Experimental and modelling analysis of pesticide fate from greenhouses: The case of pyrimethanil on a tomato crop

The distribution of a pesticide on target and non-target elements of a greenhouse, and its fate after application, was studied. The experiments were performed in a round arched greenhouse with vertical side walls containing a tomato crop, located in the mainland area of Eastern Greece. The case study was designed to monitor the fate of the fungicide pyrimethanil, by measuring its concentration in the greenhouse air, on the different surfaces of greenhouse, and on the leaves of the tomato crop for several days after application. The ground within the greenhouse, which was covered by a plastic film, was the most exposed non-target element receiving about 15% of the total amount of the pesticide applied. Approximately 10% of the pesticide applied was deposited on the greenhouse walls and roof surfaces and 6% leaked to outside air through openings and ventilation. Globally, 61% of the total amount applied reached the target, i.e. the crop. In order to model the fate of pesticides in the different elements inside and outside the greenhouse, four different modelling approaches with increasing complexity and realism regarding the experimental conditions and the observed fluxes of the pesticide, were developed. Agreement between measured and estimated values of pyrimethanil concentration in the different elements improved as the complexity and realism of the model used increased. The results of the models with the greatest realism showed that after application of pyrimethanil in the greenhouse, almost no active ingredient reached outside soil and water.