In order to research sustainable production methods, improve the qualitative and quantitative aspects of production, and counteract the most serious biotic and abiotic challenges affecting cherry cultivation (Drosophila suzukii and fruit cracking in particular), a four-year project (2021-2024) was initiated to investigate the most innovative physical protection methods available (Monari 2021).
Specifically, the goal was to analyze the main features of multifunctional block systems, which are structures made with rain-proof coverings completed by insect-proof netting around the perimeter. Compared to multifunctional single-row systems, which have already been extensively tested (Ghelfi 2016, Caruso 2019, Morandi 2022) but are not particularly widespread in Emilia-Romagna, the block system was considered a more suitable alternative for regional cherry farms.
The ongoing activity is carried out through a partnership between the Vignola IGP Cherry Consortium, the Modena Phytosanitary Consortium, and the University of Bologna. Financial support for the development of experimental systems and research activities comes from the Emilia-Romagna Region, the Municipality of Vignola, and, in the last two years, the “Smile project” coordinated by Rinova.
The multifunctional structures were set up at experimental fields owned by the Municipality of Vignola, granted free of charge to the Vignola Cherry Consortium in the Province of Modena, an area renowned for its specialization in cherry orchards and the high quality of the product (IGP certification).
The main technical aspects investigated in the project are listed below:
Image 1.
The investigations were carried out on three experimental systems. The first block system was built in 2021 on a cherry plot with a varietal comparison trial covering about 6000 m². The rain-protection netting was double-layered and complemented by a perimeter anti-Drosophila net (1 mm²).
The second system was built in 2022 on a plot featuring a rootstock trial grafted with different varieties over approximately 6000 m². Four different ultra-dense single-layer and double-layer net materials were compared, sealed on the perimeter with anti-Drosophila netting. Finally, in 2024, in the same experimental area, two block systems with ultra-dense single-layer netting were installed on organic cherry cultivation plots.
This work reports some partial results from ongoing activities, focusing on the first experimental system built in 2021 with a “double-layer rain-proof net.” A complete summary of the activities will be included in a publication at the end of the four-year experiment. The covering system was implemented in a varietal collection of cherries with over 80 cultivars and selections under evaluation, planted in 2014. The orchard spacing is 5.0x2.6 m, with Colt rootstock and free palmette training form.
The multifunctional covering was installed in late April 2021, just before the onset of veraison for the earliest cultivars. An anti-Drosophila net (1.18 x 0.97 mm) was integrated, with a double overlay net made of Microtex Acqua Stop® for rain protection on the upper part.
The system included a double entrance door and special corridors at the plot ends to maximize structural airtightness. Inside the covering, a data logger was installed to collect main microclimatic data (temperature, relative humidity) at approximately 2.5 meters in height. Leaf wetness was calculated using relative humidity data >80%. Four plastic tanks were placed to collect water and check the covering material's impermeability, while a rain gauge was installed outside the system.
The shading caused by the multifunctional covering system was quantified using an AccuPAR LP-80 ceptometer. This device measured the photosynthetically active radiation (PAR) intercepted by the covering's different components. Finally, traps were set up to monitor D. suzukii and cherry fruit flies.
Damage assessments from cracking, D. suzukii, and cherry fruit flies were compared with an uncovered neighboring orchard of the same age managed under Integrated Production with similar agronomic and phytosanitary practices recommended by the same advisory agency.
The cultivars used for comparative analyses were eight: Burlat, Sweet Ariana, Sweet Lorenz, Samba, Grace Star, Ferrovia, Lapins, and Staccato, with different ripening periods covering the entire production span (mid-May to early July), selected among the most widespread and appreciated by producers in the Vignola area.
For fruit cracking, three trees of comparable vigor and production load were selected for each cultivar, identifying 5-6 branches with a diameter of 30-40 mm at 1.5-2.0 meters height. All fruits on these branches were analyzed, dividing them into healthy and cracked ones.
On average, about 300 fruits per trial were counted. For D. suzukii, adult captures were monitored weekly, and the presence of egg deposits and larvae was assessed on a 100-fruit sample per cultivar under a binocular microscope.
Image 2.
The results obtained from the investigation conducted during the 2021–2023 period highlight the microclimatic characteristics achieved with the "double-layer" Acqua Stop® monoblock configuration. To simplify interpretation and enhance the immediate understanding of the information, the microclimatic data are presented as aggregated and expressed as the general daily average.
Regarding temperature, a reduction compared to the uncovered setup (Image 3) is noted due to the shading effect induced by the covers, which was particularly evident in 2023 (a reduction of about 2 °C). On the other hand, there was an increase in relative humidity in the monoblock network compared to the uncovered setup, with an average increase of approximately 7% °RH over the three years (Image 4).
Additionally, an increase in leaf wetness (expressed as the number of hours with °RH >80%) was observed in the monoblock network compared to the uncovered setup (Image 5).
Image 3: Effects of monoblock covers on the daily average air temperature (°C) compared to the uncovered cherry orchard.
Image 4: Effects of monoblock covers on the daily average air Relative Humidity (°RH) compared to the uncovered cherry orchard.
Image 5: Effects of monoblock covers on the daily average air Leaf Wetness (°RH >80%) compared to the uncovered cherry orchard.
The cover used in the trial consists of an anti-drosophila net placed above the row spacings, with a shading power of 16%. This net is integrated, above the rows, with a double-layer Microtex net, Acqua Stop® model, which serves as a rainproof net and has a shading power of 62% of transmitted light. The proportions between the two types of nets are 1:1, with 2 meters covering the row spacings and 2 meters covering the plants on the rows.
Data obtained from a similar trial, although with a different species (apple, Boini et al., 2023), showed that despite the high shading power of the rainproof net, the integration of these two types of nets resulted in high levels of diffuse light, limiting the amount of direct light intercepted by the cherry plants during the hottest hours of the day.
This allowed for the maintenance of full carbon assimilation functionality, without reducing the plants’ photosynthetic activity, while limiting transpiration. This configuration enables the reduction of irrigation inputs, consequently increasing irrigation efficiency.
The average reduction in cracking damage across the eight cultivars tested (Image 6) observed in the covered setup compared to the uncovered control is significant, with percentages varying based on the rainfall of the year considered. Specifically, in 2023, during the cherry harvest period (May–June), nearly 400 mm of rain was recorded, causing severe damage (about 60% cracking) in the uncovered setup, while in the monoblock, the average cracking incidence was limited to 16%. The rainproof cover in the trial demonstrated a waterproof level just below 100% (Image 7).
Image 6: Average % cracking of the 8 cultivars tested and rainfall recorded during the 2021–2023 period (May–June).
Image 7: Average waterproofing of the “Acqua Stop®” cover measured during the 2021–2023 period (May–June).
In Image 6, results related to the damage caused by D. suzukii are presented as an average across the eight cultivars tested. Full control of the insect was achieved using multifunctional nets compared to the uncovered orchard managed with traditional chemical insecticide protection.
This is also confirmed by the capture data (Image 6), which are zero in the covered setup compared to the uncovered orchard. Full control of the Asian fruit fly with multifunctional nets was achieved with a reduction in insecticides of over 75% (Image 7), taking as a reference the protection used on a late cultivar such as Lapins.
The netting strategy involves closing the setup just before the start of the coloring stage of the earliest cultivar. Following this, two insecticide treatments are applied to eliminate the residual population in the protected environment. The system's effectiveness is verified through flight monitoring and the presence of egg-laying on fruits nearing ripeness.
The reduction in fungicide treatments for fruit monilia control is less pronounced than for insecticides and is influenced by seasonal climatic conditions. In fact, despite a reduction in cracking damage compared to the uncovered setup, an increase in relative humidity was observed, creating favorable conditions for fruit monilia infections.
Finally, no issues were recorded related to other adversities, given the full control of cherry flies, Asian stink bugs, bird damage, and red spider mite infestations.
Image 8: Average damage caused by D. suzukii on the eight cultivars tested during the 2021–2023 period.
Image 9: Trend of D. suzukii captures observed in the uncovered plot during the 2021–2023 period. No captures were recorded in the monoblock.
Image 10: Percentage reduction in insecticides and fungicides in multifunctional covers compared to uncovered setups on a late cultivar (Lapins). Data relate to May–June (2021–2023).
The results obtained during the three years of experimentation can be considered positive and promising for validating multifunctional protections and the subsequent widespread use of this technique. While the single-row model has already been validated with solid information highlighting its strengths and weaknesses, this study focused on the monoblock system. Below is a summary of the main results:
Image 11.
The information collected is already quite comprehensive, and the proposed technique has proven effective in addressing significant issues such as cracking phenomena and infestations of the Asian fruit fly, with significant reductions in insecticide use. The activity is ongoing, so the results obtained thus far will need to be confirmed in the coming years of experimentation. It will also be necessary to obtain additional information regarding other side effects, including potential infestations of black aphid, red spider mite (Tetranychus urticae), and the Asian stink bug.
It will therefore be interesting to further explore the effects of shading from the coverings and aspects of plant physiology, as well as costs and relative economic viability. Additionally, the evaluation of new single-layer protection models will continue in terms of their applicability and economic convenience compared to the double-layer system. Finally, investigations into the potential use of multifunctional coverings to achieve satisfactory results under organic farming conditions will be completed.
Source: S. Caruso, L. Casoli, V. Monari, I. Ansaloni, L. Manfrini, What are the positive effects of monoblock nets on cherry trees? L’Informatore Agrario, 2024.
Images: SL Fruit Service, Consorzio Fitosanitario di Modena, Regione Emilia Romagna
Stefano Caruso, Luca Casoli - Provincial Phytosanitary Consortium of Modena
Valter Monari, Ivan Ansaloni - Vignola I.G.P Cherry Consortium
Luigi Manfrini - Department of Agro-Food Sciences and Technologies, University of Bologna
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