Schreiber´s Slim System

SSS = Slim system - Slim expense - Slim costs!

Optimisation of expenditure and costs in modern apricot cultivation

In times of an increasingly expensive workforce, it is becoming more and more important for fruit growers with intensive crops to reduce and increasingly mechanise their working hours. This is the motto under which the Slim System was developed in the facilities of the Schreiber nursery. The word Slim is a central theme in the system, because it is slim in growing, slim in expenditure and slim in costs (S-S-S).

In modern apricot orchards with spindle training, up to 90% of the working hours are required for the 3 work steps thinning, harvesting and pruning. This is why this also offers the highest savings potential. With this in mind, the Slim System was leveraged to effectively save costs by mechanisation with machines already on the market and approaches known from other cultures.

The new features of the Slim System for apricots are the machine pruning with tree pruners, the machine thinning with Tree Darwin and the mechanically supported harvesting with harvesting platforms. The system is always adapted to the existing machines.

The planting distance in the Slim System is 3.5m x 2m, with a final tree height of 3.5m. A slim tree with a maximum overall width of 1m is grown. A strong pruning is carried out directly at planting (all shoots are shortened by 50% - 60%) in order to achieve a good growth rate and sufficient growth in the first years. As support, a maximum of one bamboo stick is put next to the tree. The aim of the first few years is to close the amniotic wall as quickly as possible in order to create a high yield potential. If there is sufficient growth, it can be pruned mechanically from the 3rd foliage.

hybriden Photo 1: The Slim System with trees in the 8th year after planting.

The mechanical pruning

New varieties with high fertility (including self-fertility) can adapt particularly well here. In the case of old varieties such as the Ungarische Beste, a too early mechanical pruning could have a negative effect on the yield behaviour, as these are not sufficiently fertile on the one-year long shoots.

The best time for pruning is the stage of the white bud. This has been shown in pruning tests at the Schreiber nursery throughout the year, as the best wound healing is achieved with the white bud until full bloom. In dry autumn years, pruning can also be carried out at the beginning to middle of September.

weisse-knospe Photo 2: In the stage of the white bud until full flowering, apricots show the best wound healing.

With pruning machines, one hectare can be pruned in approx. 3 - 4 working hours. Manual trimming is also indispensable in the slim system if you want to achieve top quality. Due to the thin pericarp, however, a large part of the fruiting is very well exposed and achieves a good fruit quality with good colouring, so that it does not have to be re-pruned every year. However, manual corrective measures should be carried out every 2 - 4 years. Inside the tree wall, shoots growing transversely and inwards are cut out or onto living stumps (at least 10 cm) to ensure good exposure of all tree elements. This effort should not exceed 50 working hours/ha and year.

For manual pruning in a spindle system (4 x 2) approx. 130 working hours/ha are required. For machine pruning with manual corrective pruning (every 2nd year) you need max. 54 hours/ha and year. In this summary, a re-pruning of 100 working hours / ha every 2nd year is aliquotly distributed to each year.

Key data for all subsequent calculations:

  • Company size: 10 ha
  • Yield per ha: 12000 kg
  • Costs per human working hours: 12 €
  • Costs per hour with tractor: 52 €
  • Repair and maintenance costs according to ÖKL guidelines (2014)

berechnung-baumschnitt Table 1: Displays the initial values and calculative key figures for the mechanical pruning in the slim system (cf. spindle).

The machine pruning works particularly well with apricots because of their high number adventitious buds. These sprout after strong pruning operations and thus ensure rapid wound healing and healthy growth. Even after eight years of machine pruning, no more tree losses could be observed in the otherwise so sensitive apricot than in manually pruned plants.

Photo 3 and 4: The apricot reacts after strong pruning interventions with a fast sprouting of adventitious buds and suckers. This can also be observed in the manual extraction of strong shoots.

The slim, mechanical pruning also helps to make other tasks more efficient. In this way, the stress of the trees can be minimised by combining them with early, mechanical thinning for flowering, thus promoting tree health.

The mechanical thinning

There are already several possibilities for machine thinning (Tree Darwin, type Bonn, Electro'flor,...). When choosing the thinning method, however, you should consider whether you want to adapt your system to the machine or vice versa. The Tree Darwin device is the first choice for slim spindle systems and slim systems, but not effective enough for hollow crowns, which is why other methods are chosen.

In combination with the slim pruning of the Slim System, the Tree Darwin achieves its best possible efficiency and utilisation, as the threads penetrate closer to the middle of the tree than with a spindle or hollow crown. Thinning with Tree Darwin requires approx. 2 working hours/ha and thus minimizes manual reworking. In contrast to mechanical pruning, an annual manual correction cannot be dispensed when thinning out - except in frost or years of alternation.

If you need up to 400 hours/ha with manual thinning for self-fertile, very rich-flowering apricot varieties, these can be reduced to approx. 70 - 100 hours by the effective use of Tree Darwin.

berechnung-ausdunnen Table 2: Shows the initial values and calculative parameters for mechanical thinning in the slim system (cf. spindle).

Even in slim spindle systems and smaller companies, the Tree Darwin device can amortise in a few years!

Apricots are particularly suitable for mechanical thinning during flowering because, unlike other types of fruit, they have not yet formed leaves at this point of time.

darvin Photo 5: Even after a strong machine thinning, too many flowers remain on the tree of very fertile varieties. Manual corrections cannot be foregone.

The early thinning time during flowering reduces the stress of the tree and increases the yield compared to later thinning times. Just a few days after the first leaves have formed, it can be observed that in flowering, heavily thinned trees already have more leaf mass than variants that were not thinned out at this point of time. Every day that is thinned out earlier increases fruit quality and yield. In addition, the stress of the tree is minimized.

If a company avoids the purchase costs of a thinning machine, manual thinning during flowering can also save time. By stripping the flowers with 2 fingers, these are reduced significantly faster than small fruits can be removed later. For overhead work in plants with a tree height of up to 3.5 m, street brooms can be a solution for flower reduction. This reduces the use of sledges, platforms or ladders as an aid. This not only saves working time and acquisition costs, but also minimizes the risk of accidents.

grosser-besen Photo 6: Thinning out with a street broom to flower can be a cost-effective alternative to other aids.

The greatest risk in this mode of operation is the risk of late frost. Especially shortly after mechanical thinning, late frost could lead to enormous yield losses and the inefficiency of an apricot plant this year. Weather events can be estimated up to 10 days in advance. If no frost events are predicted from the time of full bloom until 1 week after, one can thin out in the bloom with a clear conscience.

The year 2012 brought a very late frost night on May 18th at the Poysdorf site. This year, the variants thinned out during flowering showed less frost damage than those thinned out by hand shortly before. Apricots on trees thinned out during flowering were more robust than stressed trees, which were thinned out later. This is due to the larger leaf stand and better fruit development. However, this phenomenon should still be confirmed. A residual risk always remains.

The machine-assisted harvesting

With slim pericarps, also the harvest can be better mechanised. However, table apricots will still have to be picked by hand. The harvesting performance can be increased the most by shortening hand and footpaths.

The standard in Austrian apricot cultivation is harvesting from the ground or with picking sledges or ladders. Picking baskets, which are hung around the shoulders and in front of the stomach, are usually used. This partially blocks the harvest. Heavy picking baskets or boxes cost strength and concentration. In addition, these often have to be poured into another container for storage / sale. This can cause bruises and damage, which can lead to harvest and storage losses.

Mechanical aids adapted to apricots are difficult to find on the market, as most of the apricots available are produced for pome growing. Especially for apricots and other stone fruit, a harvest trolley from Fuhrmann has been developed.

erntewagen Photo 7: Harvesting trolley of Fa. Fuhrmann

This has a very flexible harvesting platform. Extended into the row, it serves as a stepping platform during harvesting. Furthermore, it can be tilted hydraulically to the harvest trolley and form a side wall for securing the load. The bridge can also be swivelled to the ground, next to the tyres, in order to be able to load and unload 5 euro-pallets as quickly as possible using a forklift. Harvesting takes place in boxes which can be hooked into a safety bar. This creates the shortest harvesting distance, one always has both hands free to pick and one tires more slowly, because the weight of the harvested fruit does not have to be borne by one's own body.

The logistical effort during the harvest is additionally reduced, since all boxes are directly behind the platform and therefore no extra operation is required for loading or re-delivery of boxes on the field. The use of harvesting platforms has increased the average harvesting capacity from 28 kg/h for harvesting with picking sleds to 47 kg/h.

kostenaufstellung-ernte Table 3: Shows the calculated initial values for a calculation of the harvest costs.

berechnung-ernte Table 4: Shows the calculative key figures for automatically supported harvesting in the Slim System.

Further optimization possibilities

A slim pericarp with little support material can bring further optimisation possibilities. For example, the use of tunnel sprayers is possible. Especially in young plants, up to 90% of the spray liquid used can be recovered. Older plants can still recycle about 50%, and even more in spring.

tunnelspritze Photo 8: The use of tunnel sprayers can be made possible by the cultivation of a slim pericarp.

Due to the apricot's stroke, tree losses inevitably occur again and again in the course of an orchard. If an elaborate support system (with wires) has been set up, this becomes a problem when clearing individual trees. The removal of the trees costs a lot of time and money. Clearing can be done easily without support. Here an uncomplicated pruning of the tree to the trunk can take place and then an excavator can remove the roots.

bagger-1- Photo 9: Clearing with excavators can save time and money.


Due to constantly rising labour costs, it is also becoming increasingly important to mechanise fruit growing. Apricots offer very good conditions for this. After a mechanical pruning, the apricot reacts by sprouting adventitious buds, thus ensuring rapid wound healing. A slim pruning can increase the efficiency of thinning machines and harvest performance by using adapted harvesting platforms. In addition, higher yields and better tree health can be achieved through early thinning. The Slim System can save more than 17.000€ per year compared to spindle systems in a 10ha operation. In this calculation possibly higher yields and an improved tree health are not yet included!

gesamtkostenersparnis Table 5: List of labour cost savings in the slim system (3.5 x 2m) compared to spindle systems (4 x 2m). This cost saving is due to a reduction in manpower hours of 254 working hours/year and ha

gesamtkostenersparnis-statistik Table 6: Shows labor hour savings (254 working hours) due to machine optimisation of pruning, thinning and harvesting in Schreiber´s Slim System.

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