In today’s newsletter we wish to tackle the great dilemma kiwifruit growers face: pergola or tendone?
Two completely different ways of approaching the topic, almost two lifestyles, depending on kiwi plant unique behaviour compared to any other fruit.
We do not expect, simply within the space of this article, to draw definitive conclusions on the topic by identifying undoubtedly the best system; instead, we want to take a comparative approach, sharing with you the experience of two of our customers who have been using either one of these systems in their orchards for years now. First of all, we must start by talking a little about the kiwi plant itself, to understand how it differs from other fruit plants and therefore define its needs, a key point for the success of any type of system.
The kiwi fruit is a climbing plant, generally grown in a permanent cordon from which shoots of different lengths starts, with their flower buds forming on their distal part for the following year. Normally the productive shoots are renewed annually, therefore the weight of the vegetation and production lies entirely on the supporting structure. Hence the need for a more complex supporting system compared to the Superspindel for apples, capable of providing greater support for both branches and fruit. Our design calculations shall moreover consider the imposing foliage the Actinidia develops, whose weight considerably stress the structure (especially when leaves will be heavy with rainwater).
It is on the basis of these considerations that the Tendone was created, which is essentially a dense tangle of wires and ropes aimed at building a supporting network for the shoots and the fruit. The post scheme is usually five metres between the rows and five metres along the rows, with supporting cables on each transversal connection (diameter varying between 6 and 7 mm) and six longitudinal wires to support the shoots (one every eighty cm or so), with a diameter of 3 mm. The fruits will therefore spread below the cables, hanging free from the leaves and shoots, thus reducing the occurrence of any diseases.
A great supporter of this type of system is our customer Vitor Araujo, who has been using the tendone as a supporting system since the 1980s on his Kiwi Green Sun farm in Guimaraes, in northern Portugal, becoming the largest kiwi producer on the Iberian Peninsula in 2008. Today, Kiwi Sun has a network of thirty-two contributing producers, with a cultivated area of more than three hundred and twenty hectares. With a production that in some cases reaches peaks of forty tonnes per hectare, Vitor’s target of reaching ten thousand tonnes of kiwis per year is not far off. This goal is also pursued using the tendone, which allows a better yield per hectare, given the different weather conditions in Portugal compared to Italy (particularly for the number of cold hours per day).
Vitor’s choose a tendone system from the very beginning, since it provides the plant with a strong supporting system that prevents the shoots from touching the ground and consequently any disease that may derive, ensuring at the same time greater effectiveness in the treatment for healthy kiwi leaves. The kiwi fruit hangs below the leaves but is free from them so that it can ripen at its best, while benefitting from the shade leaves can offer that avoid sunburn from the intense Portuguese sunlight. Last but not least, harvesting becomes considerably easier since the workers can now rapidly pick the kiwis that are at the ideal height.
Antonio, Propomar’s owner, Vitor’s trusted installer and authorised Valente dealer in Portugal, has also given us his opinion as a technician, stating that the tendone is the system that best suits Portugal’s morphology characterised by small, terraced plots, which can therefore be covered for almost 100% of their surface with this type of structure, without wasting any space.
An undeniable set of advantages for our tendone system, that allowed Vitor and Kiwi Sun to reach their ambitious goals and then might be really a precious experience to share with other kiwi-producers.
Let us now compare it with the other system, that is the pergola.
The basic principle is very similar to that of the tendone, with the same number of cables supporting the shoots (from four to six) which in turn are supported not by transversal cables but by galvanised steel brackets of varying size and width depending on the variety of kiwi (straight, curved, sloping for yellow, green, or red kiwi). The bracket must provide a considerable load-bearing capacity to meet the needs of each plant and be firmly and steady attached to the pole with its specially shaped connector. The tension on the supporting wires is provided by head bracket wire-tensioner, a metal structure that is much stronger compared to the intermediate ones, which can support the stringing effort. The shoots can therefore enjoy the same support as with the tendone, with the fruit developing particularly close to the ends of the brackets; it is therefore important for each variety to be provided with the appropriate bracket.
The main advantage of this type of system lies in the possibility to manage the net, which remains accessible for the seasonal opening and closing operations, an option that in a tendone system is compromised by the growth of the shoots.
The strong point of the pergola system is that it is easy to provide access along the rows, between the pergolas brackets, for various height mechanical equipment (cab tractors, mechanical pruning machines, forklifts, hydraulic platforms for the management of annual winter closing operations of the nets or any relevant extraordinary maintenance operations). Another aspect that should not be underestimated, particularly for the new Club varieties (cultivars), are the specifications that require a reduction in the quantity of kiwifruit per hectare in order to increase their brix (sugar content) and dry matter, an assessment that also involves both the supporting system and agronomic and environmental variables.
We interviewed our customer Riccardo Adami of Società Agricola Adami, who has been using the pergola in his farm in Dossobuono (VR) for almost ten years now, with excellent results. He has used two-metre curved brackets on the green kiwi, obtaining a production of around thirty tonnes per hectare with an excellent sugar level thanks to the perfect sunlight provided by the pergola support, which allows light to pass under the foliage, thus increasing the quality of production. The plant shoots are tied back about every twenty centimetres, leaving fifteen sprouts, and cutting about fifty centimetres from the ground, a simple and cost-effective job that guarantees the best management of the orchard. In 2019, Riccardo and his brother Alessandro decided to convert one of their old Valente peach orchards to Kiwis, and the wide planting system of six metres allowed them to try out the 3.10mt curved brackets, the latest addition to the Valente brackets range and available since 2016. These brackets, developed specifically for yellow and red kiwi fruit, have a less marked curve than traditional curved brackets, allowing them to better support longer shoots. “The plant looks really good, tidy and clean despite the large size of the brackets, but it’s still too early to talk about the harvest, as the first real test will be this year” says Riccardo.
All of Adami’s farms have been covered with anti-hail nets since 1998, a testament to the farsightedness of our client, a true professional in the agricultural sector. “The nets are all black, except for two hectares covered with grey netting, just to give it a try. But there really is no argument: the black one will always be the best, guaranteeing us excellent durability and the best coverage for the plants,” says Riccardo again.
Once again, therefore, our comparative analysis of the various cultivation systems concludes without a winner; and it could not be otherwise since the choice of the type of system depends largely on both climate and environmental conditions as well as the growing habits of each specific area.
Making a reasoned choice is essential, a choice based on careful planning and quality materials that can guarantee the expected results, with the crucial assistance of skilled technicians and trust-worthy agronomist.
Today we have shared with you two representative experiences out of the many our customers tell us. We will surely continue to collect many more to enrich our expertise and help you always make the best choice.