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Title: A COMPUTER SIMULATION MODEL FOR HERBICIDE UPTAKE AND TRANSLO-CATION

Author
item SATCHIVI, NORBERT - UNIV OF ILLINOIS
item WAX, LOYD
item STOLLER, EDWARD
item BRISKIN, DONALD - UNIV OF ILLINOIS

Submitted to: North Central Weed Science Society US Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/9/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A dynamic, non-linear computer simulation model was developed for whole plant uptake and translocation of foliar-applied herbicides. A validation study involving comparison of model predictions with actual data from independent studies from the literature was performed with several classes of herbicides. Simulations were conducted with hypothetical parameters describing the plant; herbicide physicochemical properties and environmental factors were based on actual data from the literature. Within the range of herbicides tested, 80% of the model predictions were close to actual absorption; the ratio of predicted/actual was between 0.8 and 1.4. The excellent correspondence between predicted and actual data was also observed with herbicide translocation. More than 60% of the model predictions were close to actual data; the ratio simulated/actual fluctuated between 0.9 and 1.5. The model provides good prediction of the relationship between the compound molecular size and its partition coefficient and cuticular penetration. Small compounds readily penetrates the cuticular. The model is a good tool to determine the relationship between the compound acid dissociation constant (pKa), octanol/water partition coefficient (logKow) and molar volume and phloem translocation. Mobility of foliar-applied herbicides depend not only on the compound pKa and logKow but also on its molecular size. The model may be also used to evaluate the effect of different surfactant molecules on herbicide uptake and translocation and is useful in the evaluation of the influence of environmental factors. This new dynamic computer simulation is a powerful tool for predicting herbicide uptake and translocation, and for the screening and design of new herbicide molecules.