The indeterminate nature of lentil (Lens culinaris Medik), in conjunction with adverse field conditions, can lead to varying degrees of maturity among plants at harvest. This variable maturity may have a negative influence on lentil production and can delay harvest. Desiccants are currently used to improve lentil crop dry-down. However, applying desiccants too early may result in reduced crop yield and quality, and also leave unacceptable herbicide residues in lentil seeds. In addition, only four herbicides (glyphosate, diquat, saflufenacil, and glufosinate) are registered as desiccants for lentil desiccation in Canada, which limits options for growers. Therefore, the objectives of this thesis were i) to determine the importance of desiccant application timing in affecting crop yield and quality, as well as herbicide residues and ii) to determine whether additional desiccants applied alone or tank-mixed with glyphosate provide better crop desiccation. Field trials were conducted at Saskatoon and Scott, Saskatchewan, from 2012 to 2014. In the application timing trial, glyphosate or saflufenacil alone, or glyphosate+saflufenacil generally decreased seed yield, thousand seed weight, and crop dry-down, and increased herbicide residue levels at earlier application timings. For example, when applied at 60% seed moisture, saflufenacil reduced yield and thousand seed weight by 22% and 10%, respectively, and resulted in glyphosate and saflufenacil residues greater than 2.0 and 0.03 ppm, respectively. Although there were no reductions in yield and thousand seed weight when desiccants were applied at 50% or 40% seed moisture, glyphosate residue exceeded 2.0 ppm. Application of desiccants at 20 or 30% seed moisture content had no effect on yield, thousand seed weight, or herbicide residues. These results indicate that desiccant application timing is critical, and should not be made before 30% seed moisture. In a second study, glufosinate and diquat tank mixed with glyphosate were the most consistent desiccants and provided optimal crop dry-down without reducing yield and thousand seed weight, and effectively reduced glyphosate residue. The other herbicides tested (pyraflufen-ethyl and flumioxazin) were found to be poor options for growers as they had sub-optimal crop desiccation and did not affect glyphosate residue.

Orientador: Silvano Bianco / Coorientador: Robinson Antonio Pitelli / Banca: Lúcia Helena Sipaúba Tavares / Banca: Claudinei da Cruz / Banca: Silvia Patrícia Carraschi de Oliveira / Banca: Matheus Nicolino Peixoto Henares / Resumo: As macrófitas aquáticas possuem papel fundamental nos ecossistemas aquáticos participando dos processos de ciclagem de nutrientes, além de servirem como abrigo e alimento para muitas espécies de peixes e outros organismos. Dentre os principais métodos de controle de macrófitas está o controle químico com o uso de herbicidas. O objetivo deste estudo foi realizar o controle químico da macrófita Hydrilla verticillata com a aplicação isolada de diquat e hidróxido de cobre, e da mistura de diquat + 1% de hidróxido de cobre. O primeiro experimento para o controle da H. verticillata e da microalga Ankistrodesmus gracilis foi realizado em sala de bioensaio em recipientes plásticos de 1,5 litros, sendo todos os tratamentos testados eficientes no controle da macrófita e da microalga. Posteriormente, foram realizados experimentos em condições de microcosmos de concreto de 600 litros e em mesocosmos de concreto de 1200 litros, com o monitoramento de variáveis da qualidade da água (temperatura, oxigênio dissolvido, condutividade elétrica e pH), teor de clorofila a, demanda biológica de oxigênio (DBO) e demanda química de oxigênio (DQO) por um período de sessenta dias após a aplicação dos tratamentos. A mistura de diquat + 1% de hidróxido de cobre foi o tratamento mais eficaz no controle da macrófita Hydrilla verticillata para a maioria dos parâmetros analisados, havendo alteração nas variáveis de qualidade da água. Foram também realizados experimentos ecotoxicológicos para organismos não-... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The macrophytes have a fundamental role in aquatic ecosystems participating in nutrient cycling processes, as well as serving as shelter and food for many species of fish and other organisms. Among the main weeds control methods is chemical control using herbicides. The aim of this study was the chemical control of the macrophyte Hydrilla verticillata with isolated application of diquat and copper hydroxide, and the mixture of diquat + 1% copper hydroxide. The first experiment for the control of H. verticillata and microalgae Ankistrodesmus gracilis was held in bioassay room in plastic containers of 1.5 liters, with all treatments tested effective in controlling macrophyte and microalgae. Subsequently, experiments were carried out under conditions of 600 liters concrete microcosms and in 1200 liters concrete mesocosms, with the monitoring of water quality variables (temperature, dissolved oxygen, electrical conductivity and pH), content chlorophyll a, demand biological oxygen (BOD) and chemical oxygen demand (COD) for a period of sixty days after the application of treatments. The mixture diquat + 1% copper hydroxide was the most effective treatment in Hydrilla verticillata of weed control for the majority of parameters, with change in water quality variables. Ecotoxicological experiments were also carried out for non-target organisms (Hyphessobrycon eques, Pomacea canaliculata, Lemna minor and Azolla caroliniana) with diquat, oxychloride and copper hydroxide, wherein the mix... (Complete abstract click electronic access below) / Doutor

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This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.

Production of efficiently synthesizable, strongly associating crown ether-based cryptands is desired for pseudorotaxane complexation of bipyridinium guests to produce suprapolymers and supramolecularly-linked block copolymers. Cryptands based on bis(meta-phenylene)-32-crown-10 (BMP32C10) were synthesized. The functionality of phenylenemethanol-BMP32C10 cryptand III-3 (Ka = 2.0 x 104 M-1) did not negatively affect binding strength, although the strength of complexation is marginal to achieve the desired suprapolymers. The cryptand dimethylpyridyl-BMP32C10 IV-2 was synthesized in an attempt to improve over the binding ability of the pyridyl-BMP32C10 cryptand IV-1; instead, interesting host design insights were discovered as binding strengths were reduced over 1000-fold. The crystal structure of IV-2 shows acyl-aryl conjugation which limits the host's ability to accept guests. Synthesis of larger cis-di(carbomethoxybenzo)-3n-crown-n crown ethers was explored using the high concentration, template technique previously reported for cDB24C8 diester. cDB30C10 diester (V-1c) was produced in 93% yield; the desired pyridyl-cDB30C10 cryptand V-12 binds paraquat strongly (Ka = 1-2x105 M-1) and diquat stronger than any other host (Ka = 1.9x106 M-1), both in 1:1 fashions; association constants were measured by ITC. X-ray crystallography of the complexes shows the cryptand's para arm is too far away to interact with paraquat and the host has numerous bifurcated interactions with diquat, explaining the difference in binding strengths. Syntheses of the regioisomers of cDB27C9 diester was also explored; the cyclization yields (cDB27C9S, VI-2: 59% and cDB27C9L, VI-3: 44%) are lower, likely due to poor attack angles due to mismatched arm length in cyclization, than the equivalent length ethyleneoxy-armed cDB24C8 and cDB30C10. Modeling of the cryptand isomers, pyridyl-cDB27C9S and pyridyl-cDB27C9L, showed that the former should improve para arm interaction with paraquat, but should be sterically hindered for diquat and the latter should have a highly flexible, poorly preorganized interaction with either type of guest. ITC, MS, and crystallography data supported the predictions. Derivatization of the pyridyl-cDB30C10 cryptand V-12 was explored using chelidamic acid (VII-1). Schemes yielding alcohol, alkyl halide, alkyne, and TEMPO functionality were followed, but failed. Currently, functionalized cryptand derivatives have not been achieved, future directions are proposed. / Ph. D.

ABSTRACT<p> Canada is currently the world leader in red lentil exports, a crop of significant economic importance to Western Canadian producers. It is important for the maintenance and growth of foreign markets that our growers are able to provide a consistent product. In the past few years, our exported red lentils have had variable quality, largely due variable weather conditions. A study was conducted to determine the effect of various preharvest treatments on the milling quality of our current red lentil cultivars. These cultivars, listed in order of increasing seed size, were CDC Robin, CDC Imperial CL, CDC Rosetown, CDC Blaze, CDC Impact CL, CDC Rouleau, CDC Redberry and CDC Red Rider. Replicated plots of each variety were grown in the summers of 2005 and 2006 at Floral, SK and Rouleau, SK. These were chosen with the intent of maximizing environmental differential between locations, especially in terms of soil texture and moisture availability. All locations were laid out using a randomized complete block design with four replicates. Replicated plots of each cultivar were subjected to preharvest treatments of desiccation with Diquat or swathing at early, recommended and late stages of maturity. The milling quality of the harvested lentils was determined for all treatment and cultivar combinations.<p> Before preharvest treatments were applied, each plot was assigned a maturity rating based on a 1 (immature) 9 (very mature) scale. Plants exhibiting pods with a buckskin colour and texture on the bottom third of the plant were considered to be at early maturity and assigned a rating of 3. Similarly, when pods of buckskin colour and texture were found in the middle third of the plant, a maturity rating of 6 was assigned while a value of 9 would be assessed when the entire plant had all brown, rattling pods except for a small portion of buckskin pods in the top third of the canopy.<p> Based on this 1-9 scale, a total of six different harvest treatments were carried out: swathing or chemical desiccation at early, intermediate or late stages of maturity. Swathed plots were cut using a gas-powered sickle-mower, then covered with bird mesh which was staked to the ground until harvest to prevent wind damage. Desiccated plots were sprayed with Reglone (diquat) using a CO2-pressurized backpack sprayer. They were left standing until harvest. Following mechanical harvest, seed from each plot was placed in mesh bags and forced-air-dried to approximately 13% moisture, then placed in a controlled storage chamber held at 5oC.<p> Seed samples of two complete sets of replicated treatments were cleaned, then sized by passing them over round, then slotted sieves using the forty-shakes method. The two most frequent seed diameter and thickness fractions from each plot were set aside for milling. Samples were hydrated to 12.5% moisture which is the ideal moisture content for high milling quality according to research conducted by Dr. Ning Wang at the Grain Research Laboratory in Winnipeg, MB. The samples were then milled using either a Satake or a Turkish table top pulse dehuller. Following milling, samples were passed through a Carter dockage tester (Simon-Day Ltd., Winnipeg, MB) to separate whole and split seeds from broken or damaged seeds and hull material. Each sample was assessed for: 1) milling efficiency (percent split and unsplit cotyledons recovered from the total sample); 2) football recovery (percent dehulled lentils with unsplit cotyledons); and 3) dehulling efficiency (percent of cotyledons with over 98% of the seed coat removed. Dehulling efficiency values were assessed using a DuPont AcurumTM seed scanner (DuPont Canada, Toronto, ON).<p> Under favorable harvest conditions, preharvest treatments had no effect on milling efficiency, percent football recovery or dehulling efficiency. However, plots subjected to cool, wet harvest conditions produced lentil samples of highly variable milling quality. Early desiccation significantly reduced milling efficiency to below 70%, whereas early swathing resulted in milling efficiency above 85%. CDC Robin and CDC Imperial CL had the highest milling efficiencies. Similarly, cool wet harvest conditions caused percent football recovery to drop from approximately 80% to around 50%. Early swathing was the most effective for producing footballs, with smaller-seeded varieties producing the most. Cool, wet harvest caused dehulling efficiency to drop from the 97.3 99.9% range to 91.5 98.7%. Early desiccation had the most negative effect on dehulling efficiency, whereas early swathing produced the highest values. Under these conditions, smaller-seeded varieties had the lowest dehulling efficiencies.<p> The results of this study will be valuable for developing agronomic practices specific to red lentil and for improving the quality of Canadas exported product.

Phytophthora infestans (Mont) de Bary is a devastating pathogen in potato producing regions around the world. Populations of the organism in Canada shifted during the mid-1990’s as the US-1 strain (A1, metalaxyl-sensitive) was displaced by the highly aggressive, US-8 strain (A2, metalaxyl-insensitive). An increase in the incidence and severity of late blight has followed. Late blight is controlled by cultural practices aimed at eliminating disease sources and by the application of foliar fungicides. Tubers can become infected at harvest from contact with blighted vines leading to severe losses in storage. In many production areas, growers desiccate vines two to three weeks prior to harvest to reduce late blight tuber rot. However, in Manitoba, because of the loss of potential yield that results from vine killing prior to harvest in a late maturing cultivar such as Russet Burbank, growers are reluctant to adopt this practice. The objective of this study was to develop recommendations for preharvest management practices that reduce storage losses due to late blight. Field trials were conducted in 1997 and 1998 to investigate the effect of vine desiccation with diquat and/or a late season application of chlorothalonil and copper hydroxide on yield, processing quality, and disease development in storage. Desiccating vines with diquat two weeks prior to harvest reduced yield and tuber size. Compared to the untreated control, the largest reductions in marketable yield were observed for the early September harvest. By the late September harvest, however, the effect of vine killing in reducing marketable yield was less apparent. Specific gravity was lower in the vine killed treatment for all harvest dates in 1997 and in the early and mid September harvests in 1998. Vine killing did not contribute to elevated levels of reducing sugars or consistently darker fry colour at harvest or during storage. Skin-set was improved when vines were desiccated for all harvest dates in 1997 and at the early September harvest date in 1998. Vine killing reduced tuber rot in storage caused by Fusarium dry rot and Pythium leak for the early and mid September harvest dates in 1997. The incidence of late blight tuber rot was reduced in storage for the early September harvest in 1998 when vines were desiccated. The late-season application of chlorothalonil and copper hydroxide did not reduce tuber rot in storage in storage either year. Results from this study indicate that vine killing two weeks before an early to mid- September harvest is not recommended in Manitoba because of reductions in yield and specific gravity. Alternative management practices to reduce late blight tuber rot in storage should be investigated. / February 2005

ABSTRACT<p> Canada is currently the world leader in red lentil exports, a crop of significant economic importance to Western Canadian producers. It is important for the maintenance and growth of foreign markets that our growers are able to provide a consistent product. In the past few years, our exported red lentils have had variable quality, largely due variable weather conditions. A study was conducted to determine the effect of various preharvest treatments on the milling quality of our current red lentil cultivars. These cultivars, listed in order of increasing seed size, were CDC Robin, CDC Imperial CL, CDC Rosetown, CDC Blaze, CDC Impact CL, CDC Rouleau, CDC Redberry and CDC Red Rider. Replicated plots of each variety were grown in the summers of 2005 and 2006 at Floral, SK and Rouleau, SK. These were chosen with the intent of maximizing environmental differential between locations, especially in terms of soil texture and moisture availability. All locations were laid out using a randomized complete block design with four replicates. Replicated plots of each cultivar were subjected to preharvest treatments of desiccation with Diquat or swathing at early, recommended and late stages of maturity. The milling quality of the harvested lentils was determined for all treatment and cultivar combinations.<p> Before preharvest treatments were applied, each plot was assigned a maturity rating based on a 1 (immature) 9 (very mature) scale. Plants exhibiting pods with a buckskin colour and texture on the bottom third of the plant were considered to be at early maturity and assigned a rating of 3. Similarly, when pods of buckskin colour and texture were found in the middle third of the plant, a maturity rating of 6 was assigned while a value of 9 would be assessed when the entire plant had all brown, rattling pods except for a small portion of buckskin pods in the top third of the canopy.<p> Based on this 1-9 scale, a total of six different harvest treatments were carried out: swathing or chemical desiccation at early, intermediate or late stages of maturity. Swathed plots were cut using a gas-powered sickle-mower, then covered with bird mesh which was staked to the ground until harvest to prevent wind damage. Desiccated plots were sprayed with Reglone (diquat) using a CO2-pressurized backpack sprayer. They were left standing until harvest. Following mechanical harvest, seed from each plot was placed in mesh bags and forced-air-dried to approximately 13% moisture, then placed in a controlled storage chamber held at 5oC.<p> Seed samples of two complete sets of replicated treatments were cleaned, then sized by passing them over round, then slotted sieves using the forty-shakes method. The two most frequent seed diameter and thickness fractions from each plot were set aside for milling. Samples were hydrated to 12.5% moisture which is the ideal moisture content for high milling quality according to research conducted by Dr. Ning Wang at the Grain Research Laboratory in Winnipeg, MB. The samples were then milled using either a Satake or a Turkish table top pulse dehuller. Following milling, samples were passed through a Carter dockage tester (Simon-Day Ltd., Winnipeg, MB) to separate whole and split seeds from broken or damaged seeds and hull material. Each sample was assessed for: 1) milling efficiency (percent split and unsplit cotyledons recovered from the total sample); 2) football recovery (percent dehulled lentils with unsplit cotyledons); and 3) dehulling efficiency (percent of cotyledons with over 98% of the seed coat removed. Dehulling efficiency values were assessed using a DuPont AcurumTM seed scanner (DuPont Canada, Toronto, ON).<p> Under favorable harvest conditions, preharvest treatments had no effect on milling efficiency, percent football recovery or dehulling efficiency. However, plots subjected to cool, wet harvest conditions produced lentil samples of highly variable milling quality. Early desiccation significantly reduced milling efficiency to below 70%, whereas early swathing resulted in milling efficiency above 85%. CDC Robin and CDC Imperial CL had the highest milling efficiencies. Similarly, cool wet harvest conditions caused percent football recovery to drop from approximately 80% to around 50%. Early swathing was the most effective for producing footballs, with smaller-seeded varieties producing the most. Cool, wet harvest caused dehulling efficiency to drop from the 97.3 99.9% range to 91.5 98.7%. Early desiccation had the most negative effect on dehulling efficiency, whereas early swathing produced the highest values. Under these conditions, smaller-seeded varieties had the lowest dehulling efficiencies.<p> The results of this study will be valuable for developing agronomic practices specific to red lentil and for improving the quality of Canadas exported product.

Phytophthora infestans (Mont) de Bary is a devastating pathogen in potato producing regions around the world. Populations of the organism in Canada shifted during the mid-1990’s as the US-1 strain (A1, metalaxyl-sensitive) was displaced by the highly aggressive, US-8 strain (A2, metalaxyl-insensitive). An increase in the incidence and severity of late blight has followed. Late blight is controlled by cultural practices aimed at eliminating disease sources and by the application of foliar fungicides. Tubers can become infected at harvest from contact with blighted vines leading to severe losses in storage. In many production areas, growers desiccate vines two to three weeks prior to harvest to reduce late blight tuber rot. However, in Manitoba, because of the loss of potential yield that results from vine killing prior to harvest in a late maturing cultivar such as Russet Burbank, growers are reluctant to adopt this practice. The objective of this study was to develop recommendations for preharvest management practices that reduce storage losses due to late blight. Field trials were conducted in 1997 and 1998 to investigate the effect of vine desiccation with diquat and/or a late season application of chlorothalonil and copper hydroxide on yield, processing quality, and disease development in storage. Desiccating vines with diquat two weeks prior to harvest reduced yield and tuber size. Compared to the untreated control, the largest reductions in marketable yield were observed for the early September harvest. By the late September harvest, however, the effect of vine killing in reducing marketable yield was less apparent. Specific gravity was lower in the vine killed treatment for all harvest dates in 1997 and in the early and mid September harvests in 1998. Vine killing did not contribute to elevated levels of reducing sugars or consistently darker fry colour at harvest or during storage. Skin-set was improved when vines were desiccated for all harvest dates in 1997 and at the early September harvest date in 1998. Vine killing reduced tuber rot in storage caused by Fusarium dry rot and Pythium leak for the early and mid September harvest dates in 1997. The incidence of late blight tuber rot was reduced in storage for the early September harvest in 1998 when vines were desiccated. The late-season application of chlorothalonil and copper hydroxide did not reduce tuber rot in storage in storage either year. Results from this study indicate that vine killing two weeks before an early to mid- September harvest is not recommended in Manitoba because of reductions in yield and specific gravity. Alternative management practices to reduce late blight tuber rot in storage should be investigated.

Phytophthora infestans (Mont) de Bary is a devastating pathogen in potato producing regions around the world. Populations of the organism in Canada shifted during the mid-1990’s as the US-1 strain (A1, metalaxyl-sensitive) was displaced by the highly aggressive, US-8 strain (A2, metalaxyl-insensitive). An increase in the incidence and severity of late blight has followed. Late blight is controlled by cultural practices aimed at eliminating disease sources and by the application of foliar fungicides. Tubers can become infected at harvest from contact with blighted vines leading to severe losses in storage. In many production areas, growers desiccate vines two to three weeks prior to harvest to reduce late blight tuber rot. However, in Manitoba, because of the loss of potential yield that results from vine killing prior to harvest in a late maturing cultivar such as Russet Burbank, growers are reluctant to adopt this practice. The objective of this study was to develop recommendations for preharvest management practices that reduce storage losses due to late blight. Field trials were conducted in 1997 and 1998 to investigate the effect of vine desiccation with diquat and/or a late season application of chlorothalonil and copper hydroxide on yield, processing quality, and disease development in storage. Desiccating vines with diquat two weeks prior to harvest reduced yield and tuber size. Compared to the untreated control, the largest reductions in marketable yield were observed for the early September harvest. By the late September harvest, however, the effect of vine killing in reducing marketable yield was less apparent. Specific gravity was lower in the vine killed treatment for all harvest dates in 1997 and in the early and mid September harvests in 1998. Vine killing did not contribute to elevated levels of reducing sugars or consistently darker fry colour at harvest or during storage. Skin-set was improved when vines were desiccated for all harvest dates in 1997 and at the early September harvest date in 1998. Vine killing reduced tuber rot in storage caused by Fusarium dry rot and Pythium leak for the early and mid September harvest dates in 1997. The incidence of late blight tuber rot was reduced in storage for the early September harvest in 1998 when vines were desiccated. The late-season application of chlorothalonil and copper hydroxide did not reduce tuber rot in storage in storage either year. Results from this study indicate that vine killing two weeks before an early to mid- September harvest is not recommended in Manitoba because of reductions in yield and specific gravity. Alternative management practices to reduce late blight tuber rot in storage should be investigated.