Climate change and the increase of extreme climatic events is causing large losses in all crops, with emphasis on those that are more delicate like soft fruits, such as berries, cherries, grapes and more, and which have the highest commercial value, says Dr Duque, who works for Daios Plastics: “Protecting soft fruits from hail, rain, strong winds, sunburns, excess of temperature and radiation is and will be essential in the future. However, benefits do not stop here but continue by increasing photosynthesis rates through appropriate light management and plant stress what enhances yields and fruit quality.”
Over the past four decades the company has managed to expand into several European countries, Dr. Duque explains. “We, at Daios Plastics, have been developing products and solutions for the main agricultural challenges for more than 40 years in several countries like Greece, Italy, Germany, the UK, Netherlands and Israel. Innovation and cooperation with our customers is deep in our DNA. Specifically, we’ve been protecting soft fruits with this Safe-D system in single row cover since the 80’s; first crop was table grapes, and then the know-how acquired has been transferred to other delicate crops like blueberries, raspberries, and lately to kiwis and cherries too.”
Dr. Duque states that the product that Daios provides is a great solution to prevent damages from rain and other weather conditions. “The cracking caused by rain in cherries is one of the great problems that can strongly affect the production and profitability of an orchard. Over the years, different solutions have been sought to face this problem. The most common has been the implementation of different types of covers, polyethylene (PE) films of different densities and compositions, raffia or other materials that help avoid direct contact of rainfall with the fruit, which greatly reduces the risk of losses quite successfully. Furthermore, if mechanical and optical properties of the material are the appropriates, it also brings other very positive effects to the production.”
When asked about specific examples, Dr. Duque remembers the situation in Spain: “In the last few years in Spain, cherry production in many regions has been severely affected by rains, which has had a very negative economic impact on the growers. Furthermore, we have here another handicap which are the strong winds many regions from the Iberian Peninsula suffer. This is the case of several cherry production areas located in the Ebro Valley, where the famous ‘Cierzo’, with constant winds of 50-60 km/h and maximum wind gusts of more than 100 km/h, makes the installation and success of these type of systems more challenging.”
Dr. Duque continues with his explanation: “As you have noticed, we always talk about a system; you may have a very strong and solid structure, but with a weak film, the whole process doesn’t work, and vice versa. It goes hand on hand, and this is why our first step is always identifying who are the best constructors of these type of poles and cables roof structures, and to work closely together and transfer them our experience and knowledge acquired in previous experiences. Of course, every country and every region have its own characteristics, therefore these strong partnerships are key for the success of the project.”
“In Spain we work exclusively with Agrigán in Aragón and North of Spain and with Agromalla in Cataluña and East. We‘ve been optimizing the system for the last two years against strong winds, and we feel very happy about the results this first year we are commercially present in these regions. 2021 has been a key for the system in Spain; we have got many challenges, as the climate in winter and spring has been rough, but the system has shown its robustness. Furthermore, the absence of cracking and the increase in fruit quality has been observed by all customers.”
“Regarding the robustness of the system, aside from the great job done by the constructors, one of the key reasons is the extraordinary mechanical properties of the film, with eyelets thermo-fused to the film and a gradual variation in thickness that confers to the system a very high resistance against strong winds.” Dr. Duque emphasizes.
For cherries, together with Agrigán and Agromalla, Daios Plastics has covered around 40 ha in total, most of them in Aragón and Cataluña. “The first question is always ‘what does the grower want to achieve?’ For example, it is not the same if one wants ‘only’ protection against adverse climatic events like rain, hail or winds. Or if precocity is also required. The structure and the film will vary in each case.”
Dr. Duque continues: “There is a lot of misunderstanding and noise in the market about plastic covers; if they increase or decrease the temperature, if they soften the fruit, if they induce earliness and so on; In his opinion there is a need to further educate the market when it comes to these novel products. He continues, there is a lot to be done here and together with Agrigán and Agromalla we want to change this and will start giving technical courses as of next month. This will help our customers to gain more knowledge on these types of systems and how to manage them to extract the whole potential they have.”
“Plastic films in general, and this system in particular can be very successful, as long as we know the optical properties of the cover and the design of the system is the right one. Furthermore, agronomic management under a protective structure is completely different. Irrigation can drop up to 50% and nitrogen supply also needs to lower drastically. Under the covers, the trees feel very comfortable and have much less stress, therefore one needs to cut water and fertilization, otherwise it develops much more vigor, especially in combination with highly vigorous rootstocks.”
It is all about light management and convection, Dr. Duque says: “For example, when we are looking for earliness, the film incorporates long wave IR absorbers to increase inside temperature inside absorbing and re-emitting the heat the plants and the ground emits. To maintain this gained thermal energy, we close the perimeter with an easy retractable film, so when late in March or April the temperature goes up we can open the perimeter and ventilate fast. Here we simulate a kind of retractable greenhouse.”
The system means that even when there is cold and cloudy weather, one can speed up the process to harvest, Dr. Duque states: “This year, with this system we have managed to obtain an earliness of about 15 days in the harvest. This is extraordinary, as weather in April was cold and cloudy, and outside the rate of photosynthesis was very low whereas inside the tree was operating at much higher rate. In more normal years we count with 7-9 days of precocity. This changes the whole profitability for the grower, especially in already early production areas.”
“Fruit protection under Safe-D system has been established in other countries as an essential tool in the increase of profitability in some crops such as grapes, cherries and berries, and we are very grateful to our customers for allowing us to establish this system through our partners Agrigán and Agromalla in Spain too.” Dr. Duque concludes.