Implementation of a Blast Warning System 00

Implementation of a Rice Blast Warning System-2000
Project Leader and Principal Investigators Carla Thomas, plant pathologist, FieldWise, Inc.	The primary objective of this project is to create an early warning system to let growers and PCAs know in advance about the presence of blast. The sporadic nature of the disease necessitates a better understanding of behavior under California conditions to make management decisions about fungicide applications. Assessments of weather conditions, inoculum presence and disease risk were made by the private company FieldWise, Inc. The information was accessible through the company's website and through the Zeneca Rice Disease hotline. Eight weather stations set up in rice fields were part of a larger network operated by FieldWise that covers a large part of the Sacramento Valley and includes sites in tomato fields and vineyards. This regional network permits daily updated weather forecasts and maps depicting the previous day's weather (maximum and minimum temperature, average relative humidity and precipitation). Results of this research indicate that an intense field-scouting program throughout the season may be more effective and efficient in determining the relative abundance of rice blast inoculum in a particular area. Spore traps work well in a localized, field-scale application but provide no information on what is occurring in a neighboring field. The discovery of blast in Yuba County last year for the first time supports the notion that scouting for the disease is essential in monitoring regional inoculum sources. Collection of weather data has been essential in the continuing development of a rice blast prediction model for California. Rain May 14-15 and June 8 possibly provided conditions during the early part of the season that were favorable for the development of leaf blast where inoculum was present. As the season progressed, the plant canopy closed and higher humidity and longer leaf wetness periods prevailed. The rice blast model will allow researchers to determine the risk of disease development as the plants approach heading. This is the critical time to decide whether a fungicide application is warranted. Intense field scouting and development of disease progress curves are needed to test the validity of the rice blast model.

Implementation of a Rice
Blast Warning System-2000

Project Leader and Principal Investigators

Carla Thomas, plant pathologist, FieldWise, Inc.

The primary objective of this project is to create an early warning system to let growers and PCAs know in advance about the presence of blast. The sporadic nature of the disease necessitates a better understanding of behavior under California conditions to make management decisions about fungicide applications.

Assessments of weather conditions, inoculum presence and disease risk were made by the private company FieldWise, Inc. The information was accessible through the company's website and through the Zeneca Rice Disease hotline. Eight weather stations set up in rice fields were part of a larger network operated by FieldWise that covers a large part of the Sacramento Valley and includes sites in tomato fields and vineyards. This regional network permits daily updated weather forecasts and maps depicting the previous day's weather (maximum and minimum temperature, average relative humidity and precipitation).

Results of this research indicate that an intense field-scouting program throughout the season may be more effective and efficient in determining the relative abundance of rice blast inoculum in a particular area. Spore traps work well in a localized, field-scale application but provide no information on what is occurring in a neighboring field. The discovery of blast in Yuba County last year for the first time supports the notion that scouting for the disease is essential in monitoring regional inoculum sources.

Collection of weather data has been essential in the continuing development of a rice blast prediction model for California. Rain May 14-15 and June 8 possibly provided conditions during the early part of the season that were favorable for the development of leaf blast where inoculum was present. As the season progressed, the plant canopy closed and higher humidity and longer leaf wetness periods prevailed.

The rice blast model will allow researchers to determine the risk of disease development as the plants approach heading. This is the critical time to decide whether a fungicide application is warranted. Intense field scouting and development of disease progress curves are needed to test the validity of the rice blast model.