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Optimum Crop and Best Quality
Thanks to Mechanical Apple Bloom Thinning With Darwin 200/250
Thinning is mandatory in order to reach high fruit quality and high yields. This is very important in particular with new apple cultivars with high flowering intensity and high fruit-charge. The regulation of apple fruit is one of the most important crop factors that contribute to ensure fruit quality.
At present, in the biological cultivation of apple the surplus young fruits are removed predominantly by hand. For this purpose, there are 300 working hours per hectare needed - almost as many as for the fruit harvest. Therefore, the mechanical thinning is of large interest for the ecological fruit-growing because it allows thinning nearly independently of the weather.
Also in the conventional cultivation of apple mechanical thinning with the thinner Darwin is a very effective and economical alternative to chemical thinning.
Due to the small number of active substances certified for thinning, their weather-dependent effects and partly unsettled plant-physiological effects, thinning treatments in the bloom or in the early fructification often do not supply the desired result.
Usually this measure is therefore supplemented by hand thinning and carried out after the June drop.
In addition, an early reduction of the fruit set is very important for yield safety, in particular with alternating cultivars.
However in many cases, by the treatment with materials of thinning effect the optimal fruit cultivar yield cannot be reached (ground, planting density, and tree age).
The intensity of the effect is strongly affected by the temperature; approx. 18 - 22°C for at least three hours.
The results are good, but often limited.
One cause is on the one hand unfavorable weather conditions for the point of employment of the substances in the bloom, on the other hand application of too low or too high concentrations and/or use of a wrong water quantity per hectare.
The physiological condition of the trees plays another role, as well as still unsettled physiological reactions by which it comes altogether to an only limited effectiveness.
The idea of mechanical thinning out arose 1990 from the desire for a thinning method, which is labour-saving, chemistry-free and as weather independent as possible.
In the course of several years of work and experience, Hermann Gessler, fruit grower from the Bodensee area (Lake of Constance), developed a patented system of a mechanical thinning machine, which became generally accepted and is often used.
1995, first tests were accomplished with this thinning method in Germany and Switzerland. In 1996 the machine was tested in several areas of cultivation of fruit, among which also in South Tyrol at the Research Centre for Agriculture and Forestry Laimburg.
The machine consists of a steel girder, at which a perpendicularly rotating spindle is attached. This spindle is a steel tube with tapped holes, to which the rope device (consisting of segments of 450 mm length and 18 ropes) is fastened (around the spindle).
The distance between the plastic ropes can be specified for each section of the spindle, as the rope devices are either fully or only partly equipped with ropes. Thus, one aims a differently strong thinning within certain tree parts (bottom, middle, top).
The machine is attached to the front hydraulic system of the tractor or to the coupling mouth by means of an expander, if the tractor does not possess front hydraulic system. The hydraulic adjustment of the spindle inclination allows the adaptation to the tree form or to the ground.
The spindle together with the tractor drives closely along the tree rows and cuts thereby buds, flower clusters, or individual blooms depending upon the point of assignment.
Using the control element keys, the number of revolutions of the spindle can be adjusted comfortably and infinitely to 300-450 U/min and thus to optimally adapt the driving speed from 10km/h to 18km/h. The spindle can be stopped at any time by means of a further key, in order to exclude trees with poor flower set from thinning out.
With 1-2 ha/h surface performance, the machine has got a very high level. The thinner is available with a spindle height of 2.00 m (Darwin 200) and with a spindle height of 2.50 m (Darwin 250).
Excellent fruit size and fruit quality are reached by mechanical thinning with the Darwin 200/250. The apples at the thinned out trees are uniformly ripe and have a very distinct colouring.
Convincing arguments:
• Secured thinning effect
• Excellent thinning effect
• Increase of fruit size and quality
• Cost-effective thinning
• Effect that has an impact on alternancy
• High-area performance
• Application possible irrespective of the weather conditions
• It may be used for all current cultivars
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