Daily Pest Degree-Day Accumulations: Background
Daily weather data for this program are collected by the
Water and Atmospheric Resources Monitoring (WARM)
Program. Pest information is provided by the
Integrated Pest Management (IPM)
Program.
The IPM staff have provided information on base temperatures and degree-day accumulation thresholds,
as they relate to development stages for specific pests. Weather data are obtained from a
19-station array
of automated weather stations in Illinois, operated by WARM, called the Illinois Climate Network or ICN
(Hollinger et al. 1994).
Pest degree-day totals are computed using the
sine wave method
of Allen (1976). One- and two-week projections are based on the past 11 years of climate data (Easterling et
al., 1990) at each ICN site. All pest degree-day accumulations have a maximum temperature of 95° F, above
which development of the organism does not progress.
Quality control of weather data is a high priority. However, degree-day data based on the most
recent information must be considered as provisional because data are provided here early each day through a
totally automated process. Sensor malfunctions at weather stations, as well as communication and power
interruptions at the sites, do occur, which may influence downloaded data. These occurrences could
result in spurious degree-day accumulations prior to quality control verification and
data edits.
References:
Allen, J. C., 1976. A modified sine wave method for calculating degree-days.
Enviromental.
Entomology 5(3), 388-396.
Easterling, W. E. , J. R. Angel, and S. A. Kirsh, 1990.
The Appropriate Use of Climatic
Information in Illinois Natural-Gas Utility Weather-Normalization Techniques. Illinois State Water
Survey Report of Investigation 112, Champaign, Illinois, 31 pp.
Hollinger, S. E., Reinke, B. C., and Peppler, R. A., 1994.
Illinois Climate Network: Site
Descriptions, Instrumentation, and Data Management, Illinois State Water Survey Circular 178, Champaign,
Illinois, 63 pp.
