Weed resistance has decreased the number of herbicides that provide effective weed control in cotton. Studies were conducted to determine weed control efficacy and crop safety in cotton with herbicides not currently labeled for use in the crop. Herbicides were applied at two different timings near Starkville and Brooksville, MS. Cotton injury following application of ametryn, bentazon, florpyrauxifen-benzyl, topramezone and tolpyralate at the 3-5 or the 8-10 node growth stage ranged from 24 to 43% and 15 to 51%, respectively, up to 56 days after application. Except for bentazon, applying non-labeled herbicides to cotton at the 3-5 or 8-10 node growth stage decreased seedcotton yield 25 to 44%. Application of bentazon had no effect on yield when applied to cotton at both growth stages and may need to be further evaluated for use in cotton.

The depletion of fossil fuel reserves and global warming are the two main factors contributing to the current demand in clean and renewable energy resources. Biofuels are renewable energy resources and have an advantage over other renewable resources due to biofuels having a zero carbon footprint and most feedstock is abundant. The use of biofuels brought about major concerns and these include food, water and land security. The use of lignocellulose as bioethanol feedstock can provide a solution to the food, water and security concerns. Biofuels such as bioethanol can be produced from lignocellulose by breaking down the structure of lignocellulose liberating fermentable sugars. Amaranth lignocellulose has a potential to be used as a feedstock for bioethanol production because amaranth plants has a high yield of biomass per hectare, require very little to no irrigation and have the ability to withstand harsh environmental conditions. The aim of this study was to investigate the viability of amaranth as a feedstock for bioethanol production by using alkaline assisted microwave pretreatment. Alkaline pretreatment of amaranth using Ca(OH)2, NaOH and KOH at various concentrations (10-50 g kg-1 of alkaline solution in water) was carried out at different energy input (6-54 kJ/g). The pretreated broth was enzymatically hydrolysed using Celluclast 1.5L, Novozyme 188 and Tween 80 at pH 4.8 and 50oC for 48 hours. The hydrolysate was further fermented to ethanol using Saccharomyces cerevisiae at a pH of 4.8 and 30oC for 48 hours. The effect of microwave pretreatment on amaranth lignocellulose was evaluated using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The monomeric sugars and ethanol were quantified using high performance liquid chromatography (HPLC). A maximum sugar yield of 0.36 g/g of biomass was obtained for pretreatment with 30 g kg-1 Ca(OH)2 solution in water, 0.24 g/g of biomass was obtained for pretreatment with 50 g kg-1 NaOH solution in water and 0.21g/g of biomass was obtained for pretreatment with 50 g kg-1 KOH solution in water at 32 kJ/g of energy input. After enzymatic hydrolysis the yields increased to 0.43 g/g, 0.63 g/g and 0.52 g g-1 of biomass for Ca(OH)2 , KOH and NaOH pretreated biomass respectively. The highest ethanol yield obtained was found to be 0.18 g/g of biomass from fermentation of KOH pretreated broth. The ethanol yield obtained from fermentation of Ca(OH)2 and NaOH pretreated broth was 0.13 g/g of biomass and 0.15 g/g of biomass respectively. The results showed that an increase in concentration of alkaline solution and an increase in energy input liberate more sugars. A decrease in biomass loading was found to increase the total sugar yield. Pretreatment with KOH was found to liberate more pentose sugars than the other alkaline solutions. The morphological changes shown by the SEM images showed that microwave irradiation is effective in breaking the structure of amaranth lignocellulose. The structural changes shown by the FTIR also validated that alkaline bases were effective in breaking the lignin, cellulose and hemicellulose linkages and liberating more sugars in the process. This work has demonstrated the enormous potential that amaranth lignocellulose has on being a feedstock for bioethanol production. / MSc (Engineering Sciences in Chemical Engineering), North-West University, Potchefstroom Campus, 2014

The depletion of fossil fuel reserves and global warming are the two main factors contributing to the current demand in clean and renewable energy resources. Biofuels are renewable energy resources and have an advantage over other renewable resources due to biofuels having a zero carbon footprint and most feedstock is abundant. The use of biofuels brought about major concerns and these include food, water and land security. The use of lignocellulose as bioethanol feedstock can provide a solution to the food, water and security concerns. Biofuels such as bioethanol can be produced from lignocellulose by breaking down the structure of lignocellulose liberating fermentable sugars. Amaranth lignocellulose has a potential to be used as a feedstock for bioethanol production because amaranth plants has a high yield of biomass per hectare, require very little to no irrigation and have the ability to withstand harsh environmental conditions. The aim of this study was to investigate the viability of amaranth as a feedstock for bioethanol production by using alkaline assisted microwave pretreatment. Alkaline pretreatment of amaranth using Ca(OH)2, NaOH and KOH at various concentrations (10-50 g kg-1 of alkaline solution in water) was carried out at different energy input (6-54 kJ/g). The pretreated broth was enzymatically hydrolysed using Celluclast 1.5L, Novozyme 188 and Tween 80 at pH 4.8 and 50oC for 48 hours. The hydrolysate was further fermented to ethanol using Saccharomyces cerevisiae at a pH of 4.8 and 30oC for 48 hours. The effect of microwave pretreatment on amaranth lignocellulose was evaluated using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The monomeric sugars and ethanol were quantified using high performance liquid chromatography (HPLC). A maximum sugar yield of 0.36 g/g of biomass was obtained for pretreatment with 30 g kg-1 Ca(OH)2 solution in water, 0.24 g/g of biomass was obtained for pretreatment with 50 g kg-1 NaOH solution in water and 0.21g/g of biomass was obtained for pretreatment with 50 g kg-1 KOH solution in water at 32 kJ/g of energy input. After enzymatic hydrolysis the yields increased to 0.43 g/g, 0.63 g/g and 0.52 g g-1 of biomass for Ca(OH)2 , KOH and NaOH pretreated biomass respectively. The highest ethanol yield obtained was found to be 0.18 g/g of biomass from fermentation of KOH pretreated broth. The ethanol yield obtained from fermentation of Ca(OH)2 and NaOH pretreated broth was 0.13 g/g of biomass and 0.15 g/g of biomass respectively. The results showed that an increase in concentration of alkaline solution and an increase in energy input liberate more sugars. A decrease in biomass loading was found to increase the total sugar yield. Pretreatment with KOH was found to liberate more pentose sugars than the other alkaline solutions. The morphological changes shown by the SEM images showed that microwave irradiation is effective in breaking the structure of amaranth lignocellulose. The structural changes shown by the FTIR also validated that alkaline bases were effective in breaking the lignin, cellulose and hemicellulose linkages and liberating more sugars in the process. This work has demonstrated the enormous potential that amaranth lignocellulose has on being a feedstock for bioethanol production. / MSc (Engineering Sciences in Chemical Engineering), North-West University, Potchefstroom Campus, 2014

Italian ryegrass is a problematic weed in Mississippi corn production due to the development and proliferation of glyphosate resistance. Studies were conducted to assess Italian ryegrass control prior to planting using herbicides. Effects of fall and spring applied burndown herbicide applications for Italian ryegrass control and subsequent corn grain yield were investigated at the R.R. Foil PSRC in Starkville, MS, at the Coastal Plain Experiment Station in Newton, MS, and the Black Belt Experiment Station in Brooksville, MS on soil textures ranging from sandy loam to silt clay loam. A fall preemergence (PRE) application of S-metolachlor + metribuzin followed by paraquat in the spring provided 99% Italian ryegrass control 28 days after paraquat application. Four spring burndown treatments provided Italian ryegrass control similar to that observed following application of the fall PRE application followed by paraquat in the spring. Applications clethodim + glufosinate + paraquat + dimethenamid-P; clethodim + glufosinate + paraquat + S-metolachlor; clethodim + paraquat + dimethenamid-P; and clethodim + oxyfluorfen + paraquat + S-metolachlor resulted in similar levels of Italian ryegrass control at 96%, 98%, 94%, and 99%, respectively. Corn yield following the fall PRE followed by spring paraquat application was 10,687 kg ha-1. Corn yield following clethodim + paraquat + dimethenamid-P as well as clethodim + oxyfluorfen + paraquat + S-metolachlor applied in the spring resulted in similar corn grain yield to that following the fall PRE followed by spring paraquat application at 9,649 kg ha-1 and 9,567 kg ha-1, respectively. Spring burndown herbicide treatments could be used to control Italian ryegrass while producing similar corn yield to the standard fall herbicide followed by paraquat application in the spring.

Master of Science / Department of Food Science / Jon Faubion / There is evolving evidence that intake of whole grains protects against development of chronic diseases. Increasing the appeal of whole grain products proves difficult as they often have poor organoleptic properties attributed to the high water holding capacity, viscosity, and insolubility of components of the bran. Amaranth is a promising grain that is naturally gluten-free and has received much attention in recent years because of its excellent nutritional profile. Studies have shown encouraging approaches to modify the molecular makeup of amaranth by enzymatic hydrolysis. This approach suggests an increase in processability and incorporation of whole grain amaranth into processed foods by ameliorating the challenges inherent in the use of whole grain flours, thereby expanding consumer acceptance and intake of whole grains. This research investigates the effects of a two-level factorial design on the enzymatic hydrolysis of whole grain amaranth with enzymes alpha-amylase, cellulase, xylanase, and protease maintaining constant pH of 6 and temperature, 50°C. The main effects show decreased viscosity and water holding capacity, and increased solubility of whole grain amaranth. The most notable findings show enzymatic treatment decreases viscosity, with alpha-amylase having the most significant impact (P < 0.0001) 21,363-59± 244 cPs. Protease was eliminated from further testing as bitterness was generated with its hydrolysate. To solubilize insoluble components, a second two-level factorial design was employed analyzing pH (4.5 and 7.5) and temperature (50°C-70°C) with the same enzyme dosage as the first design. The main effects of the second design revealed alkaline conditions significantly increase soluble fiber (P < 0.0001) 3.01-5.05% ± 0.3%. Subsequent investigation proposes a response surface design with alpha-amylase in optimizing the effects of reaction time and alkaline conditions.

Stora Enso, a big Swedish-Finnish forest industry company, wants to find a substitute for the dye that is used in their edge wick analyzes. The dye amaranth, that is used today, is a classified substance that is unhealthy and hazardous. It causes irritation to the eyes, skin and respiratory system. Edge wick is a method to determine the amount of penetrated liquid into the unprotected edges of a packaging board (the surfaces are covered with plastic). It is important to analyze liquid penetration to know that the board will sustain the liquids that it might be exposed to, for example sterilizing liquid (hydrogen peroxide), juice or wine. The dye is used as coloring agent for colorless solutions to enable visual evaluation of the penetration. In the present study several colorants were screened and evaluated in edge wick tests with the standard test liquids used at Stora Enso. Machine, pilot and handmade boards were used in the tests. Surface tension of some test liquids was also determined, as it is important to know if the dyes change the liquid properties since this may influence the penetration. The result of the tests was that a new dye was found, Allura red AC. It has a similar chemical structure to amaranth and seems to act in the same way in different type of test conditions. The recommendation is that amaranth be substituted for allura red AC, since the latter is less hazardous and is not a classified substance.

Master of Science / Department of Agronomy / Dallas E. Peterson / Auxin herbicides have been widely used for broadleaf weed control since the mid-1940’s. With new auxinic herbicide-resistant traits in corn, soybean, and cotton, use of these herbicides is likely to increase. Glyphosate-resistant Palmer amaranth (Amaranthus palmeri) and common waterhemp (Amaranthus rudis) are two primary problematic weed species that will be targeted with dicamba and 2,4-D in the new systems. No-till double-crop soybean after winter wheat harvest is a popular cropping system in central and eastern Kansas, however, management of glyphosate resistant Palmer amaranth has become a serious issue. Field experiments were established near Manhattan and Hutchinson, KS, in 2016 and 2017, to compare seventeen herbicide treatments for control of Palmer amaranth and large crabgrass (Digitaria sanguinalis) in dicamba/glyphosate resistant no-till double-crop soybean after winter wheat. Herbicide programs that included a residual preemergence (PRE) treatment followed by a postemergence (POST) treatment offered greater Palmer amaranth control 8 weeks after planting when compared to PRE-only, POST-only and burndown-only treatments. All treatments that contained glyphosate POST provided complete control of large crabgrass compared to less than 43% control with PRE-only treatments. Soybean grain yield was greater in programs that included PRE followed by POST treatments, compared to PRE-only and burndown-only treatments. A second set of field experiments were established in 2017 near Manhattan and Ottawa, KS to evaluate dicamba and 2,4-D POST efficacy on Palmer amaranth and common waterhemp. Five rates of dicamba (140, 280, 560, 1121, and 2242 g ae ha⁻¹) and 2,4-D (140, 280, 560, 1121, and 2242 g ae ha⁻¹) were used to evaluate control of the Amaranthus spp. Each experiment was conducted twice at each location. Dicamba provided better Palmer amaranth and common waterhemp control than 2,4-D across the rates evaluated. Control of Palmer amaranth was 94% and 99% with dicamba rates of 1121 and 2242 g ae ha⁻¹, respectively, but 2,4-D never provided more than 80% control at any rate. The highest rates of both dicamba and 2,4-D provided greater than 91% common waterhemp control, but control was less than 78% with all other rates of both herbicides. Palmer amaranth and common waterhemp control did not exceed 73% with the highest labelled POST rates of either dicamba or 2,4-D. Auxinic herbicide-resistant traits in corn, soybean, and cotton offer new options for controlling glyphosate-resistant Palmer amaranth and common waterhemp, however proper stewardship is vital to maintain their effectiveness.

Onarm research was conducted in 2011 and 2012 to determine the postemergence and residual control by dicamba of glyphosate-resistant (GR) Palmer amaranth (Amaranthus palmeri S. Wats.). Preemergence dicamba at 0, 0.28, 0.56, and 1.1 kg ae ha-1 and 0.07 kg ae ha-1 flumioxazin was applied at 30, 15 and 0 days prior to planting. Postemergence dicamba at 0.28, 0.56, and 1.1 kg ae ha-1 with and without 0.84 kg ae ha-1 glyphosate was applied to 5, 10 and 15 cm Palmer amaranth. In addition, a greenhouse experiment was conducted in 2012 to evaluate and confirm the optimum rate for control of Palmer amaranth with a new formulation of dicamba (BAS 18322H). In the greenhouse, dicamba at 0.14, 0.28, 0.56, 1.1, and 2.2 kg ae ha-1 was applied to 5, 10, and 15 cm Palmer amaranth.

The occurrence of herbicide resistance weeds across the southern United States has been increasing. Research is needed to develop alternative control measures, while supporting sound agronomic practices. Greenhouse and field studies were conducted to evaluate cereal cover cropping techniques along with novel herbicides to determine their value for Mississippi growers. Field studies were performed to determine which combination of cereal cover crops (cereal rye, wheat and oats) and residual herbicides (S-metolachlor + metribuzin, S-metolachlor + fomesafen, pendimethalin, flumioxazin, sulfentrazone + metribuzin and pyroxasulfone + flumioxazin) would maximize soybean yield in the presence of weeds. Cereal cover crop termination methods were evaluated and a partial budget was generated to examine the total costs of growing soybeans utilizing cereal cover crops and residual herbicides. Residual herbicide applications averaged across all cereal cover crops controlled Amaranthus spp. greater than 89% by 28 DAT. Control by the cover crops alone was 67% for of Amaranthus spp. In all cereal species tested, cutting the cover crops 10 cm above the soil and leaving the residue reduced weed numbers compared to other termination methods. However, high production and implementation costs may prevent widespread adoption of cereal cover crops and residual herbicides in Mississippi. Aminocyclopyrachlor (AMCP) is a synthetic auxin herbicide currently labeled for non-crop use, but has characteristics which may make it useful as a preplant burndown (PPB) herbicide. The application of AMCP prior to planting of corn and cotton were evaluated and carryover effects to soybean were also evaluated. Tank mix combinations of AMCP with residual herbicides (rimsulfuron, flumioxazin, pyroxasulfone, pyroxasulfone+ flumioxazin and atrazine) were also evaluated. A rate titration of AMCP and its impacts on crop species were evaluated in the greenhouse. Corn showed tolerance to AMCP except at 0.28 kg ai ha-1 applied prior to planting. Cotton was sensitive to AMCP as rate increased closer to the planting date, but response depended upon soil texture. AMCP impacts on soybean showed greater sensitivity (90% injury) then all other species evaluated. Due to potential impacts on soybean and cotton, AMCP is not a potential PPB for use in Mississippi.

Eastern black nightshade, Palmer amaranth, and common pokeweed are three hard to control weed species on the Eastern Shore regions of Virginia and Maryland. Herbicide resistance and lack of herbicide efficacy further complicate the job of controlling these weeds. Studies were conducted on each of these weeds in order to determine herbicide efficacy and potential herbicide resistance. In addition, the translocation and metabolism of 14C-glyphosate was studied in common pokeweed. This research identified a population of eastern black nightshade that was differentially sensitive to families of ALS-inhibiting herbicides, with tolerance to members of the sulfonylurea family, but controlled with herbicides of the imidazolinone family. A population of Palmer amaranth was found to be glyphosate-resistant, but herbicide programs were identified that could control this biotype in soybean and corn systems. Experiments on the fate of glyphosate in common pokeweed indicated that glyphosate does not readily translocate from treated foliage to other plant parts, which may contribute to shoot regeneration from taproots following glyphosate treatment. Taken together, this research highlights the important weed control issues, including resistant and perennial weeds in agronomic crops that have arisen in Eastern Shore agriculture. This work will help growers to better assess their particular control issues, and take appropriate steps to mitigate any problems. / Ph. D.