Greenhouse Strawberry Research Articles

Evaluation of Yield, Fruit Chemistry, and Firmness of Seven Strawberry (Fragaria ×ananassa) Cultivars in an Eastern North Carolina Greenhouse

The combination of increasing costs, climate change, and disease- and pest-related issues present large challenges for the strawberry (Fragaria ×ananassa) industry in the United States. This is especially true for the Southeast, where rain, frost, and a range of foliar, fruit, and soil-borne diseases are prevalent, leading to significant losses every year. Simultaneously, niche winter markets open the opportunity to extend the harvest season, leading to an industry push to use protected culture strawberry production. Tabletop soilless strawberry greenhouse production has the advantage of avoiding soilborne issues while at the same time mitigating weather-related impacts on strawberry yield and quality. The use of long-day cultivars, originally bred for the Central Coast region of California, is currently the industry standard because of desired winter yields. However, short-day cultivars bred for Florida production might also have the potential to produce in winter. In this study, we evaluated the growth, yield, fruit chemistry, and fruit firmness of seven strawberry cultivars that are commonly grown in protected culture in North Carolina: Albion, Brilliance, Camino Real, Fronteras, Monterey, Florida Sensation, and Sweet Charlie. Experiments were conducted in a randomized complete block design in a commercial tabletop greenhouse in eastern North Carolina over two growing seasons (2022–23 and 2023–24). Our results showed that Florida cultivars Brilliance and Florida Sensation produced more consistently yields in winter compared with long-day cultivars Albion and Monterey and produced similar yields over the entire season. ‘Brilliance’ especially showed high fruit firmness across both years, and high sweetness in one of the two years. Additionally, the short-day cultivar Fronteras showed high yields in early spring and could serve as a late-season crop for direct-to-consumer producers. Our study showed that ‘Brilliance’ and ‘Florida Sensation’ could be alternatives to ‘Albion’, and that ‘Monterey’ can be used to produce a winter crop in a soilless tabletop production system in the Southeast.

Prediction of Carbon Dioxide Concentrations in Strawberry Greenhouse by Using Time Series Models

Carbon dioxide (CO2) concentrations play an important role in plant production, as they have a direct impact on both plant growth and yield. Therefore, the objectives of this study were to predict CO2 concentrations in the greenhouse by applying time series models using five datasets. To estimate the CO2 concentrations, this study was conducted over a four-month period from 1 December 2023 to 31 March 2024, in a strawberry-cultivating greenhouse. Fifteen sensors (MCH-383SD, Lutron, Taiwan) were installed inside the greenhouse to measure CO2 concentration at 1-min intervals. Finally, the dataset was transformed into intervals of 1, 5, 10, 30, and 60 min. The time-series data were analyzed using the autoregressive integrated moving average (ARIMA) and the Prophet Forecasting Model (PFM), with performance assessed through root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R2). The evaluation indicated that the best model performance was achieved with data collected at 1-min intervals, while model performance declined with longer intervals, with the lowest performance observed at 60-min intervals. Specifically, the ARIMA model outperformed across all data collection intervals while comparing with the PFM. The ARIMA model, with data collected at 1-min intervals, achieved an R2 of 0.928, RMSE of 7.359, and MAE of 2.832. However, both ARIMA and PFM exhibited poorer performances as the interval of data collection increased, with the lowest performance at 60-min intervals where ARIMA had an R2 of 0.762, RMSE of 19.469, and MAE of 11.48. This research underscores the importance of frequent data collection for precise environmental control in greenhouse agriculture, emphasizing the critical role of short-interval data collection for accurate predictive modeling.

First Report of Fusarium oxysporum f. sp. fragariae Causing Fusarium Wilt on Strawberry (Fragaria × ananassa) in Saudi Arabia.

Recently, Saudi growers have expanded their production of organic, soilless-grown strawberries (Fragaria × ananassa Duch.), but their production shows many difficulties associated with disease susceptibility. In October 2021, 45% of strawberry plants cv. "Festival" organically cultivated in Dammam city, Saudi Arabia (26°31'34.5"N 50°00'51.0"E) showed wilting symptoms. Typical symptoms were yellowing, rapid wilting, death of older leaves, stunting, and decreased roots. Vascular bundle necrosis and crown and root rot were also observed; plants eventually collapsed and died. Twenty symptomatic strawberry plants were sampled to isolate the pathogen. Pieces (4 × 4 mm) of the symptomatic tissues from crowns and roots were sanitized with 1% NaOCl (90 s), submerged in 70% alcohol (20 s), rinsed with sterile water (2x 30 s), placed on potato dextrose agar (PDA; Scharlau Chemie, Spain) and incubated at 25°C for 6 days. Next, we prepared single-spore cultures on PDA and synthetic nutrient-poor agar (SNA). On PDA media, pure cultures produced abundant aerial mycelium, with light pink or purple pigmentation in the medium after incubation at 25°C for 7 days. On SNA media, aerial microconidia were abundant cylindrical to ellipsoid hyaline with zero to one septate (3.8 - 5.9 × 1.3 - 2.5 μm, n = 50). Macroconidia were few, hyaline and falcate, with slightly curved apexes and 2 to 4 septate (18.9 - 27.5 × 3.3 - 4.6 μm, n = 50). Chlamydospores were roundish and terminal or intercalary. As Leslie and Summerell (2006) described, such morphological characteristics are typical of F. oxysporum. The isolates' identities were established by extracting DNA using the DNeasy Plant Mini kit (QIAGEN, Hilden, Germany). This was followed by amplification and sequencing of the internal transcribed spacer (ITS) (White et al., 1990), elongation factor 1-α (TEF1-α) (O'Donnell et al., 1998), and the ribosomal RNA intergenic spacer (IGS) (Canizares et al., 2015). The ITS, TEF1-α, and IGS sequences of an isolate Fof-10 were submitted to GenBank (PP564462, PP703242, and PP784894, respectively). BLAST analysis confirmed 99.71 and 100% identities to the ITS, TEF-1α, and IGS sequences of F. oxysporum (KU931552.1, OR640020.1, and FJ985519.1), respectively. All isolates tested were confirmed at the forma specialis fragariae, level using the specific primers FofraF/FofraR (Suga et al. 2013). The ∼239 bp amplicon was sequenced and submitted to GenBank (PP703243). Two-month-old healthy strawberry plants of cultivars "Festival," "Marquis," and "Monterey" were inoculated by dipping the roots in the spore suspension (107 conidia ml-1) for 15 min (Henry et al. 2017). There were five replicates for each cultivar. Plants dipped in water were used as a control treatment. The plants were transplanted in sterilized soil and placed in a greenhouse at 30/26°C (day/night). Within 4 to 6 weeks, inoculated plants showed severe wilting and discoloration of the internal crown tissue, while control plants were symptomless. The pathogen was re-isolated from the discolored vascular tissue onto PDA and identified morphologically and molecularly as the original one, thus fulfilling Koch's postulates. The test was repeated twice. This report confirms F. oxysporum f. sp. fragariae as a causal agent of Fusarium wilt of strawberries in Saudi Arabia. This pathogen was previously reported to cause the Fusarium wilt of strawberries in California (Dilla-Ermita et al., 2023). This disease has been observed in several hydroponic strawberry greenhouses in Saudi Arabia, with incidence ranging from 25% to 45% across multiple locations. Given this, proper strategies are needed to manage this disease and to be compatible with organic farming.

Impact of CO2 Enrichment on Growth, Yield and Fruit Quality of F1 Hybrid Strawberry Grown under Controlled Greenhouse Condition

Carbon dioxide enrichment inside a greenhouse is a sustainable approach to increasing crop production worldwide. Recently, the F1 hybrid strawberry became an alternative to runner-propagated cultivation as an innovative method to shorten the production period and increase strawberry production. This work aims to present CO2 enrichment as a sustainable tool that improves the yield in a controlled greenhouse and addresses the efficiency of three F1 hybrid strawberry varieties grown under Saudi Arabian conditions. A greenhouse experiment was conducted at the National Research and Development Center for Sustainable Agriculture (Estidamah), KSA, to study the impact of two CO2 levels (400 ppm (“ambient”) and 600 ppm (“enrichment”)) on the growth, photosynthesis traits, fruit yield and fruit quality of three F1 hybrid strawberry varieties grown under soilless culture conditions. The results show that CO2 enrichment significantly improved the phenotyping of strawberry growth traits at 60 days post-transplanting. The physiological response of the varieties to CO2 enrichment reveals a significant increase in the photosynthetic rate (129.7%) and intercellular CO2 (43.7%) in the leaves of strawberry exposed to CO2 enrichment rather than in ambient conditions, combined with a significant increase in the number of fruits per plant (27.5%) and total fruit yield (42.2%). A similar pattern was observed with varieties D and S in terms of fruit number, length and diameter. However, CO2 at 600 ppm promoted total soluble solid accumulation and vitamin C for the tested varieties. In contrast, CO2 enrichment significantly decreased nitrogen, phosphorus, potassium and magnesium accumulation in the leaves of the exposed plants in comparison to 400 ppm of CO2. These results suggest that increasing CO2 enrichment could contribute to an increase in strawberry yield and nutritional value and demonstrate that understanding the response of each variety to CO2 enrichment is important to support selecting suitable greenhouse strawberry varieties to improve crop yield.

Occurrence pattern of diseases and pests in strawberry greenhouse during harvest period

Occurrence pattern of diseases and pests in strawberry greenhouse during harvest period

The recent occurrence pattern of diseases and pests in strawberry greenhouse of Chungnam province, South Korea, during nursery period

The recent occurrence pattern of diseases and pests in strawberry greenhouse of Chungnam province, South Korea, during nursery period

Enhancing greenhouse strawberry irrigation: integrating IoT technologies and low-cost moisture sensors in substrate

The integration of Internet of Things (IoT) technologies, particularly sensor-based systems, is revolutionizing agriculture, including strawberry cultivation in greenhouses. Furthermore, the use of wireless communication technologies, alongside efficient data storage and visualization platforms, can enhance monitoring and decision-making capabilities. This study aimed to calibrate and verify the real-time operation of the low-cost SKU SEN0193 V2.0 sensor and the SHT20 in strawberry cultivation substrate, evaluating IoT technologies for data transmission, including LoRa, InfluxDB for storage, and Grafana for visualization and monitoring. The adaptability and accuracy of the SHT20 and SKU SEN0193 V2.0 sensors were tested in laboratory and greenhouse strawberry crops. Water retention curves in the substrate were determined using the Haines Funnel, while recording sensor measurements simultaneously for calibration. For real-time monitoring, sensors were placed in two slabs with strawberry plants in a greenhouse. InfluxDB stored the data, and Grafana visualized it. While the SHT20 sensor showed limited suitability for substrates due to its lack of response to moisture variations, SKU SEN0193 V2.0 produced excellent results, detecting changes in moisture content in both laboratory and greenhouse tests. Sensor-specific calibration for greenhouse slabs is crucial. The utilization of data storage and visualization tools like InfluxDB and Grafana facilitated real-time data manipulation, demonstrating their potential for enhancing irrigation management in greenhouse strawberry production.

Nutrient Dynamics and Resource-Use Efficiency in Greenhouse Strawberries: Effects of Control Variables in Closed-Loop Hydroponics

The importance of implementing recirculating drainage for greenhouse strawberries is often overlooked because of the low electrical conductivity (EC) of drainage and transpiration despite the large area of cultivation in Korea. In this study, we analyzed the growth of strawberry crops and their water and individual nutrient use efficiency when using closed-loop hydroponics in greenhouses. The study consisted of two parts: Experiment (Exp) 1 and Exp 2, each of which employed a different closed-loop hydroponic control method. In Exp 1, the system was controlled solely based on the EC of the drainage mixed with raw water. In Exp 2, the nutrient solution (NS) was corrected according to the ion concentrations in the drainage, with correction intervals of 2 weeks, 4 weeks, and no correction, while the control treatment was open-loop. In Exp 1, a prolonged increase in drainage EC resulted in an imbalance in NS ion composition and reduced fruit yield. In Exp 2, the NS composition was stabilized through periodic nutrient correction, and the fruit yield of the closed-loop treatments did not differ from the open-loop treatment. However, the closed-loop with 2- and 4-week correction in Exp 2 showed 94% and 88% higher nutrient use efficiency (NUE), respectively, than an open-loop system. Among the closed-loop treatments, the 2- and 4-week correction intervals had 36% and 32% higher NUE than the no-correction treatment. Furthermore, the 2-week correction interval showed a 3% improvement in NUE compared to the 4-week interval. These findings highlight the importance of considering a shorter ion correction interval for optimal NUE and normal plant growth in recirculating hydroponic systems of strawberry cultivation.

Screening of optimal cleaning methods to reduce microplastic residues on strawberry surfaces: Characterization of microplastics in strawberry wash water

Microplastics are widespread in facility strawberry greenhouses and can be deposited on the surface of strawberries through air currents. Investigating effective cleaning methods represents a viable strategy to reduce human ingestion of MPs. Therefore, different cleaning methods were compared: ultrasonic cleaning for 30 min, deionized water rinsing once, deionized water immersion for 30 min, and fruit immersion in washing salt for 30 min. The MPs in strawberry washing water were analyzed and compared using laser direct infrared imaging to investigate their characteristics and the optimal reduction of MPs on the surface of strawberries. The quality of the cleaning results was in the following order: water immersion > washing salt immersion > water rinsing > ultrasound. Water immersion was 1.3–2 times more effective in removing microplastics than other treatments. Furthermore, 21 polymer types were detected in the samples. Most MPs were less than 50 µm in size. The main polymers in this size range were polyamide, chlorinated polyethylene, and polyethylene terephthalate, and they mainly existed as fragments, fibers, and beads. This study provides a valuable reference for reducing human intake of microplastics through fresh fruits and vegetables.

Increasing Cyetpyrafen Spray Volume and Ozone Spray Improves the Control Effects against Two-Spotted Spider Mite (Tetranychus urticae) in Strawberries.

The two-spotted spider mite (Tetranychus urticae) is a constant threat to greenhouse strawberry production. The application of synthetic acaricides is the main method of controlling T. urticae. However, resistance development to traditional acaricides reduces their efficacy and eventually leads to control failure. It is important for strawberry growers to look for new acaricides and application technologies that can limit the harmfulness of T. urticae in environmentally friendly ways. In the current study, laboratory toxicity tests and field trials were performed to screen high-efficiency acaricides, and then application technologies were improved to enhance the management of T. urticae. In the laboratory toxicity tests, the results showed that the LC50 (median lethal concentration) value of cyetpyrafen, cyenopyrafen, cyflumetofen, bifenazate, abamectin, azocyclotin, pyridaben, spirodiclofen, and etoxazole against adult T. urticae was 0.226, 0.240, 0.415, 3.583, 5.531, 25.58, 39.69, 140.3, and 267.7 mg/L, respectively. In addition, the LC50 value of the nine acaricides against eggs of T. urticae was 0.082, 0.097, 0.931, 18.56, 25.52, 45.61, 36.32, 1.954, and 0.040 mg/L, respectively. The field trial results showed that the best control effect was obtained in cyetpyrafen at 300 mL/ha treatment. Cyetpyrafen was chosen for further application technology tests. In the spray volume tests, the results showed that increasing the spray volume from 900 to 1050 L/ha significantly improved the control of T. urticae. In addition, the results from the spray instrument tests demonstrated that the control effects on T. urticae in the ozone spray treatments were significantly higher than those of the conventional and electrostatic sprays 1 and 3 days after treatment (DAT). Therefore, this study suggested that cyetpyrafen effectively controlled T. urticae both in the laboratory tests and in the field trials. Increasing the spray volume and application of ozone spray significantly improved T. urticae management.

Energy- and yield-based performance evaluation of a phase change material–integrated single-span double-layered with a thermal screen greenhouse

Greenhouse technology emerged to ensure the optimum yield of the host crop —a prerequisite to achieving Sustainable Development Goals 7 and 2. To achieve this, supplemental energy is needed under extreme weather conditions at about half the operational cost. Researchers have focused and succeeded in reducing the energy demand using numerical methods with little focus on the impact of these methods on crop yield. A novel greenhouse system—phase change material–integrated single-span double-layered strawberry greenhouse with a thermal screen—is introduced herein. Furthermore, how the energy management method affects the yield of the host crop is explored. Moreover, the energy-saving potential and yield enhancement achieved by integrating PCMs and other passive thermal-management systems in a specific agricultural setting is investigated. TRNSYS 18 software is used to evaluate the effect of three passive variables on two performance indices. The passive variables are location: Daegu (DG), Seoul, and Jeju Island (JE); orientation: 90° (E-W), 45° (NE-SW), and 0° (N-S); and PCM type: “No-fill”, water, and Paraffin (ParC13–C24). The effect of thermal screen control was also studied on the localized optium configuration. Finally, economic analysis was conducted to ascertain the most sustainable configuration. The performance indices are the heating demand and strawberry yield. The results show that the location, orientation, and PCM usage inside the greenhouse greatly affect the greenhouse’s heating demand and crop yield. The configuration selected must be in such a way that the indoor nighttime temperature does not exceed 2 °C above the minimum nighttime optimum value of the host crop.

Integration of the Generalist Predator Nabis americoferus (Hemiptera: Nabidae) in a Greenhouse Strawberry Biocontrol Program with Phytoseiid Predatory Mites and the Entomopathogenic Fungus Beauveria bassiana.

In strawberry production, western flower thrips (WFT) and two-spotted spider mites (TSSM) inflict feeding damage and reduce the yield. Biological control for these pests often includes phytoseiid predatory mites and entomopathogenic fungi. The hemipteran family Nabidae have been reported as prominent predators in open-field strawberry. Nabis americoferus Carayon is a new biocontrol agent developed in Canada. This study examined if this species was a good candidate for integration with biological control for greenhouse strawberry production. The laboratory trials showed that Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot were compatible with N. americoferus, especially when alternative food was available. In contrast, the nabid was not compatible with the Beauveria bassiana (Balsamo) GHA strain. A greenhouse cage study was conducted to determine if it was beneficial to add N. americoferus to the phytoseiid-mites-based biological control program for WFT and TSSM in greenhouse strawberry. The release of N. americoferus on a banker plant together with the placement of sachets of Neoseiulus cucumeris (Oudemans) and Neoseiulus californicus (McGregor) was beneficial, not only potentially reducing the number of sachet applications, but also providing better pest control than phytoseiid mites alone. Neither the phytoseiids nor the N. americoferus numbers were significantly affected by the presence of each other.

LED supplementary strategy based on hourly light integral for improving the yield and quality of greenhouse strawberries

LED supplementary strategy based on hourly light integral for improving the yield and quality of greenhouse strawberries

An Overview of Recent Advances in Greenhouse Strawberry Cultivation Using Deep Learning Techniques: A Review for Strawberry Practitioners

Strawberry (Fragaria × ananassa Duch.) has been widely accepted as the “Queen of Fruits”. It has been identified as having high levels of vitamin C and antioxidants that are beneficial for maintaining cardiovascular health and maintaining blood sugar levels. The implementation of advanced techniques like precision agriculture (PA) is crucial for enhancing production compared to conventional farming methods. In recent years, the successful application of deep learning models was represented by convolutional neural networks (CNNs) in a variety of disciplines of computer vision (CV). Due to the dearth of a comprehensive and detailed discussion on the application of deep learning to strawberry cultivation, a particular review of recent technologies is needed. This paper provides an overview of recent advancements in strawberry cultivation utilizing Deep Learning (DL) techniques. It provides a comprehensive understanding of the most up-to-date techniques and methodologies used in this field by examining recent research. It also discusses the recent advanced variants of the DL model, along with a fundamental overview of CNN architecture. In addition, techniques for fine-tuning DL models have been covered. Besides, various strawberry-planting-related datasets were examined in the literature, and the limitations of using research models for real-time research have been discussed.

Detection of deformed wing virus in the greenhouse for possible horizontal transmission of virus in honey bee colony

AbstractThe honey bee Apis mellifera L. is a crucial insect in the agricultural industry and natural ecosystem by being a major pollinator. Nevertheless, honey bee population has been recently facing a decline. Among the several factors responsible for this decline, deformed wing virus (DWV) is considered a primary cause that negatively affects honey bee health. DWV is a cosmopolitan honey bee pathogen and causes morphological disadvantages in individual honey bees and colony collapse. Regarding the horizontal transmission of DWV, in addition to Varroa destructor, a well‐known major vector of DWV, flowers have recently been implied as a transmission route. Therefore, in this study, we detected DWV from various substances, including flowers, honey bee feces, pupa, larva, nurse bee, surface of nurse bee, pollen collected by forager bee, and forager bee samples in four strawberry greenhouses, which could suggest the potential for the horizontal transmission of DWV in the semi‐field condition. We also detected DWV in pollen collected by DWV‐negative forager bees, implying that flowers can serve as a potential source of virus infection. These findings suggest that the surrounding environment such as shared floral sources affects the spread of DWV.

Eco-friendly strategy for CO2 enrichment performance in commercial greenhouses based on the CO2 spatial distribution and photosynthesis

CO2 enrichment is an essential environmental control technology due to its significantly enhancing effect on crop production capacity. Despite being a key energy consumer in protected agriculture (i.e. greenhouse systems), CO2 enrichment remains at a low energy use efficiency level, highlighting the need for developing more energy-efficiency strategies for CO2 enrichment. Therefore, this study employed the computational fluid dynamics (CFD) simulation method to replicate the CO2 diffusion process resulting from CO2 enrichment in three commercial strawberry greenhouses with varying geometric characteristics. Based on the CFD-simulated CO2 concentration distributions, the leaf photosynthetic rate was calculated using a mathematical model group. The CO2 enrichment efficiency was then analysed by calculating the ratio of increased photosynthesis across the cultivation area to the amount of energy (in CO2 equivalent) used. The efficiency peaked when the average CO2 concentration was approximately 500 μmol mol−1, thereby providing guidance for determining the target concentration of CO2 enrichment in production. Although this study is limited as the CFD simulation only considered a typical short-period CO2 enrichment event, future research will provide a broader analysis by considering changes throughout the day.

Combined nighttime ultraviolet B irradiation and phytoseiid mite application provide optimal control of the spider mite Tetranychus urticae on greenhouse strawberry plants.

Tetranychus urticae is a hard-to-control pest of greenhouse strawberry production. Nighttime ultraviolet B (UV-B) radiation using light reflection sheets (LRS) has been applied as a physical method to control T. urticae through direct ovicidal effects (the UV method). However, because strawberry leaves grow more densely, UV-B radiation fails to reach the lower leaf surfaces inhabited by spider mites; therefore, a complementary method is required. We propose the supplemental application of phytoseiid mites in greenhouse strawberry production. We evaluated the control effects of UV-B irradiation, phytoseiid mite application and their combined use. The effects of UV-B irradiation on the degree of overlap relative to the independent distributions (ω) between predators and prey were also analyzed. The UV method alone maintained low T. urticae density levels from November to February; however, mite populations increased from March onward. Phytoseiid mite application in January and February without UV-B irradiation resulted in a temporary increase in spider mites in March and/or April. By contrast, combined application of the UV method and phytoseiid mites had a greater control effect during the strawberry growing season. The ω values were higher for the UV method compared with no UV-B irradiation, suggesting that UV-B irradiation increased phytoseiid mite foraging rates. The release of phytoseiid mites compensated for the shortcomings of the UV method, and UV-B irradiation promoted predation by phytoseiid mites by increasing the behavioral numerical response. Consequently, combined application of UV-B irradiation and phytoseiid mites is optimal for T. urticae control in greenhouse strawberry production. © 2023 Society of Chemical Industry.

Automatic pest identification system in the greenhouse based on deep learning and machine vision.

Monitoring and understanding pest population dynamics is essential to greenhouse management for effectively preventing infestations and crop diseases. Image-based pest recognition approaches demonstrate the potential for real-time pest monitoring. However, the pest detection models are challenged by the tiny pest scale and complex image background. Therefore, high-quality image datasets and reliable pest detection models are required. In this study, we developed a trapping system with yellow sticky paper and LED light for automatic pest image collection, and proposed an improved YOLOv5 model with copy-pasting data augmentation for pest recognition. We evaluated the system in cherry tomato and strawberry greenhouses during 40 days of continuous monitoring. Six diverse pests, including tobacco whiteflies, leaf miners, aphids, fruit flies, thrips, and houseflies, are observed in the experiment. The results indicated that the proposed improved YOLOv5 model obtained an average recognition accuracy of 96% and demonstrated superiority in identification of nearby pests over the original YOLOv5 model. Furthermore, the two greenhouses show different pest numbers and populations dynamics, where the number of pests in the cherry tomato greenhouse was approximately 1.7 times that in the strawberry greenhouse. The developed time-series pest-monitoring system could provide insights for pest control and further applied to other greenhouses.

First worldwide report of Exserohilum rostratum causing leaf spot on strawberry (Fragaria × ananassa Duch.).

During April 2022, leaf spot was observed on strawberry (Fragaria × ananassa Duch.) with a disease incidence of approximately 45% among 100 plants. Strawberry was cultivated in a nursery at Huzhou University (30.87゜N, 120.13゜E), Zhejiang Province, China. In the strawberry greenhouse, the average temperature was 15-18 degrees, 40%-60% humidity. Early symptoms appeared as dark brown or black spotted necrotic lesions, which expanded from 2 to 6 mm in diameter. Dark brown spots with yellow halos occupied half of the leaf area and eventually developed leaf blight with large yellow halos. To isolate the causal agent, 0.5 cm x 0.5 cm fragments were cut from three symptomatic leaves, and were surface sterilized with 75% ethanol for 30 s and then rinsed three times with sterilized water. The airdried leaf fragments were placed on PDA with 50 μg/ml ampicillin and incubated in the dark at 25℃ for two days. Isolates were obtained by transferring hyphal plugs of 1 mm in diameter onto PDA. The colony morphology was circular and dark brown on the upperside and black on the underside, with cottony mycelium and an large amount of gray aerial mycelium. Conidia were large, light olive-brown to dark olive-brown and light olive-black and septate. The typical conidia were oval or rod-shaped, rarely curved, and dark septa defined the basal and apical cells. In the two typical forms of conidia, the average size of oval conidia was approximately 18.77 × 54.92 μm (11.99 to 26.97 × 35.13 to 74.59 μm, n = 20), and the average size of the rod-shaped conidia was approximately 14.80 × 103.24 μm (11.24 to 24.64 × 73.11 to 131.51 μm, n = 20). The morphological characteristics matched well with previous descriptions of Exserohilum rostratum (Sharma et al. 2014; Liu et al. 2021). The identity of C1-L and C1-S from symptomatic tissues was confirmed by means of multi-locus gene sequencing. Genomic DNA was extracted from the mycelium using the CTAB (cetyltrimethylammonium bromide) method (Griffith & Shaw 1998). Molecular identification was conducted by sequencing the internal transcribed spacer (ITS) rDNA region, partial glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, partial actin (ACT) gene, and partial beta-tubulin 2 (TUB2), using the primers ITS1/ITS4 (White et al. 1990), GDF/GDR (Templeton et al. 1992), ACT512F/ACT783R (Carbone and Kohn 1999), T1 (O'Donnell and Cigelnik 1997) and Bt2b (Glass and Donaldson, 1995). The obtained sequences of C1-L and C1-S were the same. Moreover, the sequences have been deposited in GenBank under accession numbers ON982516 (ITS), ON996915 (GAPDH), ON996916 (ACT), and ON996917 (TUB2). The results of Basic Local Alignment Search Tool (BLAST) analysis revealed that the ITS, GAPDH, and ACT had 100% identity with the sequences of E. rostratum (GenBank Accession No. LT837834, LT883550, and LT837672, respectively), the TUB2 had 99.61% similarity with BLAST sequences of E. rostratum (LT899391). These morphological characteristics and molecular analyses allowed the identification of the pathogen as E. rostratum. Koch's postulates were performed with five healthy detached strawberry leaves with three inoculations per leaf of the 'Akihime' strawberry variety. Surface-sterilized leaves were wounded with an aseptic needle, and inoculated with 2 mm diameter mycelial plugs from 5-day-old cultures of E. rostratum. Control leaves were also wounded with the aseptic needle, and inoculated with a sterile PDA agar plug. The leaves were incubated at 25℃ in Petri plates with petioles wrapped in moist sterile cotton. The diseased symptoms included black spots on the epidermis of the wounded leaves within 5, 10, and 20 days after inoculation. Mock-inoculated controls remained asymptomatic, and three biological repetitions were conducted. The fungus reisolated from the diseased leaves was confirmed as E. rostratum by sequencing. Abundant reports have shown that E. rostratum can infect many economically important crops such as maize, rice, and pineapple (Sun et al. 2021; Kabore et al. 2022; Luo et al. 2012). To the best of our knowledge, this is the first report of E. rostratum on strawberry in China and worldwide.

Pest Insect Species and Their Population Fluctuation in Greenhouse Strawberry Cultivation

Türkiye, çilek üretiminde dünyanın önde gelen ülkelerinden biridir. Antalya ili Türkiye çilek üretiminde üçüncü, örtüaltı çilek üretiminde ise ikinci sırada yer almaktadır. Örtüaltı çilek üretiminde sorun olan zararlı böcek türlerini belirlemek amacıyla ele alınan bu çalışma, Antalya’da 2019-2020 ve 2020-2021 üretim sezonunda yürütülmüştür. Çalışmada, örtüaltı topraksız üretim serasında haftalık olarak bitki örneklemeleri yapılmış ve zararlı takibinde yapışkan tuzaklardan yararlanılmıştır. Çalışma sonucunda örtüaltı çilek üretiminde Crysodeixis chalcites (Esper, 1789), Autographa gamma (Linnaeus, 1758), Spodoptera littoralis (Boisduval, 1833) (Lepidoptera, Noctuidae), Aulacorthum solani (Kaltenbach, 1843) (Hemiptera: Aphididae), Frankliniella occidentalis (Pergande, 1895) ve Thrips tabaci (Lindeman 1889) (Thysanoptera: Thripidae)’nin öne çıkan türler olduğu tespit edilmiştir. Çalışmada C. chalcites, en fazla 0.08 larva/bitki, A. gamma ve S. littoralis ise birlikte 0.08 larva/bitki yoğunluğunda belirlenmiştir. Aulacorthum solani yapışkan tuzaklarda en fazla 12, yaprakta ise 3.98 birey olarak tespit edilmiştir. Thrips türleri tuzakta en fazla 199 birey olarak belirlenmiş, yapraklarda ve çiçeklerde ise önemli bir yoğunluk oluşturmadığı ortaya konulmuştur.