Training kiwifruit: T-bar and pergola

Savvas Pastopoulos, Agronomist MSc, Pastopoulos Agronomics, Neos Mylotopos, Pella, Greece

The choice between a T-bar and a pergola is made once, before the first vine goes in, and it commits the orchard for twenty years and more. The training that follows is decided in the first two seasons, when there is still no crop to show whether it went well. Both decisions start from the same place: how a kiwifruit vine grows when it is left alone.

1. What the choice of system decides

The kiwifruit vine is a woody climber, in the wild it climbs up forest trees. It forms a trunk and permanent wood like a tree, but it has not the rigidity to stand up on its own, and it has no shape of its own: the shape is given by the structure. The choice therefore is not about how the orchard looks, but about four things that are paid for every year.

• Installation cost. The pergola was more expensive than the T-bar from the beginning, and in many cases the choice was settled on that alone [2].
• Time to full production. A T-bar canopy fills in two to three years, a pergola canopy in four to six [3].
• Pruning hours. These differ by system and by pruning method far more than investment budgets assume [7][8].
• Risk management. Hail, wind, spring frost and bacterial canker are handled differently by the two systems, and the difference is structural, not a matter of spraying [2][21].

In Greece the crop reached 14,700 ha in 2024, with 342,330 tonnes and a mean yield of 23.3 t/ha, from 14.8 ha and 42 tonnes in 1980 [23]. With new plantings of the order of 1,000 ha a year and an installation cost that the Greek trade press puts above €20,000 per hectare [23][24], the training system is chosen every year on thousands of hectares, usually without anyone writing the numbers down.

Greek pomological practice recognises two dominant systems: the T-bar, with a double or single cordon, and the pergola. Recommended planting distances are 4.5–5 × 3–4 m for a T-bar with a double cordon, 4.5–5 × 2 m for a single or one-sided cordon, and 4.5–5 × 4–5 m for a pergola, with males making up at least 15% of the females [1]. Closer spacing within the row, tested in Italy in the 1990s to raise early yields from young vines [25], proved a doubtful choice: it promoted strong vegetative growth from new canes near the trunk, increased pruning costs, and the larger pruning cuts had a negative effect on fruit quality [2].

2. The architecture of the kiwifruit vine

Every training system is an attempt to fit the natural growth of the plant into a manageable geometry. In kiwifruit that natural growth has four features which govern the training [4][2].

Long shoots become pendulous under their own weight

The architecture is dominated by long upright shoots that become pendulous as they gain weight. These shoots produce leaves continuously, from both pre-formed and neo-formed nodes, until growth ceases at the end of the season. The support structure does not fight this, it uses it: it provides a horizontal plane from which the shoot will hang, with the fruit below and the leaf above.

The tip stops and a lateral takes over

While a shoot is running it has a normal apical meristem and extends from it. The difference from a tree lies in what happens once it stops. On a tree the terminal bud survives and carries the same axis on the following year, and the pruner uses it to steer the shape. In kiwifruit the tip becomes necrotic and does not start again: growth continues from a lateral bud, which first forms, passes through a period of rest and breaks later, branching that is sympodial and always proleptic. The axis of a kiwifruit vine is therefore not one shoot but a chain of successive shoots, each taking the place of the one before it [4].

When the tip stops also determines the shoot type. If it stops before the internodes extend, the shoot stays short. If it stops after, a medium shoot results. Long shoots are those that did not stop at all and carried on to the end of the growing season [4]. Greek pomological texts describe the same types by their length: canes of determinate length, 20 to 40 cm or rosettes, which come from buds beyond the tenth node, and canes of indeterminate length, a metre and more, which come from the first 9 to 10 basal buds [1].

From this comes the rule that holds for every cut: new growth breaks from the buds immediately below the point that was cut, whatever the shoot type [4]. Pruning a kiwifruit vine does not steer growth the way it does on a tree; it sets where the next link in the chain will start.

Replacement canes are born near the base of the parent cane

Here lies the practical consequence of the architecture. New replacement canes, the axes that will carry next season's crop, form near the base of the parent cane, in the transition zone between pre-formed and neo-formed nodes [4][2]. That zone lies close to the leader. The leader zone is therefore the renewal zone, and whatever shades the leader zone shades next season's wood.

Leaf area index

The leaf area index is the ratio of total leaf surface to the ground surface the leaves cover. An index of 3 means that above every square metre of ground there are three square metres of leaves, that is three layers of foliage on average.

For Hayward and Hort16A, the leaf area index that maximises the allocation of carbon to the fruit and the regeneration of reserves is put at 3 to 4 [12][10][11]. Above that, the extra foliage shades more than it photosynthesises. Shading within the canopy reduces fruit size and return bloom, measured as early as the 1980s [13] and confirmed through the relationship between canopy density and fruit quality [14].

References: 2 4 10 11 12 13 14 15

3. The T-bar

One post per position, with a horizontal cross arm at the top forming the letter T, and wires running along the row. The vine has a single trunk and two leaders spreading in opposite directions along the central wire. Fruiting canes develop along the leaders, pass over the outer wires and bend downwards, tipped about half a metre above the ground [3].

Greek pomological texts describe the system as single-trunked or double-trunked: the vine grows as a trunk and branches when it reaches the height of the wires. Those branches become the framework canes and the fruiting canes develop on them. The framework is complete in two, at most three years [1], a figure that agrees with the international literature [3].

What it gives

• A cheaper structure. Fewer wires, smaller anchors, less material per hectare than a pergola [2].
• Early entry into production. The canopy fills in two to three years [3].
• An open alley. Light reaches the ground between the rows, spray penetration is better and air moves. An open canopy with good irradiation, aeration and penetration of treatments is associated with less severe bacterial canker, while dense canopies are harder to manage and more exposed [21].
• Nets that open and close. The gaps down the centre of the alleys allow the hail net to be opened in summer and folded away in winter so that snow does not collapse it, established practice in Emilia-Romagna [2].

What it costs

• Less canopy area per vine. With short-cane pruning, the fruiting wood is concentrated near the base of the canes, exactly where growth is most vigorous. That makes it difficult to select suitable renewal wood for the following season [4][2].
• Exposure of the fruit. The canopy is thinner than a pergola canopy and fruit at the edges is more at risk from sunburn and from wind.
• Wind. Wind damage to kiwifruit is directly related to windbreak performance [20]. On a T-bar the wind enters the alley and strikes the hanging shoot from the side.

The Italian answer: long canes on a modified T-bar

In Italy the tradition was short-cane pruning on T-bars. Because that concentrates the fruiting wood at the base, a variant was introduced with long canes bent downwards, which increases the canopy area per vine and allows closer row spacing. The two systems produce equivalent yields, but the modified T-bar with long shoots produces the renewal wood types that are wanted [2].

In Piedmont, to avoid damaging frosts, tall T-bars were tested, the pergoletta alta, with structures up to 3.0 m high and fruiting canopies extending down to approximately 1 m above the ground. Yields are reputed to be 20% higher than from adjacent conventional T-bars, at the cost of pruning and harvesting from elevated platforms [9][2].

References: 1 2 3 4 9 20 21

4. The pergola

A single horizontal plane of wires, at 1.80 to 2.00 m, covering the whole planting without interruption. The wires run perpendicular to the vine rows, spaced 0.30 to 0.90 m apart [5]. The canopy has no edges: it is continuous.

The vine is taken up to the plane of the wires, at about 1.80 m, and is formed there. In Greek commercial practice a pergola is formed with two framework canes along the row, as on a T-bar, tied to the mesh. The arrangement with four canes, one in each direction, is kept for the perimeter vines, which have to fill space outwards as well [1]. The structure is built from steel and wire or from timber and wire, and the vine begins to crop in its third to fourth year [1].

What it gives

• More canopy area per vine and, in New Zealand practice, better yields of quality fruit. Many growers started with T-bars and converted them to pergolas for exactly that reason [2].
• A uniform fruit environment. Fruit hangs everywhere in the shade of the canopy, with no exposed edges.
• Protection from wind and hail. The continuous plane works equally as a net carrier and as a damper of turbulence.
• Room for a divided canopy. The techniques that broke through the conventional productivity ceiling, leader pruning, strip males, secondary canopies, alternate year cropping, all need canopy area to be built on, and the pergola is what provides it [16][15]. They are set out immediately below.

What it costs

• A more expensive structure, historically the main reason T-bars were chosen [2].
• Slow entry into production: four to six years for a full canopy [3], with extension sources reporting up to seven [5].
• Shading of the leader zone. Without discipline in pruning, the continuous canopy closes and next season's wood is formed in the dark. Every Italian and New Zealand variant, Peyracchia, leader pruning, divided canopies, solves that one problem [7][15].
• Humidity and canker. A dense, closed canopy holds moisture and hinders the penetration of treatments, with a documented link to more severe bacterial canker [21].

References: 1 2 3 5 7 15 16 21 22

5. Variants that have been tested

Every variant that has lasted does the same thing by different means: it creates a zone of open canopy so that light reaches the lower canopy and the orchard floor [2].

• The four divided-canopy techniques, leader pruning, strip males, secondary canopies and alternate year cropping. What they share is that they split the canopy in two with a lit gap between the halves instead of thickening it, and that they need the surface area of a pergola [15][16][17][22].
• Geneva double curtain. Two parallel leaders in the same row, with a gap of about 0.75 m between them, giving a horizontally divided canopy in two curtains [6][2].
• The Peyracchia system. Mixed-age pruning with partial cane replacement, which keeps a balance between old previously fruited wood and new growth. Fewer winter pruning hours [8][7].
• Stringing. Temporary strings at 40 to 60 degrees to the horizontal plane, which growing shoots latch onto and twine along. They develop in a high-light environment, which encourages flower production the following season. Expensive, because it is installed every year, but particularly useful on young vines for rapid development of leaders and canopy [18][2].
• Photo-selective hail nets. These regulate vegetative growth: blue net reduces vine vigour, while red and grey nets stimulate shoot and fruit growth [19]. Choosing the net is, in practice, part of the canopy decision.

References: 2 6 7 8 15 18 19 22

6. Planting high

Two different supports, on two different timetables

They are easily confused, because both are called a «stake» or a «post».

• The support of the vine itself. A light stake or cane beside the young plant, to which the shoot that will become the trunk is tied. The young vine has no trunk, this support is its trunk until the wood hardens and stands on its own. It is the one thing that cannot be postponed once the climb begins.
• The posts and wires of the structure. The installation that will carry the canopy and the crop. Greek pomological practice sets them at the same time as planting: driven 0.5 to 1 m into the ground so that they are firmly held, standing 2 to 2.5 m above ground, usually one post per vine [1]. In practice the structure can go up in the second year without harm: no vine reaches the wires in the first season, and the capital stays in the pocket a year longer.

Why the vine goes in high

Kiwifruit has a shallow, coarse root system with a high oxygen demand. The orchard collapse now known as kiwifruit vine decline is not attributed to a single pathogen: it arises from the interaction of soil-borne pathogens with waterlogging, standing water is what opens the door [27]. The decision to plant raised, with the crown above field level and on a strip that drains, is taken on planting day and cannot be corrected afterwards.

Males and pollination

Males must make up at least 15% of the females [1]. The ratio is not decorative: there is a linear relationship between seed number per fruit and fruit size. Even a small Hayward fruit that has just reached 70 g contains at least 525 to 740 seeds, while marketable fruit in the preferred size range needs 1,000 to 1,400 seeds [3]. New Zealand experience puts hive requirements at 8 hives per hectare, with hives moved in when 10 to 20% of the female flowers have opened [3].

References: 1 3 27

7. First season: the root, not the trunk

This is where the mistake is made that never looks like a mistake, because it looks like eagerness for a crop. The first season is not a trunk season. It is a root season.

The Greek pomological description is explicit: the vine begins to grow in spring and, as it rises, height growth is stopped at about one metre by cutting the top. From then on the vine photosynthesises and its root system develops. The vines receive all the usual care, irrigation, fertilisation, weed control [1].

Cutting the top is not a waste. The shoot tip will become necrotic in any case and the continuation will come from a lateral bud [4]; tipping simply brings forward a succession that was going to happen anyway and places it where it is wanted. By cutting at one metre, the vigour that would have gone into a thin, unstable whip is shared between foliage and root. The vine does not climb, it takes hold.

References: 1 4 21 27

8. The first winter: the decisive call

The following spring the vine is cut back low again. Vigorous lateral shoots break and one or two of them, the most vigorous, are selected to form the trunk [1]. The literature says «low» without a figure; in practice the height is about 40 cm above the ground, and the exact point is set by the anatomy of the individual vine, by where sound, well-placed buds are. A cut at ground level leaves the new vine with no reserve of wood; a cut too high keeps the problem that was there. This is the widespread Greek practice and it has a physiological basis: the shoot that breaks in the second spring is fed by a root system that has had a full growing season. Its vigour is not comparable with what the same vine had while it was in the nursery.

One shoot or two

Selecting a single shoot is the clean solution: all the vigour goes into one axis and the trunk goes up quickly. Selecting two is insurance. One of them is designated the main shoot and is taken up to the wire in the normal way. The second is stopped at about 50 cm and held there, not allowed to compete with the first: it is kept as a spare, in case the main shoot breaks at a tie, is caught by frost, is injured by machinery or turns out to be badly placed. If the main shoot does well, the spare is removed once the trunk has reached the wire and lignified, it is not kept permanently, because two trunks on one vine divide the vigour and leave a wound at the base when one of them is cut out later. The cost of the spare is small; the gain is that damage in the second season does not cost a whole season of training. This is widespread field practice and not a measured trial.

The international literature also describes the fast route: after planting, the grafted vine is headed back keeping three to five fully developed buds above the graft union, and the strongest shoot is trained up as the trunk within the same season [3]. The same sources, however, explicitly provide for the reset: if growth is inadequate, the trunk is headed back about 5 cm below the wire so that new buds break early the following season [5].

That description assumes a grafted vine, because the graft union provides the fixed reference point for the cut. In Greece most vines planted are own-rooted, so no such reference point exists: the cut is set by the vine itself, by where sound, well-placed buds are and by where mature wood ends. The rule is unchanged, only the point of measurement: a few full buds are kept on lignified wood and everything soft or thin is removed.

Video, in Greek. Taking the trunk up in the first season or the second: what is gained and what is risked in root and in wood that has not matured.

The call is made vine by vine, not for the whole block. In a new planting it is normal for a proportion of the vines to go up in the second season and the rest to be cut back again.

References: 1 3 5

9. Second season: taking the trunk up

Of the lateral shoots that broke, one is kept, or two, if a double-trunked form is intended or the second is being held as a spare [1]. All the others are removed early, while they are still soft.

• Tie to the post every 30 to 40 cm. The tie must not be tight [5].
• Remove every lateral that breaks along the trunk, uncommon while the shoot is climbing, because the tip holds dominance, and every sucker from the base, which is the rule, at each pass [5].
• Tip about 15 to 20 cm below the wire, so that the lateral buds break from which the leaders will come [3][5].

The trunk is made once and it stays. It must be upright, single and without twist: kiwifruit wood has a particular hydraulic behaviour and, in grafted plants, the graft union affects the conductance of the whole vine [26]. A trunk that was wound around the post, or that took a sharp bend, cannot be corrected; it restricts flow for the life of the planting. In high-pH areas the consequence shows earlier and more clearly: the vines develop nutrient deficiencies more readily, iron chlorosis first, because uptake in an alkaline soil is already marginal and any restriction of flow within the trunk makes it visible. The subject is covered in the article on kiwifruit nutrition.

Video, in Greek. High-pH soil of medium to heavy texture: why iron deficiency follows, and when the cost of correction makes the planting uneconomic.

In areas with frequent strong winds the support of the young shoot needs particular attention: a cane or light stake running from the ground to the wire is preferred, secured at both ends, so that the shoot does not swing. Continuous swaying breaks the soft shoot at the tie and opens wounds through which bacterial canker enters [21].

References: 1 3 5 21 26

10. Third and fourth seasons: leaders and first crop

Once the trunk reaches the wire, the systems diverge:

• T-bar. The trunk branches left and right, along the row, into two leaders. If a single-cordon form is intended, the shoot is led in one direction only [1].
• Pergola. At a height of 1.80 m, two framework canes along the row are formed, as on a T-bar, and tied to the mesh; only the perimeter vines are formed with four canes, one in each direction [1]. Lateral fruiting arms are selected every 30 to 50 cm along the leader and placed 20 to 30 cm apart alternately on either side of it [3].

Leaders are extended until they are within about one metre of the leader of the adjacent vine, and are tied to the wire with a rubber band or plastic tape, as is standard practice, they are not wound around it. The tie is left loose and renewed as the leader thickens: winding around the wire, or a tight tie, restricts sap flow later [5]. At winter pruning, the canes are headed back to wood of at least 6 mm in diameter [5]. The leaders are permanent wood and are not pruned in that way.

The first crop is kept light. The canopy has not closed and exposed fruit is sunburnt; at the same time, a crop on a vine that has not completed its framework delays training [5]. Cropping begins in earnest in the third to fourth year, once the form is complete [1].

References: 1 3 5

11. Winter pruning for production

On every framework cane or leader, heads develop, the points from which canes are produced. The objective at every head is to have at least one or two canes that will carry this season's crop and, at the same time, new vegetative canes that will carry next season's [1].

Where the crop is carried

Each cane from the previous season produces two kinds of shoot in spring. The basal buds, the first 9 to 10, give canes of indeterminate length, about a metre or more. The rest, beyond the tenth node, give canes of determinate and short length, 20 to 40 cm, or rosettes [1]. Flowers appear at the base of the cane, in the axils of the first 4 to 5 leaves, solitary or in inflorescences of three, depending on the cultivar [1].

The first buds on the cane do not count. The first four usually do not break at all, and the meristem at node five degenerates during differentiation; the zone that carries almost all the flowers in Hayward is nodes 6 to 12. So when pruning length is discussed as a number of buds, the first four are not productive, a «ten-bud» cane in fact has five or six useful ones. The evidence is set out in the article on the physiology of kiwifruit buds.

When that flowering was decided is a separate matter, and it determines which canes are worth keeping: the subject is analysed in the article on the physiology of kiwifruit buds.

Pruning length

Source of the table: [1].

How many canes are left

The literature gives a calculation that runs backwards, from the yield target. For 50 kg per vine in Hayward, with fruit of 90 to 100 g, 500 to 600 fruit are needed; if each winter cane forms 10 fruiting canes or rosettes, the vine is left with about 10 winter canes [1]. The international statement of the same thing is per square metre of canopy: 3 to 4 fruiting arms and 10 to 15 mature buds per arm, per square metre [3]. The per-square-metre form is more useful when comparing systems at different planting densities.

Timing, technique and health

• Timing. After leaf fall, completed before sap flow starts in spring. Pruning too late, once sap flow has begun, leaves cuts that bleed: the wound stays wet, is slow to close and is exposed for longer to pathogens [3].
• The cut. A cane is removed leaving a short stub, a heel, rather than cutting flush at the base, so that dieback does not reach the leader.
• Tying down. After winter pruning, all the canes that were kept are tied to the wires [1]. Tying down is essential irrespective of the support system [3].
• Renewal. Framework canes, after fruiting for a series of years, can be renewed without any problem. The whole head, and even the trunk, can be renewed if they suffer irreparable damage, after a catastrophic frost, for instance [1].
• Wounds and pathogens. Winter cuts are entry points. An open canopy with good irradiation, aeration and penetration of treatments is associated with milder bacterial canker [21]. The subject is covered in the articles on bacterial canker and on esca-like disease of kiwifruit.

References: 1 3 4 21

12. Summer pruning and tipping

In kiwifruit, summer pruning is not a supplement. In young orchards it speeds up canopy formation; in producing orchards it controls the overproduction of shoots, thins, improves ventilation and light penetration, conserves nutrients in the vine, and reduces the winter pruning workload [3]. Better air movement has one consequence that is not visible to the eye: it raises transpiration from the fruit and with it the calcium concentration in it. Calcium moves only in the transpiration stream and is not redistributed afterwards, so fruit hanging in a closed, still canopy stays low in calcium, with what that implies for firmness and storage life.

The decisions that set the season are taken in spring and early summer: how many and what size of medium and long shoots will be retained in the leader zone, to become next season's replacement canes. That is where the term leader pruning comes from [16][2].

Fruit thinning is carried out as soon as fruit shape and potential size can be identified, removing lateral fruit, misshapen fruit and poorly pollinated fruit. The guide is 1 to 2 fruit on spurs with about five leaves, 2 to 6 fruit on medium terminated shoots with 7 to 21 leaves, and 4 to 6 fruit on long non-terminated shoots [2]. The leaf-to-fruit relationship and the course of fruit growth are analysed in the article on the physiology of kiwifruit.

The two thinnings in Greek practice

The first thinning is done at bud stage, before the flowers open. Two structures are removed: the «butterflies», the double fused flowers that give a malformed and unmarketable fruit, and the laterals borne on the same peduncle as the central one. There is one exception: where the central flower is a butterfly, one lateral is left in its place, and under the right conditions it gives a normal marketable fruit.

The second thinning is done in early June, before the plant growth regulator is applied. By then the shape and the potential size of each fruit can be seen, and the malformed and the poorly pollinated are taken off. The reason it comes first is practical: the regulator enlarges whatever it finds on the vine, so every fruit that will be dropped later is wasted product and assimilate that did not go to the fruit being kept.

References: 2 3 16

13. The male vines

Male vines are pruned lightly in winter and, as soon as flowering finishes in spring, the shoots that flowered can be pruned again [3]. The flowering arms, in both females and males, should be those exposed to sufficient sunlight [3].

The critical point, however, is not the pruning but the choice: the combination of female and male cultivar must be proven to flower together under local conditions [2]. The male ratio and pollination are given in section 6.

References: 2 3

14. Mistakes that cost

15. References

The numbers in the text refer to the list below. Where only an abstract or a secondary account was used, this is stated explicitly.

• [1] Vasilakakis, M.D. General and Special Pomology (in Greek). Gartaganis Publications, Thessaloniki. Chapter «Kiwifruit», pages 837–842. Source for: orchard establishment and planting distances by system, the proportion of males, post dimensions and setting depth, the training procedure with tipping at one metre in the first season and cutting back low the following spring, the structure of the T-bar and of the pergola, the fruiting organs, the three pruning lengths, the calculation of winter canes from the yield target, the rule on the origin of the replacement cane, the renewal of framework and trunk, and the proportion of blind buds. Greek source; it takes precedence over foreign sources where they differ.
• [2] Patterson, K.J. and Thorp, T.G. (2024). Vine Management Systems. In: Richardson, A.C., Burdon, J.N. and Ferguson, A.R. (eds) Kiwifruit: Botany, Production and Uses. CAB International, pages 184–206. doi:10.1079/9781800620933.0012. Source for: the historical development of T-bar and pergola systems, the cost of and conversion between them, the zone in which replacement canes are born, the divided-canopy variants, the techniques for controlling vegetative regrowth and fruit thinning. Full text used.
• [3] Huang, H. (2016). Cultivation and Management. In: Kiwifruit: The Genus ACTINIDIA. Elsevier, pages 265–295. doi:10.1016/B978-0-12-803066-0.00007-1. Source for: the time taken to develop the canopy in each system, heading back to 3–5 buds after planting, the spacing of fruiting arms, crop load per square metre of canopy, the two faults in pruning mature vines, the timing of winter pruning, the pruning of male vines, seed number per fruit and hives per unit area. Full text used.
• [4] Seleznyova, A.N., Thorp, T.G., Barnett, A.M. and Costes, E. (2002). Quantitative analysis of shoot development and branching patterns in Actinidia. Annals of Botany 89, 471–482. doi:10.1093/aob/mcf069. Source for: sympodial, always proleptic branching, shoot-tip necrosis and the position at which replacement axes are formed.
• [5] Strik, B. and colleagues. Growing Kiwifruit, PNW 507. Pacific Northwest Extension Publication, Oregon State University, Washington State University, University of Idaho. Publication page. Source for: post, cross arm and wire dimensions, resetting the trunk when growth is inadequate, tying and lateral spacing, heading canes back to wood of at least 6 mm, and the extension of leaders. A United States extension guide, not peer-reviewed work; the dimensions apply to the Pacific Northwest.
• [6] Costa, G., Biasi, R., Giuliani, R. and Succi, F. (1992). Comparison of kiwifruit training systems. Acta Horticulturae 297, 427–434. doi:10.17660/ActaHortic.1992.297.56. Source for: the comparison of Geneva double curtain and T-bar in Hayward. The numerical results were taken from the secondary account in [2], not from the full text.
• [7] Costa, G., Quadretti, R., Galliano, A. and Vittone, F. (1997). Three-year trial of two pergola training systems for kiwifruit: traditional and Peyracchia (in Italian). Rivista di Frutticoltura e di Ortofloricoltura 61(5), 67–72. Source for: the pruning hours and yields of the two systems in the third year. Through the secondary account in [2].
• [8] Vittone, G., Franco, E., Astesano, B., Peyracchia, G. and Peyracchia, B. (1996). Pruning kiwifruit by the Peyracchia method (in Italian). Informatore Agrario 52(43), 61–66. Source for: the mixed-age method with partial cane replacement and the comparative figures for time and yield. Through the secondary account in [2].
• [9] CReSO (2010). Actinidieto a «pergoletta alta»: caratteristiche degli impianti, la fase di allevamento e indicazioni per la potatura di produzione. In: Potatura dei Fruttiferi, Supplemento a Coldiretti Informa 125, 11–14. Source for: tall T-bars up to 3.0 m, the fruiting canopy extending to about 1 m above the ground, and the reported 20% yield increase. A technical bulletin, not peer-reviewed work; through the account in [2].
• [10] Tombesi, A., Antognozzi, E. and Palliotti, A. (1994). Optimum leaf area index in T-bar trained kiwifruit vines. Journal of Horticultural Science 69, 339–350. doi:10.1080/14620316.1994.11516463. Source for: the optimum leaf area index on a T-bar. Title and secondary account in [2] used.
• [11] Snelgar, W.P. and Martin, P.J. (1997). Relationship between leaf area index and fruit size in kiwifruit. Acta Horticulturae 444, 199–204. doi:10.17660/ActaHortic.1997.444.29. Source for: the relationship between leaf area index and fruit size. Through the account in [2].
• [12] Buwalda, J.G. (1991). A mathematical model of carbon acquisition and utilisation by kiwifruit vines. Ecological Modelling 57, 43–64. doi:10.1016/0304-3800(91)90054-5. Source for: the carbon allocation modelling that underpins the target leaf area index of 3 to 4. Through the account in [2].
• [13] Grant, J.A. and Ryugo, K. (1984). Influence of within-canopy shading on fruit size, shoot growth, and return bloom in kiwifruit. Journal of the American Society for Horticultural Science 109(6), 799–802. doi:10.21273/JASHS.109.6.799. Source for: the effect of within-canopy shading on fruit size and return bloom.
• [14] Snelgar, W.P., Hopkirk, G., Seelye, R.J., Martin, P.J. and Manson, P.J. (1998). Relationship between canopy density and fruit quality of kiwifruit. New Zealand Journal of Crop and Horticultural Science 26, 223–232. doi:10.1080/01140671.1998.9514058. Source for: the relationship between canopy density and fruit quality.
• [15] Miller, S.A., Broom, F.D., Thorp, T.G. and Barnett, A.M. (2001). Effects of leader pruning on vine architecture, productivity and fruit quality in kiwifruit (Actinidia deliciosa cv. Hayward). Scientia Horticulturae 91(3-4), 189–199. doi:10.1016/S0304-4238(01)00259-X. Source for: leader pruning as a divided-canopy technique and its effects on architecture and quality.
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• [20] McAneney, K.J., Judd, M.J. and Trought, M.C.T. (1984). Wind damage to kiwifruit (Actinidia chinensis Planch.) in relation to windbreak performance. New Zealand Journal of Agricultural Research 27, 255–263. doi:10.1080/00288233.1984.10430427. Source for: the relationship between wind damage and windbreak performance.
• [21] Mauri, S., Cellini, A., Buriani, G., Donati, I., Costa, G. and Spinelli, F. (2016). Optimization of cultural practices to reduce the development of Pseudomonas syringae pv. actinidiae, causal agent of the bacterial canker of kiwifruit. Journal of Berry Research 6, 355–371. doi:10.3233/JBR-160115. Source for: the link between a dense canopy and more severe bacterial canker, the benefit of an open canopy in irradiation, aeration and penetration of treatments, and the relationship with excessive nitrogen fertilisation. Abstract and institutional repository record used, not the full text.
• [22] Costa, G., Ferguson, R., Huang, H. and Testolin, R. (2018). Main changes in the kiwifruit industry since its introduction: present situation and future. Acta Horticulturae 1218, 1–16. doi:10.17660/ActaHortic.2018.1218.1. Source for: the predominance of pergola training with strip males among top-performing New Zealand growers. Through the account in [2].
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• [27] Savian, F., Ginaldi, F., Musetti, R. and colleagues (2020). Studies on the aetiology of kiwifruit decline: interaction between soil-borne pathogens and waterlogging. Plant and Soil 456, 113–128. doi:10.1007/s11104-020-04671-5. Source for: the interaction of soil-borne pathogens and waterlogging in the aetiology of kiwifruit vine decline. Abstract and bibliographic record used, not the full text.