Effect of irrigation management and cultural practice on orchard tree bark strength

Many laboratory and field experiments were conducted to determine the potential impact of commercial shakers on the bark of almond trees during the harvest. A rapid and reliable hand device method for measuring bark strength under field conditions was developed. Various tests were conducted to select the proper dimensions of bark samples with or without reinforcement with aluminum and epoxy. Bark strength data obtained with the hand device with a digital force gauge were in good agreement with data collected with the laboratory Instron model 1122.; Field trials were conducted in an almond orchard in Bakersfield in 1998 to study the effect of irrigation management on bark strength. There were no significant differences on bark strength for three irrigation regimes. No bark damage was observed in trees harvested with commercial shakers at high pressure (13,790 kPa) for a period of 15 seconds, irrespective of the age of the tree and irrigation treatment. Field trials were repeated in 1999 to confirm the lack of effect of irrigation management on bark strength. Again, there were no significant differences in bark strength with different irrigation regimes.; Field tests for all commercial shakers were conducted for a free shake mode as well as on almond trees. Data indicated that displacement and frequency in the x and y directions for all shakers were in the range of values reported in the literature. A substantial amount of displacement in the z direction was found, approximately 27% of the displacement in the x direction. This displacement in the z direction has not been previously reported, and it might be responsible for bark damage. Also, the movement in the z direction may cause root damage and consequent infection of the root system by diseases, which could affect the productivity of the orchard.