The influence of mechanized cutting time on the yield and quality of hops was studied for three years (2007, 2008 and 2009) in three Czech hybrid varieties Harmonie, Rubín and Agnus. The cutting term classified as 'early' was carried out at the turn of March and April. Further cutting dates were made at intervals of 7–10 days and they were classified as 'middle' and 'late' ones. Yield and contents of alpha acids were evaluated during the machine harvest. The measured data revealed no statistical relationship between term of cutting, alpha acid content and yield in any of the tested cultivars. However, during the experimental period considerable inter-annual differences were observed, especially in the yield. Average yield in the range of 2.0–2.5 t/ha in the period 2007–2008 decreased to 1.2–1.9 t/ha in 2009 due to downy mildew attack. On the basis of the obtained data it can be recommended to cut the hybrid varieties Harmonie, Rubín and Agnus in the first ten days of April, taking into account other factors such as age and the location of hop garden and current weather conditions.
Modeling of mechanized cutting of fruit trees
