and a flow meter for use with any type of spray system. The wand records the GPS location, herbicide flow,application time, and associated data of each treatment spray point. This information provided necessary data for the treatment time model. Weed control total treatment time (TTot) was hypothesized to include both treatment time (Tt) and rest time (Rt). The development and benefits of a wildland weed treatment time model are discussed. An accurate treatment time model could 1) establish an accurate standard for contractors and land managers, 2) assist in planning and managing limited treatment resources, and 3) justify funding requests and expenditures. The primary influence of the model is due to weed canopy cover (p=<2.2e-16, R2=0.5607), with smaller impacts by other variables. If canopy cover, slope, land cover, and weed visibility can be obtained for a weed control project, the model can be used.

This thesis reports on research that examines the early stage invasion process of Asparagus asparagoides (L.) W. Wight (bridal creeper), primarily a bird-dispersed weed, in a remnant vegetation patch. The study site is on Phillip Island, approximately 100 kilometres south east of Melbourne, Victoria. Asparagus asparagoides invasion of the remnant vegetation reserve is a relatively recent phenomenon. Landscape elements that affect bird dispersal and vegetation types that affect seedling establishment may be important factors that limit or enhance the spread of A. asparagoides. A systematic sampling strategy was adopted and data collected for a variety of landscape and vegetative variables including cover and abundance of A. asparagoides and the data were presented in a Geographic Information System (GIS). Preliminary results show that the distribution of A. asparagoides within a remnant vegetation patch is not random. It appears to have entered the reserve from two boundaries, spreading toward the centre, which to date remains sparsely colonised despite the capacity of this weed to spread rapidly over long distances by birds. A number of other outcomes are noted. Asparagus asparagoides establishment is prevented in pasture where sheep and cattle graze, and paddocks subjected to tillage practices. The exclusion of grazing in fenced off vegetation in pastures demonstrates rapid weed establishment and colonisation several hundred metres from main infestation. Field observation and visual inspection of temporal progress of invasion (using above ground weed density with tuber appearance to infer age) appear to suggest that invasion into remnant is associated with the track network. This age/density assumption is strengthened when spatial distribution is examined using a data set where low-density values for A. asparagoides are removed and compared with a data set using all A. asparagoides density values. The mapping of A. asparagoides in fenced off farm remnants suggests that velocity of spread at 191m/yr is a considerable underestimate. Subsequent analysis shows that the spatial distribution of A. asparagoides is not completely spatially random while intensity surface analysis highlights regions of low and high intensity located near track network. Mapping a density surface within GIS provided confirmatory evidence for the establishment of satellite clusters along the track network. The change in the intensity surface observed using the two data sets (lowdensity values and all density values) is also consistent with an expanding invasion occurring between two time periods. Spatial point pattern analysis using K-function statistics shows that xxii the clustering observed using GIS appears to be occurring at two scales or distances (130m- 160m and 195m-205m). The association between tracks and the invasion process observed in the initial stages of the study is examined. There is a change in density as a function of distance from a track where the density of A. asparagoides appears to reduce the further away from the track a site is and this relationship holds regardless of track width. The final stages of the study look at the development of a predictive model. Visual exploration of the data through mapping in a GIS and field observation made during data collection provide the starting point for the development of logistic models to estimate the probability of A. asparagoides presence. Finally the best overall logistic model is applied to a second independent site to determine the general applicability of the model. A number of variables that impact on the presence of A. asparagoides, particularly during the initial stages of the invasion process, are identified. While all the identified variables and the overall model are statistically significant, the model is found to correctly predict presence/absence in only 67% of cases overall. The model however could be expected to correctly predict the presence of A. asparagoides in 74% of cases and has a false positive rate of 40%. The model is applied at a second independent site and found to have an overall percent correct rate of 80% and correctly predicted A. asparagoides presence in 94% of cases. The variables identified as influential in the early stage of invasion are relatively easy to acquire by simple field survey that does not require specialist skills. When considering the model as a tool for the management of remnant vegetation communities, high false positive rates may lead to limited resources being spent on searching sites where there is no weed. However, a high false negative rate would have a larger impact on the management of the weed since the undetected infestations would form sources for new propagules. The model performs well from this point of view in that it provided low false negative rates at both sites. The value of the predictive model is its ability to provide managers with information regarding specific areas to target for weed eradication and management can use the model to assess the effectiveness of any control measures by going back to obtain new cover density data, then using the model to examine the changes over time. The model also provides a starting point for the development of a generic model of A. asparagoides invasion at sites outside of Phillip Island and could also provide the starting point for developing models that could be used for other bird-dispersed fleshy-fruited weed species.

Abstract Ecological based weed management strategies are imperative in cropping systems when herbicide use is limited or prohibited. Herbicides are not applicable in controlling wild oat (Avena fatua L.) in oat (Avena sativa L.) cropping systems, as they are closely related. Moreover, herbicide use is prohibited in organic oat cultivation, resulting in a need for developing alternative weed management strategies. Enhancing the crop competitive ability (CA) can be an essential strategy in managing weeds in such instances. Two studies were carried with the objectives to: 1) evaluate newly developed oat genotypes for their CA against wild oat; and 2) develop a competitive organic oat cropping system integrating mechanical and cultural weed control practices. In the first study, seven oat lines deliberately bred for enhanced CA and their two parental cultivars were evaluated for the CA with wild oat. The genotypes yielded similarly in the presence and in the absence of wild oat competition. The tall oat line SA050479 with greater seedling leaf size was more wild oat suppressive among all lines. Moreover, SA050479 had greater yield potential and grain quality; thus, it has the potential to be developed as a commercial wild oat suppressive cultivar. The second study used two contrasting levels of genotype, row spacing, crop density and a post-emergence harrowing and a non-harrowed control in two organic oat fields to develop an integrated weed management system. High crop density and harrowing increased the grain yield by 11% and 13% respectively. The competitive cultivar CDC Baler and high crop density (500 plants m-2) reduced weed biomass by 22% and 52% respectively. Harrowing reduced weed density by more than 50% in three site-years. The cultural and mechanical weed control practices when combined were additive in increasing grain yield and reducing weed biomass. Oat seed yields were increased by 25% when high crop density planting and harrowing were combined. Similarly, the combined effect of competitive cultivar, high crop density, and post-emergence harrowing were greater as weed biomass was reduced by 71%. The outcome of this project implies the importance of enhancing the crop CA by means of crop breeding and integrating cultural and mechanical weed control strategies. Furthermore, this study was able to identify the importance of ecological based weed management strategies in order to overcome the constraints in weed management in present oat cropping systems.

Lentil is an important pulse crop in Saskatchewan. Weed control is central to lentil production due its poor competitive ability and the few herbicide options for use on conventional varieties. Imidazolinone tolerant lentil varieties have been developed to improve herbicidal weed control and crop safety. Two studies were conducted in 2006 and 2007 in Saskatchewan with the research objective of determining the optimal weed control timing and herbicide to maximize weed control and lentil yield. The first experiment investigated the critical period of weed control (CPWC) for lentil. The CPWC was realized by investigating two components; the duration of weed interference and the duration of the weed-free period which respectively determine the beginning and end of the CPWC. The crop remained weedy or weed-free from zero to eleven lentil nodes to investigate the durations of weed interference and weed-free period. There was an inverse relationship between weed biomass and lentil yield such that lentil yield was highest when weed biomass was minimal. The CPWC was found to commence at the five node stage and continue to the ten node stage. The second experiment investigated imazethapyr / imazamox, imazamox and metribuzin + sethoxydim applied at two application times to determine the best herbicide for the CPWC. The results indicated that imazethapyr / imazamox and imazamox applied at the six node stage resulted in the overall lowest weed biomass and highest lentil yield compared to application at the two node stage. In accordance with these results and the CPWC, imazethapyr / imazamox or imazamox should be applied at or before the five to six node stage to maximize lentil yield and minimize weed biomass.

Abstract Ecological based weed management strategies are imperative in cropping systems when herbicide use is limited or prohibited. Herbicides are not applicable in controlling wild oat (Avena fatua L.) in oat (Avena sativa L.) cropping systems, as they are closely related. Moreover, herbicide use is prohibited in organic oat cultivation, resulting in a need for developing alternative weed management strategies. Enhancing the crop competitive ability (CA) can be an essential strategy in managing weeds in such instances. Two studies were carried with the objectives to: 1) evaluate newly developed oat genotypes for their CA against wild oat; and 2) develop a competitive organic oat cropping system integrating mechanical and cultural weed control practices. In the first study, seven oat lines deliberately bred for enhanced CA and their two parental cultivars were evaluated for the CA with wild oat. The genotypes yielded similarly in the presence and in the absence of wild oat competition. The tall oat line SA050479 with greater seedling leaf size was more wild oat suppressive among all lines. Moreover, SA050479 had greater yield potential and grain quality; thus, it has the potential to be developed as a commercial wild oat suppressive cultivar. The second study used two contrasting levels of genotype, row spacing, crop density and a post-emergence harrowing and a non-harrowed control in two organic oat fields to develop an integrated weed management system. High crop density and harrowing increased the grain yield by 11% and 13% respectively. The competitive cultivar CDC Baler and high crop density (500 plants m-2) reduced weed biomass by 22% and 52% respectively. Harrowing reduced weed density by more than 50% in three site-years. The cultural and mechanical weed control practices when combined were additive in increasing grain yield and reducing weed biomass. Oat seed yields were increased by 25% when high crop density planting and harrowing were combined. Similarly, the combined effect of competitive cultivar, high crop density, and post-emergence harrowing were greater as weed biomass was reduced by 71%. The outcome of this project implies the importance of enhancing the crop CA by means of crop breeding and integrating cultural and mechanical weed control strategies. Furthermore, this study was able to identify the importance of ecological based weed management strategies in order to overcome the constraints in weed management in present oat cropping systems.

Sharppod morningglory is a perennial vine commonly found infesting croplands in Texas and the southeastern United States. Previous research regarding morningglory competition and control primarily focused on annual Ipomoea. Interference, control, and herbicide translocation of sharppod morningglory could differ from that of other morningglories because of differences in growth and resource allocation. Therefore, field and laboratory experiments were conducted from 2001 to 2004 to: 1) determine the effects of seed-propagated and root-sprouted sharppod morningglory on cotton economic value, yield, harvest efficiency, and fiber quality; 2) evaluate sharppod morningglory control with cotton herbicides, and determine the effect of diuron rates on glyphosate absorption and translocation; and 3) assess the impact of cotton herbicide program and cotton-corn rotation on weed species composition over three years. A relatively large proportion of sharppod morningglory biomass was accumulated belowground during the first 8 wk of growth in the greenhouse. Consequently, up to 6 plants 10-m row-1 did not significantly reduce cotton lint yield. Sharppod morningglory density impacted color grade more than any other classification parameter. Through combined effects on yield and quality, cotton lint value was reduced by approximately 85% in the presence of 8 sharppod morningglory 10 m-1. Glyphosate alone did not completely control sharppod morningglory. The use of glufosinate, bromoxynil, or a combination of glyphosate plus diuron provided acceptable control. Sharppod morningglory absorbed up to 75% of glyphosate when applied alone, but most glyphosate was retained in treated leaves and did not translocate well. Diuron decreased absorption, increased leaf retention, and inhibited glyphosate translocation to roots. Rotation to corn and the use of preemergence herbicides in cotton improved control of grass and broadleaf weeds during the year of treatment. In the season following the 3-yr rotation, there were no lasting effects of crop rotation on density or control of grasses and broadleaves. However, hand-hoed and herbicide treated plots resulted in weed densities 2- to 3-fold lower than the untreated. Preemergence herbicides and/or crop rotation can reduce weed density and improve weed control, but these strategies must be employed long-term to reduce density of problematic weeds through depletion of the soil seedbank.

Large and small crabgrass are problem turfgrass weeds. Due to increasing cosmetic pesticide bans, assessment of crabgrass recruitment timing and cultural management response is important. This project determined that natural populations emerged later than cool season turfgrass typically establishes. While turf vigour may affect the survival of crabgrass through competition, it does not directly impact crabgrass recruitment. Considering fertilization, chamber experiments confirmed that KNO3 increased fresh seed germination. This effect did not occur with aged seed suggesting that KNO3 affects seed dormancy and not germination per se. Experiments with a model turfgrass system showed similar results where fresh seed recruitment increased with increasing fertilizer rate. Fertilization had no significant effect on recruitment in field trials. Although fresh seed was spread in the fall, recruitment did not occur until spring when seed is considered non-dormant. This suggests that typical home owner fertilization will not have a direct impact on crabgrass recruitment.