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Increases in agricultural intensification over the past century have resulted in significant alterations to the rural landscape across the Midwest. Pollinators are essential to sustain natural and managed ecosystems. They are vital for food production and their declines have been linked, in part, to a rise in intensive agricultural practices. There is a recognized need among numerous stakeholders to build sustainability into the management of agroecosystems to protect both the biotic and abiotic resources of these systems. The use of cover crops is gaining interest among agricultural producers for benefits such as improving water quality and soil health. Cover cropping systems have the potential to provide floral resources to pollinators and suppress problematic driver weeds. The overall objective of this study was to quantify the effects of cover crops on plant and pollinator biodiversity within agricultural systems. This study aimed to characterize the pollinator diversity indicative of the patchwork mosaic forest-agroecosystem of Crab Orchard National Wildlife Refuge; evaluate the roles cover crop treatments play in supporting pollinator diversity and weed suppression benefits in a conventionally managed system; and provide the basis of recommendations for sustainable weed suppression tactics and for enhancing the quality of pollinator habitat within agricultural systems.

<p>Current methods of broadcast herbicide application cause a negative environmental and economic impact. Computer vision methods, specifically those related to object detection, have been reported to aid in site-specific weed management procedures to target apply herbicide on per-weed basis within a field. However, a major challenge to developing a weed detection system is the requirement for properly annotated training data to differentiate between weeds and crops under field conditions. This research involved creating an annotated database of weeds by using UAS-acquired imagery from corn and soybean research plots located in North-central Indiana. A total of 27,828 RGB; 108,398 multispectral; and 23,628 thermal images, were acquired using FLIR Duo Pro R sensor that was attached to a DJI Matrice 600 Pro UAS. An annotated database of 306 RGB images, organized into monocot and dicot weed classes, was used for network training. Two Deep Learning networks namely, DetectNet and You Only Look Once version 3 (YOLO ver3) were subjected to five training stages using four annotated image sets. The precision for weed detection ranged between 3.63-65.37% for monocot and 4.22-45.13% for dicot weed detection. This research has demonstrated a need for creating a large annotated weed database for improving precision of deep learning algorithms through better training of the network.</p>

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Made available in DSpace on 2014-06-11T19:22:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-17Bitstream added on 2014-06-13T20:48:39Z : No. of bitstreams: 1 leal_uas_me_sjrp.pdf: 567532 bytes, checksum: 52bca74b9f676be787c66a5f2d9bea27 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O propósito desta pesquisa é o estudo de dois modelos de otimização dinâmica para a aplicação seletiva de herbicida , sendo um modelo de otimização multi-objetivo , no qual maximiza o lucro e minimiza a resistência , e o utro mono-objetivo da otimização da concentração de mistura de herbicidas, no sistema anual de colheita da cultura do milho para o período de 5 e 10 anos. A densidade de sementes no solo no início do plantio e a frequência de alelos são tomados como variáveis de estado . A variável de controle é expressa na função de dose-resposta. Os modelos de otimização levam em consideração a diminuição da eficiência do herbicida ao longo do tempo , causada pela evolução da re-sistência da planta daninha . O objetivo é maximizar o lucro num período pré-determinado e minimizar a evolução da resistência. O problema de otimização dinâmica multi-objetivo foi resolvido via abordagem−restrito. O problema resultante e o problema de otimização da concentração de misturas de herbicidas foram resolvidos por programação não-linear via o método ASA_CG. Para os dois casos estudados, os resultados das simulações numéricas a presentam uma estratégia ótima da aplicação de herbicidas, para... / The purpose of this research is the study of two dynamic optimization models for the selective application/mixture of herbicide in the annual system of corn crop harvest for period of 5 and 10 years. The density o f seeds at the beginning of the planting and allele frequency are taken as state variables. The control variable is given by the dose-response function. The optimization models take into account the decreased efficiency of the herbicide overtime caused by the evolution of weed resistance. The goal is to maximize profit in a predetermined period and minimize the resistance evolution. The dynamic optimization problem of multi-objective approach was solved by the e-constraint method. The resulting problem and the problem of dynamic optimization of the concentration of the herbicide mixture were solved by non- linear programming with the conjugate gradient method combined with the method of projected gradient. Results of numerical simulations provide an optimal strategy of selective application of herbicides to control weed infestation by the Bidens subalternans. Two models studied, the first considers only... (Complete abstract click electronic access below)

This investigation represents one of the first electron microscopic studies on determining the mode of action of the chemical herbicide sethoxydim, 2-[-1-(ethoxydimino)butyl] -5-.2-(ethiothio)propyl]-3- hydroxy-2-cyclohexen-1-one. Samples were excised from the intercalary meristem of johnsongrass (Sorghum halpense) at time intervals of 1,3, 6,12,24,36,48,60, and 72 hours and examined using electron microscopy. Transmission electron micrographs revealed that cellular activity shows alterations or abnormalities as early as six hours. Membranes show deterioration at this time and chloroplasts contain densely staining starch granules. As time intervals increase, cellular degradation becomes more evident. Nuclear membranes extend outward into the cytoplasm in various types of cells. After 72 hours, the protoplasm demonstrates plasmolysis. The cell walls, plasma membranes, and plasmodesmata are also influenced by the sethoxydim treatment. Scanning electron micrographs were studied for the effects on vascular bundles and the surrounding tissue. The results were similar to those found by transmission electron miscroscopy.

Breeding herbicide-tolerant cultivars is a means of extending herbicide utilization. In 1983 and 1984, 20 soybean [Glycine max (L. Merr] cultivars were screened for their reactions to the following herbicides: metribuzin 4-amino-6-(tert)-butyl-3-(methylthio)-astriazin-5-(4H)-one]; vernolate (S-propyl dipropylthiocarbamate); and fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl) aniline]. Each herbicide was applied at the recommended rate X, 2X, and 4X in 1983. An 8X rate was added in 1984. The recommended rates (X) for the herbicides were as follows: metribuzin 0.42, vernolate 2.80, and fluchloralin 1.12 kg/ha. The cultivars were Pella, Pixie, Cumberland, Williams, Essex, Union, Semmes, Tracy, Tracy M; North American Plant Breeders 350, 68225, 420, and 330; Northrup King 8069 and 8047; and Farmers Forage Research 339, 340, 560, and 561. Plant vigor, height, and herbicide injury were the criteria used in estimating herbicide effects. Statistical differences were found among herbicides, rates, and cultivars. Also, there were significant interactions involving herbicides x rates, herbicides x cultivars, rates x cultivars, and herbicides x rates x cultivars. Although not always statistically significant, average vigor ratings decreased with increased herbicide application rate. Pronounced differences in the study results for the two years, likely reflecting rainfall patterns, were evidence of uncontrolled variability. However, a small number of the cultivars exhibited herbicide tolerance.

No-tillage production of crops has developed and become widespread since the late 1950/s. No-till is dependent upon the use of broad spectrum herbicides to kill weeds already growing at planting time. Until recently, this has almost exclusively been paraquat (1,1'-dimethy1-4,4'-bipyridinium ion). Glyphosate [N-(phosphonomethyl)glycine] is a new herbicide which has great potential for use in no -tillage production. Soybeans (Glycine max L.) were planted in the stubble after wheat (Triticum aestivum L.) was harvested. All plots received applications of the residual herbicides alachlor [2-chioro-2',6'-diethyl-N-(methoxymethyl)acetanilide] and linuron [3-(3,4-dichlorophenv1)-1-methoxy-1-methylurea]. Each plot also received either paraquat or glyphosate or was designated as a check. Glyphosate was appiied at three different volumes and paraquat at only one volume. All mixtures were applied at two spraying pressures. Applications were made to areas where straw was undisturbed after combining and to areas where the straw had been removed. Ratings taken 10 days and six weeks after herbicide application indicate that glyphosate performs as well as or better than paraquat. The ratings also indicate that glyphosate performs as well at 187 L/ha as it does at 574 L/ha. Spraying pressure and removal of straw seem to have little effect on the degree of weed control.