Influence of Silicon on Managing Rice Diseases in the Everglades Agricultural Area

Situation or issue identification: Research in plant disease control generally has focused on resistant cultivars and/or fungicides. However, each of these methods of disease control has its own weaknesses. Development of new races of pathogens may break down genetic resistance. Fungicides are under intense national and international environmental scrutiny for their role as suspected or known ground water contaminants. This project evaluated an alternative approach to disease control by investigating the effect of the element, silicon, found in varying concentrations in plants, on several rice diseases, such as blast.

Rationale for research support resources: Silicon is one of the most abundant elements in the earth's crust, and most soils contain considerable quantities of this element; however, repeated cropping can reduce the levels of plant-available silicon to the point that supplemental silicon fertilization is required for maximum production. Low-silicon soils (Oxisols and Ultisols) are typically highly weathered, leached, acidic, and low in base saturation. Organic soils (Histosols) are also considered low-silicon soils. These soil conditions are commonly found in crop producing areas of the Southeastern USA, Brazil, Colombia, and other areas of Latin America, Africa, Asia and Australia. Silicon is known to reduce the severities of blast, brown spot, scald and other rice diseases. Recently, research demonstrated that silicon will enhance host plant resistance and control blast as well as brown spot to the same degree as a fungicide.

Measurable or potential impact in terms of social, economic, and/or environmental factors resulting from expenditure of research support funds: Economic: our growers know that if they have amended the soil with a plant available silicon source they do not need to apply fungicides. The cost of the fungicide plus application is about $ 16.00 per acre. If applied at two times per season on about 80% of the 22,000 acres of rice planted and amended with silicon, the cost would be about $ 563,200. Thus, this research has saved the rice growers over half million dollars annually. Social and environmental: The general public is in favor of production systems that offer alternatives to chemicals such as fungicides. Silicon fertilization represents such a system. In fact, international research centers such as International Rice Research Institute (IRRI) and International Center for Tropical Agriculture (CIAT) have been interested in this research and we have been cooperating with CIAT for the past four years on several aspects. In addition, EMBRAPA (the USDA equivalent in Brazil) is requesting our cooperation in this research.

Collaborating organizations/agencies and teaching/research/extension partnerships: USAID; USDA-OICD-NCSE; Conservation, Food and Health Foundation, Inc.; Calcium Silicates Corporation; University of Florida; CIAT; IRRI; EMBRAPA and Universidade de Uberlandia, Brazil.

For more information contact: Lawrence E. Datnoff