Effect of Mechanical Pruning on Olive Yield in a High Density Olive Orchard - an Account of 14 years

Abstract

In Portugal the study of the use of mechanical pruning in olive orchards began in 1997. The trials were made in traditional olive orchards and the results obtained revealed that the use of mechanical pruning can contribute for the reduction of pruning costs without reduction in yield. In 2005 the authors started the evaluation of mechanical pruning in an irrigated olive orchard (7m x 3.5m) of Picual cultivar. The trials were organised in a randomised complete block design, with three replications. Four treatments are being compared, leading to a total of 12 plots with 30 trees per plot. The treatments under study were as follow: T1 - manual pruning, using chain saws in 2005, 2010, 2014 and 2017; T2 - mechanical pruning, topping and hedging the two sides of the canopy in 2014 and 2017 followed by a manual pruning complement to remove wood suckers inside the canopy; T3 - mechanical pruning, topping the canopy parallel to the ground in 2005, topping the canopy parallel to the ground and hedging the west side of the canopy in 2008 and 2012, topping the canopy parallel to the ground and hedging the east side of the canopy in 2010, 2014 and 2017, summer topping the canopy in July 2015 (summer pruning) and hedging the west side in winter 2016; T4 - mechanical pruning, topping the canopy parallel to the ground in 2005, topping and hedging the two sides of the canopy in 2010, 2014 and 2017 and topping the canopy in July 2015 (summer pruning). Common to all treatments were manual pruning to eliminate hanging branches in 2006 and mechanical pruning, topping the canopy parallel to the ground to eliminate 0.50m, in 2007. The average yield per tree for each treatment was evaluated. In a first period of 5 years, no significant differences were found between treatments. In the second period of 4 years, a greater frequency of mechanical pruning (T3) showed a lower yield with significant differences to treatment T2. In the third period of 5 years a greater severity in pruning interventions reduced the olive yield (2014). A manual pruning complement after mechanical pruning (T2) did not increase olive yield; however, the average yield over this period of time was similar. The olive yield has been maintained over a period of 14 years only applying mechanical pruning, without manual pruning complement inside de canopy.