Vol. 51—1997 - NorthEastern Weed Science Society

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The i plication of the above results is that they can be used to construct a simulation
model for pre icting weed emergence patterns under changing (field) temperature (9, 15).
The advantag of this approach includes: I) It uses the rate-summation instead of thermal
summation an therefore, provides a sound foundation for predicting emergence under
changing tern eratures; 2) It includes a stochastic component that accounts for the
emergence pa tern. The technical details are provided by Wagner et al. (15). In summary,
rates from eq ation I are accumulated under changing temperatures and act as inputs to
equation II fo predicting the cumulative proportion germinated through time. Daily
maximum an minimum temperatures, which can be obtained from simple instruments or
weather stati s, combined with parameters of equations I and II, constitute the inputs ofthe
simulation. T e output includes information on the day of first emergence, peak emergence,
and last emer ence for a population. The predicted results can be used to optimize weed
control timin ,or can be used as input into larger population dynamics models.
LITERATURE CITED
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control eeds, Weed Sci. 44:496-503.
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M.Sc. esis, Univ. Conn., Storrs, CT.
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