Shaking Functionality Evaluation of Four Different Types of Citrus Canopy-Shaker Tines

The shaking functionality of different types of shaking tines for citrus canopy shakers was evaluated. Shaking responses were simulated using ANSYS/LS-DYNA, and a tractor-mounted experimental shaking machine developed for conducting field trials. Straight nylon, bent nylon, straight PVC, and straight steel tines were used as shaking rods and, in experiments, accelerometers placed at branches and fruit to detect vibrational acceleration. Simulation results indicated that tine materials affected the vibrational response of trees and the acceleration peaks of branches and limbs exerted by a steel tine were ~2.0 times as high as exerted by a nylon tine. Both simulation and experimental results demonstrated that the tine bending stiffness had a positive effect on the generated acceleration. Tree injuries caused by a straight nylon tine were much less than by other tines. The results suggested that a shaking tine should have high stiffness, but its surface should be soft. These simulation and experiment methods can be used for improving canopy shaker applications. Keywords: Citrus harvest, Canopy shaking, Shaking functionality, Trial.

The effect of different bioregulators on lateral shoot formation in maiden apple trees

One-year-old Malus domestica Borkh. ‘Boskoop’ and ‘Mutsu’ nursery trees on M.9 rootstock were treated with foliar sprays of different BA + GA3 mixtures (450 + 450 mg dm-3 or 780 + 120 mg dm-3) or BA + GA4+7 combinations (450 + 450 or 330 + 570 mg dm-3). Both cultivars showed strong apical dominance; however, increased branching potential was observed following the use of exogenous growth regulators. All of the investigated branching agents revealed a high effectiveness, yet only after one treatment. Environmental factors played a major role in the induction of sylleptic shoot formation, especially in the case of ‘Boskoop’. In the case of ‘Boskoop’, the branching effect was correlated with several vegetative growth properties (tree height, trunk diameter), while for ‘Mutsu’, a different branching pattern was found with no correlations ascertained. No tree injuries were observed following the use of a chemical branching agent.

Analysis of the impact of injuries caused by the influence of mechanical and abiotic factors on the occurrence of harmful fungal organisms

The research described in this paper is focused on the occurrence of pathogenic microorganisms on beech trees relative to the presence of tree injuries, with the aim to ensure protection and preservation of this species in Serbia. The research was conducted in Eastern Serbia, in a hillside beech forest Fagetum moesiacae submontanum of generative origin. The testing was carried out on two sites over 51 testing plots, with a total of 829 trees and 21 species of identified fungi. On the first site it was found that the appearance of fungi primarily depends on the presence of mechanical damage on trees (as much as 73.46%), while the presence of abiotic damage has almost no bearing (only 3.21%). On the second site there was a strong correlation link between the occurrence of fungi and presence of mechanical damage - 51.88%, as well as between the fungi and abiotic damage - 47.96%. The health condition of high beech stands was found to be heavily dependent on careful and proper manipulation during harvesting, while each injury inflicted on a beech live tree during logging opens the door to infection with pathogenic microorganisms.