Submitted to: Southeastern Pecan Growers Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 14, 2011
Publication Date: N/A
Interpretive Summary: Pecan orchard management efficiency, profitability, and yield and quality of nutmeats suffer because of insufficient understanding of how to best manage trees and orchards for nitrogen (N). Several points are identified to which orchard managers need to be aware if they are to efficiently meet tree/orchard N needs. These are recognition that not all N sources are equal, that pecan is an ammonium loving species whose vegetative and reproductive growth is influenced by the nitrate:ammonium ration, and that tree sulfur and metal micronutrient nutrition must be sufficient if N fertilizers are to be optimally utilized by trees and orchards. This information allows pecan farmers to make better choices regarding N usage, will reduce N going into the environment and improve orchard profitability.
Technical Abstract: Assessment of disease severity is required for many purposes including predicting yield loss, monitoring and forecasting epidemics, judging host resistance, and for studying fundamental biological host-pathogen processes. If assessments of disease severity are inaccurate and/or imprecise, incorrect conclusions might be drawn and incorrect actions taken. Image analysis based on digital images made using visible-wavelengths is one of several methods used to quantify disease; it offers advantages compared to visual assessment or other methods used to detect and quantitate disease intensity. Over the last thirty years, major advances have been made to improve reliability, precision and accuracy of image analysis for detecting and measuring plant disease. Although the equipment and software continues to become more sophisticated, these technologies are also becoming easier to use. The adoption of image analysis methods is expanding exponentially, and is often applied in the study of numerous host plant-disease systems. This review describes the history, technology, and application of visible-wavelength photography and image analysis, and progress towards realizing the full potential of these systems in plant disease assessment.