Vergara - 1976 - Physiological and morphological adaptability of ri

EPIDEMIOLOGY or SOUTHERN com LEAF BLIGHT 413
Szrbroutine DEPOS. Subroutine DEPOS calculates the probability‘ of a
released spore landing on uninfected leaf tissue based on LAI. size of the field.
and percent of infected leaf area.
Subroutme iSPORUL. Subroutine SPORUL calculates the number of spores
produced based on deiv temperature, dew period. and lesion area available for
sporulation. The area available for sporulation is then reduced in proportion
to the amount of sporulation calculated.
Sicbrozttine L41. Subroutine LAI calculates the leaf-area index (LAI) of the
cornfield based on plant age and population.
SIl/JFOIIITHZ SYZE. Subroutine SIZE calculates the size of neiv. Z-day-old lesions
based on the average temperatures of the previous 2 days.
Suki-airline GEiibll. Subroutine (‘IERM calculates the percent germination
of deposited spores based on dew temperature and dew period.
Subs-airline .\"0RilL~1L. Subroutine NORMAL calculates a random value
from a normally distributed population of mean (MU) and variance (VAR).
Through use of this subroutine, variation in the calculated responses of the
various processes to the environmental conditions is introduced.
Szibrozrrine IIDP. Subroutine VDP calculates rates of disease increase (r
sens-ii Van cler Plank, 1963) and prints daily percent of infected leaf tissue and
period r values.
Verifying the simulator
Environmental data obtained during the I972 field study were submitted to
the disease model and the results of the simulated epidemic WCTC compared
with the observed results.
Final amounts ofdiseased tissue (X) were observed in four field plots. Similar
filial X values were observed from l0 simulations of the epidemic, indicating
that the simulator closely mimics the actual disease and does so with approximately
the same variability as is observed in nature.
Acknowledgements
The author is deeply grateful to Dr. R. A. Ilvre for permission to include his
published research on spore release and the effect of relative humidity on sportilation.
The research was conducted by Dr. Hvre, Research Plant Pathologist,
Northeastern Region, Agricultural Research Service. U.S. Department of
Agriculture, and adjunct professor at the Pennsylvania State University.
The section on Modeling and Simulation represents the singular research of
Dr. Lmvry B. Massie as part of his doctoral dissertation. The author thanks Dr.
Massie for his permission to include a portion of his thesis, at my discretion.
Special thanks are due to Mrs. Gabrielle Tung for her valuable assistance in
our controlled environment research on infection, colonization, and spoiulation.