Pistacho Pro's technical director, Mario González-Mohino, travelled to California together with Esaú Martínez Burgos, a researcher at IRIAF-CIAG El Chaparrillo, and two growers from Toledo and Ciudad Real to follow the full Californian pistachio cycle, from nurseries, orchards and field trials through to harvesting, processing and marketing. The visit formed part of a study carried out with the University of California, Davis on sustainability and carbon capture in the crop.
As regards plant material, the UCB-1 rootstock, derived from the cross between Pistacia atlantica and Pistacia integerrima, remains the backbone of Californian production and is regarded as the best option against verticillium wilt, although drainage and water management continue to be decisive. The delegation also became acquainted with the clonal rootstock Platinum, obtained from the reverse cross, and with four high-vigour clones at Duarte Nursery — V211, V214, D110 and D71 — which, according to nursery trials begun in 2015, developed canopies around 20 % larger and yields between 30 % and 32 % higher than seed-propagated UCB-1. Pistacho Pro warns that greater vigour also entails greater requirements, and that genetics cannot compensate for a poorly chosen plot or mistaken management.
Much the same applies to varieties. Kerman retains a significant share, although Golden Hills is increasingly present in new orchards owing to its early entry into production, earlier harvesting and suitability for mechanised designs. Under certain Spanish rain-fed conditions or on poor soils, however, this variety has shown problems of fruit set and cluster abortion, which leads the company to argue that varietal performance cannot be assessed in isolation from the rootstock, the soil, the climate, water, nutrition and pollination.
Water accounts for a large share of the difference in yield. Several holdings were applying volumes close to 9,000-10,000 cubic metres per hectare, with figures of up to 12,000 also mentioned, against one particular case of localised irrigation using 2,000-2,500 cubic metres, which is not representative of the state as a whole. Nor is there a single view there on how irrigation should be calculated: some approaches are based on the water lost by the soil and the plant, others on standard tables according to tree age, increasingly supported by sensors, drones and dendrometers.
One of the trials that attracted most interest compared three pruning systems in Golden Hills on UCB-1: a conventional three-branch open vase, a modified central leader and minimal intervention. After five harvests, the latter two showed the highest cumulative yields and fewer blank nuts, as well as bringing forward entry into production by one year, reaching some 500 kilograms per hectare in the first harvest. The conclusion drawn by Pistacho Pro is not that pruning should be abandoned, but that every cut should be justified.
California has not resolved alternate bearing either, with yields reported at around 1,500 kilograms per hectare in weak seasons and between 4,000 and 4,500 in good years, which determines the number of harvesting passes. Mechanisation, which is highly developed, works because it is decided at the point of orchard design and tree training, while the processing industry makes the greatest difference: at TOMRA the delegation saw equipment capable of separating split and closed nuts, detecting external defects, identifying internal problems by X-ray and recovering sound product from rejects.
The findings of the visit were shared with the wider sector on 22 July through a free webinar entitled "Pistachios in California: lessons from Pistacho Pro", in which Mario González and Esaú Martínez set out the main conclusions of their trip to the American state, a world benchmark in the cultivation and marketing of this nut. The session, held within the framework of the World Pistachio Congress, offered a first-hand account of what was seen on the ground through images, videos and reflections on the possible application of the Californian model in the Spanish and European context, and was open to all those with an interest in pistachio growing, production and business.
For Pistacho Pro, the central lesson is that the Californian model does not rest on any single technique, but on the coordination of genetics, water, soil, pruning, crop protection, harvesting and processing. Following rapid growth in planted area, the challenge for Spain lies in achieving more regular yields, processing to a high standard, marketing more effectively and building a recognisable identity for Spanish pistachios.
Sentido Común Internet
Agrifood Comunicación