Simulation of Chenopodium album seedling emergence

Studies were conducted to develop a model from field and laboratory studies to predict the emergence phenology of Chenopodium album. A mechanistic mod el to predict the phenology of weed seedling emergence across locations, ye ars, and tillage systems is presented. This was accomplished by the integra tion of hydrothermal time to describe germination and thermal time to descr ibe shoot elongation. The interaction of soil moisture and temperature in t he model was accounted for by the integration of hydrothermal time in algor ithms predicting seed germination. Soil temperatures within the weed seed g ermination zone were predicted by temperature ranges at different depths in the soil. Emergence phenology of C. album seedlings was predicted with gre ater accuracy under no-till and moldboard plow systems than under a chisel plow system. We attributed this lower accuracy in the chisel plow system to increased heterogeneity in the soil matrix and vertical distribution of th e seedbank caused by the chisel plow The presence or absence of Zea mays di d not affect model performance. The use of soil temperature to calculate th ermal time was a better predictor of C. album seedling emergence than air t emperature. The ability to predict weed seedling emergence phenology is an important component of an integrated weed management strategy.