Agronomy Library > Annual Weeds

Fungicide Application Decision Making
Author: Kelly Turkington-AAFC, Kequan Xi-AAFRD, and Randy Kutcher-AAFC
Date Created: January 16, 2007
Last Reviewed: July 23, 2007
Introduction Currently, one of the main management tools for a number of field crop diseases is the use of resistant varieties. However, disease resistance is not always available in suitable varieties, or may have been rendered ineffective by changes in pathogen virulence resulting from continuous production of the same or similar variety. In addition, crop rotation with suitable intervals between host crops may not be feasible. When the risk of disease is high during the growing season, foliar fungicide application can benefit producers by increasing yield and kernel weight. For a number of diseases the most important negative impact is due to destruction of photosynthetic leaf area, especially in the upper canopy. Destruction of green leaf area reduces the potential amount of photosynthate available for grain development and filling, thus leading to a reduction in grain yield as well as other yield components. In contrast, sclerotinia stem rot of canola is of most concern when it attacks the main stem or branches of the canola plant, cutting off water and nutrients, resulting in premature ripening and weakening of stem and branch tissues.  Open the attached PDF file for the complete paper