ABSTRACT
Progress Curve (AUDPC) and Yield Loss . . . . . . . . . . . . . . . . . 188 11.3 Foliar Assessments and Yield Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.3.1 Leaf Area Index (LAI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 11.3.2 Beer’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 11.3.3 Radiation Use Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
11.4 Effects of Diseases on RI and RUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 11.4.1 Radiation Intercepted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 11.4.2 Last’s Forgotten Classic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 11.4.3 Radiation Use Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 11.4.4 Diseases of Root and Stem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.5 Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 11.6 Biomass Partitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 11.7 Remote Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 11.8 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Crop loss caused by plant pathogens has been reviewed extensively in a number of review articles over the past 50 years,1, 2 beginning with Chester3 in 1950. This work established the rationale for complete and thorough assessments of plant disease and its impact on crop production. For simplicity, I will refer to the effects of plant diseases on crop production as “crop loss.” With many plant pathogens, Cook4 states, “diseases that affect the growing plant and thereby limit the ability of the plant to
yield do not cause ‘crop loss’ nor can they ‘reduce yields.’ ” Cook recommends the use of terminology such as “yield limiting factor” or “constraint to yield.” This is true for crops where pests (weed, insect, or pathogen) reduce photosynthetic processes of the plant. But, in crops where growers must allow the grain or harvestable portion of the crop to mature before harvest, pests may directly infect, infest, or contaminate the crop, resulting in crop loss. The pests downgrade the quality of the crop, which makes it less valuable for commercial sale.
