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This dissertation is composed of three essays examining adoption of agricultural technologies in Ecuador and intergenerational mobility in the United States. The first essay entitled 'Does IPM Have Staying Power? Revisiting a Potato-producing Area Years After Formal Training Ended' examines (Integrated Pest Management) IPM spread and adoption several years after formal intensive IPM outreach efforts ceased in a potato-producing region in Ecuador. It describes adoption patterns and sources of IPM knowledge in 2012 and compares them with patterns that existed when outreach ceased in 2003. Results show that IPM adoption continues in the area but with a lower proportion of farmers adopting all practices and a higher proportion adopting low to moderate levels compared to 2003. Farmer-to-farmer spread has supplanted formal training and outreach mechanisms. IPM adoption significantly lowers pesticide use and saves production costs for adopters. The second essay entitled 'Can Text Messages Improve Agricultural Outreach in Ecuador?' seeks to understand how receipt of text messages complements training from a farmer field day. It measures the effect of text message receipt on adoption of (Integrated Crop Management) ICM technologies and knowledge about these technologies. In the first part of the paper, we present a theory of behavioral change and its application to adoption of agricultural technologies. In the second part, we use intention to treat (ITT) and an improved-ITT analyses to measure the impact of the intervention. The results of this essay suggest that as providers of information, text messages have some knowledge building effect leading to the adoption of IPM practices. As reminders, text messages effectively increase adoption of IPM practices, in particular recommended pesticides. The third essay entitled 'Determinants of Absolute Upward Income Mobility: The Hidden Cost of Commuting' focuses on commuting times as a determinant of upward income mobility in the United States. We provide an explanation of the channel through which the effect of commuting times on upward income mobility operates. Additionally, it evaluates empirically the effect of commuting on upward income mobility. The empirical results confirm the theoretical model predictions that commuting times affect negatively upward income mobility. / Ph. D.

Greenhouse and laboratory experiments in 2011 determined that Clonostachys rosea can effectively prevent Botrytis cinerea infection in Vaccinium angustifolium blossoms. In vitro testing demonstrated that C. rosea germination was not significantly affected by the presence of Switch®, but was by either Pristine® or Maestro®. Field experiments completed during the summer of 2010 and 2011 indicated that the dispenser designs tested had no significant effects on Bombus impatiens foraging behaviours, aside from hive-activity. There was also no difference in the quantity of C. rosea applied by each to bees, the distribution of product in the field, or for blossoms exposed to bees from each dispenser to resist infection by B. cinerea. However, B. cinerea prevalence in blossoms from both treatments was significantly different from the control, with infection reduced by 10-20%. Technical issues with dispensers currently appear to be the limiting factor for application within commercial wild blueberry production.

La protection intégrée des cultures (PIC) apparaît comme une stratégie durable de protection des plantes contre les bioagresseurs, satisfaisant les exigences à la fois économiques, écologiques et sanitaires auxquelles est confrontée l’agriculture. L’amélioration des connaissances sur les interactions entre les bioagresseurs et les pratiques agricoles est indispensable afin de concevoir des méthodes de lutte plus économes en produits phytosanitaires Le modèle IPSIM (Injury Profile SIMulator), développé dans ce travail de thèse, vise à simuler l’effet des pratiques culturales, du pédoclimat et de l’environnement de la parcelle sur les dégâts causés par les bioagresseurs sur une culture. Ce modèle est basé sur une approche hiérarchique et agrégative. Ce travail décrit la base conceptuelle de la modélisation IPSIM et son application pour construire le modèle IPSIM-Wheat, simulant les profils de dégâts sur le blé en fonction des pratiques culturales et de l’environnement biotique et abiotique. Plusieurs modèles ont été conçus pour prédire les sévérités de six maladies, un ravageur et les plantes adventices du blé. Ces modèles contribuent ainsi au développement d’IPSIM-Wheat, dont une première version est présentée pour des bioagresseurs majeurs en interaction. Ce futur modèle pourra contribuer à concevoir des systèmes de culture incluant du blé, moins soumis aux pressions biotiques et moins dépendants des pesticides. / Integrated pest management (IPM) appears as a sustainable strategy to protect plants against pest while answering the economical, ecological, and toxicological expectations that agriculture must face. The effects of cultural practices on pest dynamics have to be thoroughly analyzed in order to reduce the reliance of cropping systems on pesticides. A model, named IPSIM ((Injury Profile SIMulator), currently under development in this thesis, aims at simulating the effects of cropping practices, as well as soil, climate and field environment on the injuries caused by multiple pests of a given crop. This model is based on a hierarchical and aggregative approach. This study describes the conceptual basis of the modeling and its applications in order to develop IPSIM-Wheat, a model simulating injury profiles on wheat. Thus, several models have been designed to predict six diseases, one insect pest and weeds. This study thus contributes to the development of IPSIM-Wheat which will help design innovative sustainable wheat-based cropping system.