Estimating the opening time of grape buds

Hlaszny, Edit – Ladányi, Márta

Keywords: opening of buds, effective accumulated temperature over the growing season, Vitis vinifera L

Modelling and forecasting the date of the opening of grape buds is an essential operation in viticulture both for the purpose of pest control and business administration. Our paper is based on data recorded for 5 white grape varieties (Chardonnay, Rajnai rizling, Hárslevelű, Pinot blanc and Szürkebarát), as well as cloned varieties, between 2000 and 2004. The vineyards are situated in the Danube wine region, in the wine subregion of Kunság, in the community of Helvécia.
The calculations were based on a mathematical model which is able to estimate the expected day of bud opening with a low margin. The model relies on the widespread method of calculating the effective accumulated temperature over the growing season and was optimised for the error of the estimated date, expressed in days. The optimum base temperature was set to 6 °C. The forecast error of the model is calculated to range from 1 to 6 days, with the mean value being 2.04 days.

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