No description available.

Thesis (M.D.)—Boston University

As the ecological importance of prairies is becoming more recognized, the number of prairie restoration projects is increasing worldwide. One of the major challenges in restoring any disturbed ecosystem is the successful establishment of native species at the expensive of invasive species. While some weedy species are gradually replaced as other, more desired, species become established, there are invasive species that, due to their level of dominance, may out-compete native species indefinitely. The objectives of this study were 1) to quantify the impact of Ambrosia trifida (giant ragweed) on the plant community of a newsly established prairie, 2) to assess any difference in effectiveness between management practices (cutting versus pulling) of A. trifida, and 3) to establish a baseline vegetation survey to be used in future evaluations and research of the prairie. In March of 2011, 30 plots (each 3 m2) were established within the 20 acre prairie including 10 control plots [C], 10 plots where A. trifida was selectively cut approximately 10 cm above ground level [Rc], and 10 plots where A. trifida was selectively pulled [Rp]. Treatment (cutting/pulling) was applied three times (April, June, and August) during the study, and in order to compare the effectiveness of the treatments, the number of removed A. trifida was recorded for the first two applications. Between April and June, the number of A. trifida decreased by a mean of 34.9 individuals in the cut plots, and increased by a mean of 12.4 individuals in the pulled plots suggesting (albeit, not significantly) that pulling may disturb the ground and promote the germination of more seeds from the seedbed. Final biomass data collection was conducted in mid August by removing the above ground biomass of all plants excluding A. trifida from four subplots within each of the 30 main plots, followed by drying and weighing of all biomass. A total of 172 plants from 30 species were removed for a total biomass of 1735.10 grams. In the control plots the mean biomass was 6.73g and the species diversity (H') was 0.037. In the treatment plots, the corresponding values were 83.39g, and 2.093. This twelve-fold difference in biomass suggests that the presence of A. trifida has a remarkable impact on the overall community of this newly established prairie and that the correct management of A. trifida could expedite the restoration process.

Palmer amaranth (Amaranthus palmeri) and common ragweed (Ambrosia artemisiifolia) can cause detrimental soybean yield loss. Due to widespread resistance to glyphosate and ALS-inhibiting herbicides, growers rely on protoporphyrinogen oxidase inhibiting herbicides (PPO) such as flumioxazin applied preemergence (PRE) and fomesafen postemergence (POST) to control both weeds. Experiments were conducted with the overarching goal of reducing PPO selection pressure for Palmer amaranth and common ragweed. Flumioxazin alone PRE controlled Palmer amaranth near 100%. However, sulfentrazone combined with pyroxasulfone or pendimethalin provided similar control to flumioxazin. Acetochlor and linuron controlled common ragweed <74%, yet controlled Palmer amaranth >96%. Glufosinate applied POST controlled Palmer amaranth and common ragweed 74-100%, regardless of PRE treatment. Flumioxazin PRE followed by fomesafen POST controlled common ragweed well; however, several non-PPO herbicide treatments or programs with only 1 PPO-inhibiting herbicide provided similar common ragweed control as the 2 PPO system (flumioxazin followed by fomesafen). Treatments consisting of a PRE and POST herbicide controlled Palmer amaranth at least 80% and common ragweed 95%. To reduce PPO selection pressure, soybean producers growing glufosinate-resistant soybean may use flumioxazin PRE followed by glufosinate POST whereas non-glufosinate-resistant soybean growers should reduce PPO herbicide use by using a non-PPO herbicide PRE. Alternatively, these producers can effectively reduce PPO selection pressure by implementing residual combinations of a PPO-inhibiting herbicide + non-PPO with spectrums of weed control that overlap at either Palmer amaranth or common ragweed. / Master of Science in Life Sciences / Soybean producers planted 35.4 million hectares in the US during 2018. Palmer amaranth (Amaranthus palmeri) and common ragweed (Ambrosia artemisiifolia) are both common and problematic in soybean production. The introduction of a glyphosate-resistant soybean cultivars coupled with glyphosate allowed soybean producers to easily control these weeds along with many other broadleaf and grass weeds. However, over reliance on glyphosate selected for biotypes of common ragweed and Palmer amaranth resistant to the herbicide. In response, soybean producers have reverted to preemergence (PRE) herbicides and alternative modes of action postemergence (POST) to control these herbicide-resistant weeds. One such herbicide mode of action is inhibition of protoporphyrinogen oxidase (PPO). Flumioxazin and fomesafen are both PPO-inhibiting herbicides and have been widely used in soybean, however increasing reliance on PPOs has selected for resistant common ragweed and Palmer amaranth biotypes. This research focused on reducing risk of PPO-inhibiting herbicide resistance development (“selection pressure”) by finding alternatives to or combinations with PPOinhibiting herbicides that would effectively control both weeds and thus preserve effectiveness of a valuable herbicide group. Of PRE herbicides applied alone, flumioxazin was the only treatment to control Palmer amaranth >79% 14 DA-PRE at Painter 2017. However, combination of PRE herbicides such as sulfentrazone or metribuzin in combination with pyroxasulfone, and pendimethalin + sulfentrazone, all controlled Palmer amaranth well. While metribuzin and pendimethalin alone did not provide as much control, a POST application of glufosinate coupled with these residual herbicides adequately controlled Palmer amaranth. Soybean producers can effectively control Palmer amaranth with a non-PPO PRE herbicide followed by glufosinate postemergence (POST) or residual combinations of a PPO + non-PPO while reducing risk of herbicide resistance development. Several PRE herbicide treatments adequately controlled common ragweed. During 2017, residual herbicides that controlled common ragweed at least 90% included flumioxazin, flumioxazin + clomazone, linuron, or metribuzin, fomesafen + linuron, and linuron + clomazone. All treatments controlled common ragweed greater than 94% during 2018, except metribuzin, linuron, and clomazone, which controlled the weed 75, 86, and 90%, respectively. Fomesafen alone or in combination with metribuzin controlled common ragweed 80 to 84%. Regardless of PRE, glufosinate POST controlled common ragweed 99% 56 and 70 days after planting (DAP). In fields infested with common ragweed yet to develop PPO resistance, growers should use a non-PPO herbicide in combination with flumioxazin PRE. Additionally, tank mixtures of effective MOAs PRE followed by glufosinate rather than a PPO POST may reduce herbicide selection pressure. The final study set out to determine which was more critical to controlling herbicideresistant Palmer amaranth and common ragweed in soybean, a PPO-inhibiting herbicide applied PRE or POST. Flumioxazin applied PRE controlled both weeds almost completely. Acetochlor and linuron did not control common ragweed as well, but controlled Palmer amaranth >96%. Both metribuzin and clomazone were weaker on common ragweed and Palmer amaranth. However, all PRE herbicide treatments followed by glufosinate or fomesafen controlled Palmer amaranth and common ragweed at least 80 and 95%, respectively. To reduce PPO selection pressure, soybean producers growing glufosinate-resistant soybean may use flumioxazin PRE followed by glufosinate POST whereas non-glufosinate-resistant growers should reduce PPO herbicide use by using a non-PPO herbicide PRE. Alternatively, these producers can effectively reduce PPO selection pressure by implementing residual combinations of a PPO-inhibiting herbicide + non-PPO with spectrums of weed control that overlap at either Palmer amaranth or common ragweed. Results from these experiments suggest PPO-inhibiting herbicides are critical for common ragweed and Palmer amaranth control. Previous research has shown effective tank mixtures with various effective MOAs has reduced the risk of herbicide resistance development. Protoporphyrinogen oxidase herbicides should be used sparingly and in combination with effective non-PPO herbicides to reduce selection pressure. / Soybean producers planted 35.4 million hectares in the US during 2018. Palmer amaranth (Amaranthus palmeri) and common ragweed (Ambrosia artemisiifolia) are both common and problematic in soybean production. The introduction of a glyphosate-resistant soybean cultivars coupled with glyphosate allowed soybean producers to easily control these weeds along with many other broadleaf and grass weeds. However, over reliance on glyphosate selected for biotypes of common ragweed and Palmer amaranth resistant to the herbicide. In response, soybean producers have reverted to preemergence (PRE) herbicides and alternative modes of action postemergence (POST) to control these herbicide-resistant weeds. One such herbicide mode of action is inhibition of protoporphyrinogen oxidase (PPO). Flumioxazin and fomesafen are both PPO-inhibiting herbicides and have been widely used in soybean, however increasing reliance on PPOs has selected for resistant common ragweed and Palmer amaranth biotypes. This research focused on reducing risk of PPO-inhibiting herbicide resistance development (“selection pressure”) by finding alternatives to or combinations with PPOinhibiting herbicides that would effectively control both weeds and thus preserve effectiveness of a valuable herbicide group. Of PRE herbicides applied alone, flumioxazin was the only treatment to control Palmer amaranth >79% 14 DA-PRE at Painter 2017. However, combination of PRE herbicides such as sulfentrazone or metribuzin in combination with pyroxasulfone, and pendimethalin + sulfentrazone, all controlled Palmer amaranth well. While metribuzin and pendimethalin alone did not provide as much control, a POST application of glufosinate coupled with these residual herbicides adequately controlled Palmer amaranth. Soybean producers can effectively control Palmer amaranth with a non-PPO PRE herbicide followed by glufosinate postemergence (POST) or residual combinations of a PPO + non-PPO while reducing risk of herbicide resistance development. Several PRE herbicide treatments adequately controlled common ragweed. During 2017, residual herbicides that controlled common ragweed at least 90% included flumioxazin, flumioxazin + clomazone, linuron, or metribuzin, fomesafen + linuron, and linuron + clomazone. All treatments controlled common ragweed greater than 94% during 2018, except metribuzin, linuron, and clomazone, which controlled the weed 75, 86, and 90%, respectively. Fomesafen alone or in combination with metribuzin controlled common ragweed 80 to 84%. Regardless of PRE, glufosinate POST controlled common ragweed 99% 56 and 70 days after planting (DAP). In fields infested with common ragweed yet to develop PPO resistance, growers should use a non-PPO herbicide in combination with flumioxazin PRE. Additionally, tank mixtures of effective MOAs PRE followed by glufosinate rather than a PPO POST may reduce herbicide selection pressure. The final study set out to determine which was more critical to controlling herbicideresistant Palmer amaranth and common ragweed in soybean, a PPO-inhibiting herbicide applied PRE or POST. Flumioxazin applied PRE controlled both weeds almost completely. Acetochlor and linuron did not control common ragweed as well, but controlled Palmer amaranth >96%. Both metribuzin and clomazone were weaker on common ragweed and Palmer amaranth. However, all PRE herbicide treatments followed by glufosinate or fomesafen controlled Palmer amaranth and common ragweed at least 80 and 95%, respectively. To reduce PPO selection pressure, soybean producers growing glufosinate-resistant soybean may use flumioxazin PRE followed by glufosinate POST whereas non-glufosinate-resistant growers should reduce PPO herbicide use by using a non-PPO herbicide PRE. Alternatively, these producers can effectively reduce PPO selection pressure by implementing residual combinations of a PPO-inhibiting herbicide + non-PPO with spectrums of weed control that overlap at either Palmer amaranth or common ragweed. Results from these experiments suggest PPO-inhibiting herbicides are critical for common ragweed and Palmer amaranth control. Previous research has shown effective tank mixtures with various effective MOAs has reduced the risk of herbicide resistance development. Protoporphyrinogen oxidase herbicides should be used sparingly and in combination with effective non-PPO herbicides to reduce selection pressure.

Giant ragweed is an extremely competitive weed and poor control in soybean could lead to significant yield losses for Ontario producers. In 2008, a giant ragweed biotype near Windsor, ON was not controlled with glyphosate and further testing confirmed it as the first glyphosate-resistant (GR) weed in Canada. Giant ragweed seed was collected from 102 locations in Essex (70), Kent (21), Lambton (10) and Waterloo (1) counties to document the occurrence and distribution of GR giant ragweed in Ontario. Giant ragweed seedlings were sprayed with glyphosate at 1800 g a.e. ha-1, and evaluated 1, 7, 14 and 28 days after application (DAA). Results from the survey concluded that there are 47 additional locations in southwestern Ontario with GR giant ragweed. The majority of the sites were found in Essex county, but there was one location in both Chatham-Kent and Lambton counties. Field trials were established at six sites with GR giant ragweed during the 2010 and 2011 growing seasons. The objectives were to determine the level of giant ragweed control with increasing doses of glyphosate, and glyphosate tank mixes applied either preplant or postemergence. Control of giant ragweed increased with higher doses of glyphosate, but only at doses that are not economical for producers. The most effective glyphosate tank mixes were 2, 4-D ester, saflufenacil, linuron, and cloransulam-methyl providing up to 98, 94, 99 and 97% control 4 weeks after application (WAA), respectively. Glyphosate plus dicamba in dicamba-tolerant soybean provided up to 100% giant ragweed control, 4 WAA at the three confined field trial locations. / Monsanto Canada Inc.; Canadian Agricultural Adaptation Program; Grain Farmers of Ontario

Current predictions of pollen levels rely strictly on historical Averages, regardless of environmental factors that might affect the timing of pollen release by different plants. For this thesis, the goal was to develop a statistical model that will accurately forecast pollen levels by correlating those daily counts to atmospheric and meteorological conditions. This project used ARIMA modeling on IBM’s SPSS Statistics 24 of daily pollen count information for multiple allergenic pollens in the Sarasota County, Florida area over a 11-year period. The pollen species in question for this project are oak and cypress trees, grass, and ragweed pollens; and Alternaria and Cladosporium mold spores. The total pollen counts for weeds, grass, trees, and overall total are also included in the 11 years of data. The atmospheric variables used to predict pollen levels are high temperature, low temperature, average temperature, precipitation, humidity, wind direction, and wind speed for daily observations over the 11-year period. Results for these models showed that maximum temperature, precipitation, humidity, and wind direction were the driving predictors behind the pollen counts in Sarasota, Florida. The analysis of the pollination periods also showed that there were phenological changes according to the specific species. The models and phenological changes are specific to the Sarasota, Florida area, and would serve as a framework for studying other pollination regions.

Le projet de thèse à pour but de produire et caractériser un nouvel allergène de pollen d'ambroisie. Le projet est décliné en cinq axes: production d'une forme recombinante mature et en conformation native, caractérisation structurale, étude de la fonction enzymatique, étude de l'allergenicité et l'immunogénicité et évaluation du potentiel thérapeutique. / The goal of the thesis project is to product and caracterize a novel ragweed pollen allergen.The project have five axes: production of recombinant mature and native form,structurale caracterization, study of enzymatique function, study of allergenicity and immunogenicity and evaluation of therapeutic potential.

No description available.

<p>Amb a 1 is the major allergen found in ragweed. Our observations have suggested that Amb a 1 may bind lipopolysaccharide (LPS), which would likely contribute to the allergenicity of Amb a 1. In order to assess whether Amb a 1 can bind LPS, peptide sequences from Amb a 1 were assayed for their ability to bind to LPS using an ELISA based LPS binding assay. A 15 amino acid sequence in the β- chain of Amb a 1 demonstrated affinity for biotin labeled <em>E. coli </em>LPS. The sequence also bound to <em>P.</em> <em>aeruginosa</em> LPS, which is structurally disparate in the lipid A region, indicating that the sequence has flexibility in recognizing different lipid A moieties, or that the binding site may not include the lipid A portion of the LPS molecule. An IL-10 ELISA was also used to determine whether the LPS bound to the peptides induced an immunological response in leukocytes. Peptides containing the LPS-binding sequence were able to bind to LPS and induce IL-10 production, suggesting the interaction between Amb a 1 and LPS may have immunological consequences. We have identified a sequence within the major ragweed allergen Amb a 1 that has the potential to bind to LPS. This indicates that the allergen may provide its own adjuvant when encountered by the immune system, leading to an enhanced immunological response to an otherwise innocuous environmental protein.</p> / Master of Science (MSc)

Herbicide combinations are common in corn production in the United States to control broadleaf and grass weed species. Studies were conducted in 1995 and 1996 to: (1) investigate the interactions of 2,4-D and dicamba with halosulfuron-methyl on common lambsquarters and common ragweed control in corn, (2) determine the effect of 2,4-D on the foliar absorption, translocation, and metabolism of 14C halosulfuron-methyl in common lambsquarters, (3) examine the interactions of 2,4-D, dicamba, and ALS-inhibitor herbicides with rimsulfuron plus thifensulfuron-methyl (RT) and with sethoxydim on giant foxtail, common ragweed, and common lambsquarters control in corn. Combinations of halosulfuron-methyl with 2,4-D or dicamba were generally additive in their effects on common lambsquarters and common ragweed control, and were occasionally synergistic on common lambsquarters. Synergistic herbicide interactions in the greenhouse were observed with 2,4-D (17 g/ha ) and halosulfuron-methyl (18 g/ha) and 2,4-D (70 g/ha ) in combination with halosulfuron-methyl at 4.5 and 36 g/ha, respectively. Absorption and translocation of 14C-halosulfuron-methyl were not influenced by the addition of 2,4-D, with absorption increasing with time. Three unknown halosulfuron-methyl metabolites (M1, M2, and M3) with Rf values of 0.0, 0.97, and 0.94, respectively, were isolated. The addition of 2,4-D increased the level of M3 at the 18 g/ha halosulfuron-methyl rate, which may contribute to common lambsquarters phytotoxicity. Antagonism on giant foxtail control was observed with all combinations of RT and 2,4-D. Tank mixtures of RT with flumetsulam plus clopyralid plus 2,4-D, atrazine, 2,4-D, and dicamba plus atrazine controlled giant foxtail £ 78% 65 (DAT). RT mixed with flumetsulam plus clopyralid plus 2,4-D injured corn 26%, and yields were reduced 34% when compared to RT alone. Giant foxtail control from sethoxydim tank-mixed with bentazon plus atrazine with urea ammonium nitrate (UAN), or with ALS-inhibiting herbicides except halosulfuron-methyl in combination with 2,4-D was 24% lower when averaged over treatments. Yields of sethoxydim-resistant (SR) corn treated with sethoxydim mixed with combinations of sulfonylurea herbicides plus 2,4-D were low, with the exception of the combination halosulfuron-methyl with sethoxydim and 2,4-D. These studies indicate that thoroughly understanding postemergence (POST) corn herbicide tank mixtures is crucial for effective weed management. / Ph. D.