Sebastian Soppelsa

Intercropping is considered a biodiversity-promoting practice and consists of the simultaneous cultivation of multiple crops in the same field. Despite its ecological benefits, its adoption in specialized farming systems—such as strawberry monocultures—remains limited, as these systems typically focus on maximizing income from a single crop. The experiment investigated the effects of intercropping strawberry (Fragaria × ananassa) with herbs such as chives (Allium schoenoprasum L.), marigold (Calendula officinalis L.), peppermint (Mentha × piperita L.), strawberry mint (Mentha suaveolens Ehrh.) and common sage (Salvia officinalis L.), using a 2:1 strawberry-to-herb ratio. Conducted over two consecutive years (2021–2022) in the alpine environment of Martell Valley (South Tyrol, Italy), the study assessed plant growth, fruit production, biological and economic feasibility, and the impact of intercropping on beneficial species, including pollinators, pests, and predators. Our results showed significant year-to-year variation. Although strawberry plants intercropped with herbs in 2021 achieved a fruit production that was not significantly different from that of pure stand (on average 150 g plant⁻¹), the intercropping systems outperformed monocropping as revealed by indices such as land equivalent ratio (LER) and income equivalent ratio (IER) both greater than one. However, in the second year of cultivation (2022), the main parameters showed a decline. For example, strawberry plant biomass was decreased (by an average of 33%) in intercropping combinations involving chives, calendula and peppermint, resulting in a reduction in strawberry production of over 50% compared to monoculture. Indeed, the interaction between different plant species analyzed with competitive indices showed that strawberry plant appeared as the dominated crop in those combinations (aggressivity for strawberry: Af < 0; competition ratio for strawberry: CRf < 1). In both years, leaf nutrient content in intercropped strawberry plants was statistically similar to that of monocropped plants. Conversely, significant differences were observed in intercropped herbs (e.g., K + 50% and S + 30% in marigold and chives leaves, respectively). Intercropping systems, especially with chives and marigold, increased the richness of arthropod species (+100% as compared to strawberry in pure crop). Our research work contributes to a better understanding of the biological and economic feasibility of intercropping as a diversified farming practice for a strawberry farm. Furthermore, our findings offer a foundation for further investigations into interspecies interactions, particularly in terms of enhancing pollinator attraction and pest repulsion.

Finding safe and reliable alternatives to fungicides is currently one of the biggest challenges in agriculture. In this regard, this experiment investigated the effectiveness of different elicitors, botanical extracts and essential oils to control grey mold (Botrytis cinerea) and powdery mildew (Podosphaera aphanis) on strawberry plants. This trial was conducted in field conditions under a plastic tunnel with strawberry plants ‘Elsanta’. A first group of strawberry plants was treated before flowering with elicitors [acibenzolar-S-Methyl–(BTH), chitosan], botanical extracts (seaweed extract, alfalfa hydrolysate) and essential oils (thyme and juniper), and grey mold incidence on flowers was evaluated (Experiment 1). Furthermore, a second group of plants was treated before (Experiment 2) and after (Experiment 3) controlled inoculation with P. aphanis. The results indicated that the incidence of flower infected by B. cinerea was reduced by approximately 50% with thyme and juniper essential oils’ applications compared to the untreated control, with no significant difference observed compared to the commercial fungicide penconazole (positive control). As a consequence, the final yield of essential-oil-treated plants was +27% higher than that of non-treated plants. No significant differences emerged for other tested products against grey mold. However, gene expression analysis showed an up-regulation (>2 ÷ 5 folds as compared to control 4 days after application) of FaEDS1, FaLOX and PR gene expression (FaPR1, FaPR5, FaPR10) in leaves treated with BTH. The other natural substances tested also induced defense-related genes, albeit at a lower level than BTH. In Experiment 2, all treatments applied prior to inoculation significantly reduced the incidence and severity of powdery mildew as compared to control. At 28 days after inoculation, chitosan and thyme essential oil applications performed similarly to their positive controls (BTH and penconazole, respectively), showing a significant reduction in disease incidence (by −84 and −92%) as compared to control. Post-inoculum application of essential oils (Experiment 3) showed an efficacy similar to that of penconazole against powdery mildew. These results indicated that the tested substances could be used as alternatives to fungicides for the control of grey mold and powdery mildew in strawberry, therefore representing a valuable tool for the control of these fungal diseases under the framework of sustainable agriculture.

Finding, safe and reliable alternatives to fungicides is one of the most actual challenges in agriculture. In this regard, our experiment investigated the effectiveness of different elicitors, botanical extracts and essential oils to control grey mould (Botrytis cinerea) and powdery mildew (Podosphaera aphanis) on strawberry plants. Furthermore, the defence mechanisms activated in plants after treatments were investigated. The trial was conducted in field conditions under plastic tunnel with strawberry plants ‘Elsanta’. In the first experiment, a group of strawberry plants was treated before flowering with elicitors [acibenzolar-S-Methyl – (BTH), chitosan], botanical extracts (seaweed extract, alfalfa hydrolysate) and essential oils (thyme and juniper) to evaluate their ability to reduce the incidence of grey mould infection on flowers. In the second experiment, another group of plants was treated before and after experimental inoculation with P. aphanis. Results indicated that the incidence of flower infected by B. cinerea was significantly reduced by thyme and juniper essential oils, showing values that were not significantly different from the commercial fungicide penconazole (positive control). As a consequence, final yield of essential oil-treated plants was +27% higher as compared to control. No significant differences emerged for other tested products against grey mould. However, gene expression analysis showed an up-regulation of FaEDS1, FaLOX and PR gene expression (FaPR1, FaPR5, FaPR10) in leaves treated with BTH. The other tested natural substances also elicited defence-related genes, however at a lower level than BTH. In the experiment, all treatments applied prior inoculation significantly reduced the incidence and severity of powdery mildew as compared to control. At 28 days after inoculation, chitosan and thyme essential oil applications performed similarly to their positive controls (BTH and penconazole, respectively), showing a significant reduction of disease incidence (by -84 and -92%) as compared to control. Post-inoculum application of essential oils showed similar effective action to fungicide (penconazole) in reducing incidence and severity of powdery mildew. These results indicate that the tested substances could be used as alternatives to fungicides for the control of grey mould and powdery mildew in strawberry, therefore representing a valuable tool for the control of these fungal diseases under the framework of the sustainable agriculture.

Optimizing profitability is a challenge that strawberry farmers must face in order to remain competitive. Within this framework, plant density can play a central role. The aim of this two-year study was to investigate how planting density can induce variations in plant growth and yield performances in an alpine mountain strawberry cultivation (Martell Valley, South Tyrol, Italy), and consequently quantify the farm profit. Frigo strawberry plants cv. Elsanta were planted in soil on raised beds and subjected to five different planting density levels (30,000 and 45,000 as large spacing; 60,000 as middle spacing; 90,000 and 100,000 plants ha⁻¹ as narrow spacing, corresponding to a plant spacing of 28, 19, 14, 9, and 8.5 cm, respectively). Our findings indicate that the aboveground biomass in plants subjected to low planting density was significantly increased by +50% (end of first year) and even doubled in the second year in comparison with plants in high planting density. Those results were related to higher leaf photosynthetic rate (+12%), and the number of crowns and flower trusses per plant (+40% both) (p < 0.05). The low yield (about 300 g plant⁻¹) observed in the high planting density regime was attributable to smaller fruit size during the first cropping year and to both a reduced number of flowers per plant and fruit size during the second year (p < 0.05). Although the highest yield (more than 400 g plant⁻¹) was obtained with wide plant spacing, the greatest yield per hectare was achieved with high planting densities (28 t ha⁻¹ in comparison with 17 t ha⁻¹ with low plant density level). However, the farm profit must take into account the costs (especially related to the plant material and harvesting costs) that are higher under the high planting density compared with the other density regimes. Indeed, the maximum farm profit was reached with a density of 45,000 plants ha⁻¹ which corresponded to EUR 22,579 ha⁻¹ (over 2 years). Regarding fruit quality, fruits coming from the low plant density level showed a significantly higher color index (+15% more red color) than fruits from high plant density (p < 0.05). In conclusion, our results suggest that a middle planting density can be a fair compromise in terms of plant growth, yield, and farm profit.

Apple fruits are susceptible to pathogenic fungi such as Botrytis cinerea and Penicillium expansum which are responsible for significant pre- and postharvest fruit losses. Given the strong restriction in the use of synthetic agrochemicals, especially during the postharvest phase, alternatives are currently sought for a more sustainable management of apple storage. The antifungal activity of thyme, clove, anise, camphor, and juniper essential oils (EOs) was evaluated with in vitro tests and the minimum inhibitory concentration (MIC) was determined. Thyme and anise EOs showed a MIC value of 0.5 and 1 mL L⁻¹ against B. cinerea, respectively. A MIC of 0.5 mL L⁻¹ was found for clove EO against P. expansum. Camphor and juniper EOs were found to be less effective. Although in those experiments the antifungal activity of EOs was proven, when EOs were applied in in vivo conditions they did not demonstrate the same effectiveness. In order to preserve EO inhibitory performances, edible coatings combining polysaccharide matrices (chitosan, arabic gum, and xanthan gum) with EOs were tested. After considering consistency, uniform coverage of the fruit surface, and antifungal properties of the matrix, chitosan was identified as the most suitable component for EO encapsulation. Treatments with chitosan in combination with thyme EO on apple fruits (cv. ‘Braeburn’) showed inhibitory effects on infection caused by B. cinerea (−48% of infected wounds compared to untreated). Similarly, clove EO combined with chitosan reduced the Penicillium infections in apple cv. ‘Golden Delicious’ by 62%. These results therefore suggest the effectiveness of the use of EOs encapsulated with chitosan for the control of postharvest diseases of apple fruits during storage.

Crop decline caused by soil borne fungal pathogens affects specialized cropping systems such as fruit trees and strawberry. A study was carried out to investigate the effectiveness of pre-plant application of waste-derived biomasses in strawberry (Fragaria × ananassa) to reduce that phenomenon. A field experiment was carried out in an alpine strawberry specialized valley in South Tyrol (Italy), in a long term cultivated field selected for yield reduction over recent years. In July 2018, one month before strawberry transplanting, a field experiment with four soil treatments was set up: anaerobic digestate (solid fraction) of liquid manure, compost from anaerobic digestate of organic fraction of municipal solid waste (OFMSW), untreated control and Dazomet as chemical control. Plants were grown for two cycles (2019 and 2020). Dazomet always gave a significant (over 50%) increase in marketable yield per plant in both the years, anaerobic digestates did not improve strawberry production; compost from OFMSW gave phytotoxic effects in the first year, but improved strawberry yield like Dazomet in the second. Changes of rhizosphere bacterial populations and difference in root pathogen abundance, especially that of Dactylonectria torresensis, were correlated to the crop response to treatments. Findings suggest that waste-derived biomasses are a promising eco-friendly option for counteracting strawberry yield decline. Their positive impact was mostly linked to functional improvements induced by microbial variations. However, the use of such organic amendment requires careful evaluation of composition, doses and above all application times to reduce phytotoxic effects that in some cases can occur in the first months after application.

Nutritional unbalances, such as calcium deficiency at the fruit level, are generally the causative agent of post-harvest disorders in apples. Foliar application of Ca as calcium chloride is the current solution to increase Ca concentration in apples, even though the effectiveness of this approach is often not satisfactory. In this research, we tested the efficacy of a combined application of Ca with selected biostimulants to improve apple quality and to reduce the incidence of storage disorders. The experiment was conducted in two “Jonathan” apple orchards that differed in management systems and characteristics. Tree canopies were sprayed with calcium chloride alone and in combination with a commercial product containing zinc and silicon or a seaweed extract. The seaweed extract increased apple quality by boosting the reddish coloration (+32% of color index) and by enhancing final anthocyanin concentration of fruit skin. Both biostimulants significantly reduced (by 20%) the incidence of the physiological disorder, known as “Jonathan spot”, after 160 days of storage. Increased concentration of nutrients (Ca, Zn, and Mn) in the skin of apples after biostimulant applications, together with changes of the phenolic profile during the storage, are discussed as the possible causes of the reduced fruit susceptibility to post-harvest disorders.