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Open-field-grown tomatoes in Saudi Arabia are stressed by poor soil fertility because of the low organic matter content, low nutrient availability, and high pH. Thus, high chemical fertilizer inputs are crucial for commercial production; however, they cause economic loss as well as negatively affect environmental sustainability. The use of efficient organic fertilizers would be useful for developing more cost-effective, environmentally friendly, and sustainable agriculture. The current study evaluated the impact of Black soldier fly (Hermetia illucens L.) frass (BSFF) fertilizer applications as organic fertilizer on postharvest fruit quality and shelf life of open-field-grown F1 hybrid ‘Sinag Tala’ tomatoes compared with those grown under control treatment (received recommended doses of chemical fertilizers for tomato production under open field conditions). The experiment was conducted using a randomized complete block design with four replicates. The results showed that the application of BSFF fertilizer, especially at the higher rate (5 ton/ha; BSFF3), improved the overall quality of tomato fruit. The BSFF fertilizer treatments reduced weight loss, maintained higher firmness, antioxidants [vitamin C, total phenol content (TPC) and total flavinoid (TFC)], total soluble solids (TSS), and titratable acidity (TA) contents, and lowered the TSS/TA ratio of fruits during shelf life compared with those of the control. The decay incidence was only detected after 9 days of shelf life and was significantly lower in all the BSFF fertilizer treatments (range, 8.40%-12.05%) than in the control (15.9%). In addition, BSFF fertilizer treatments reduced both disease incidence and severity of gray mold following pathogen inoculation during shelf life compared with those of the control. These results might be attributable to the higher antioxidants content (vitamin C, TPC, and TFC) and higher polyphenol oxidase activity in BSFF-fertilized tomatoes. In conclusion, BSFF fertilizer could be used as a potential eco-friendly alternative to chemical fertilizers to improve tomato fruit quality during shelf life.

Abstract Background The reduced rate of potato production may occur under different conditions such as field, transit, storage, and marketing. Potato cultivation is frequently affected by various pathogens, among which Pectobacterium carotovorum subsp. carotovorum is a notorious bacterial pathogen responsible for causing bacterial soft rot disease. This pathogen poses a significant threat to potato production worldwide, resulting in substantial economic losses and food security concerns. This study aimed to investigate the effectiveness of three bacterial bioagents, namely Brevundimonas bullata, Bacillus siamensis, and Bacillus velezensis, against P. carotovorum subsp. carotovorum, a notorious bacterium responsible for causing potato tuber soft rot disease. Results Fifteen isolates were isolated from rhizosphere of potato plants. Out of 15 isolates, 3 isolates, No. 1, 11, and 12, showed highly antagonistic property to control the growth of P. carotovorum subsp. carotovorum in vitro. They were identified as B. bullata, B. velezensis, and B. siamensis, by using 16S rRNA nucleotide sequence analysis. Results from these experiments revealed that three bioagents exhibited notable inhibitory effects on the growth of the pathogenic bacterium. However, B. velezensis stood out as the most effective inhibitor among the tested bioagents, showcasing the highest level of bacteriostatic activity (2.6 cm). The findings from the in vitro experiments provided promising insights into the potential of these bacterial bioagents as natural antagonists against potato tuber soft rot disease. Building upon these promising results, the study recommended the utilization of all tested bioagents for controlling soft rot disease in potato tubers, especially during storage conditions where the risk of bacterial proliferation is heightened. Treatment with B. bullata, B. siamensis, and B. velezensis demonstrates varying degrees of efficacy in controlling the progression of soft rot disease. Notably, B. velezensis shows promising results with relatively low disease severity scores across all time points compared to the other treatments. B. velezensis demonstrates the lowest disease severity percentage at 7.00% compared to the other treatments. Conclusions The study underscores the significant potential of B. bullata, B. siamensis, and B. velezensis as effective biological control agents against potato tuber soft rot disease. By targeting the causative agent directly, these bioagents offer a promising avenue for mitigating the detrimental impact of soft rot disease on potato production, thereby contributing to improved crop yield and quality.

Abstract Background Purple blotch disease is a devastating disease, resulting in significant yield losses in onion. Application of synthetic fungicides is a rapid approach for the control of this disease, but extensive use of synthetic fungicides results in resistance development in pathogen. Thus, it is mandatory to explore alternative approaches to overcome the fungicide resistance challenges. The present study focused on a sustainable biocontrolling approach by using biocontrol yeast. The objective was to develop a management strategy that offers an environmentally acceptable alternative to commonly used fungicides. Results A total of six pathogenic isolates were obtained from the infected onion leaves, out of all tested isolates, OP-4 recorded as highly virulent with disease incidence (75.2%). Filobasidium wieringae and Pichia kluyveri drastically reduced the in vitro mycelial growth of Alternaria porri (14 and 21 mm, respectively). In the greenhouse experiment, plant inoculated with P. kluyveri suspension was the most effective, resulting in considerable reduction (77.1%) in disease severity, before two days of pathogen inoculation. However, F. wieringae showed a considerable reduction (84.5%) in disease severity when applied in combination with P. kluyveri two days post-inoculation. Conclusions These findings highlighted the strong biocontrol potential of P. kluyveri and F. wieringae in managing the purple blotch disease of onion and can reduce the reliance on synthetic fungicides. Further research and field trials should be conducted to optimize the application methods and evaluate the long-term effectiveness of these bioagents.

Abstract Background Leveillula taurica is an obligate pathogen that causes powdery mildew on chili pepper (Capsicum annuum L.) which is considered one of the most serious diseases for the crop. Results Leveillula taurica was isolated from infected pepper plants in Assiut Governorate, Egypt. Pathogenicity test was performed, and it was found that the pathogen can cause the symptoms of powdery mildew on the pepper plant. Under greenhouse conditions, treatment with Bacillus thuringiensis MW740161.1, Pseudomonas fluorescens, and Bacillus subtilis cultures resulted in a significant reduction in conidial germination of the pathogen (69.07, 29.55, and 19.58%, respectively). Spraying chili pepper plants with the microorganisms effectively reduced the powdery mildew's disease severity. Also, treatment with the bacterial strains resulted in a significant (P 0.05%) increase in the yield of chili pepper. Based on the findings, it appears that the use of B. thuringiensis, as foliar spraying, significantly induced resistance of chili pepper plants against L. taurica and stimulated many biochemical functions in the plant. Also, it increased the crop yield compared to all other treatments. Conclusions This study recommends B. thuringiensis as a viable alternative to harmful pesticides, and it is feasible to formulate an appropriate fungicide for the sustainable green production of chili peppers. The B. thuringiensis can increase the resistance of chili pepper plant to L. taurica the causal pathogen of powdery mildew.

AbstractDue to the increasing need for food security across the world, it has become urgent to develop a combination of different agricultural inputs that can enhance higher crop productivity under plant growth limiting environment. Thus, the effects of a cellulose decomposing bacterium (Geobacillus stearothermophilus SSK-2018), humic acid, and wheat straw were evaluated on the growth of Cucurbita pepo L. (squash) under an arid land condition during a two-year (2020 and 2021) field trials. Laboratory analysis revealed that G. stearothermophilus SSK-2018 was a gram-positive bacterium capable of promoting plant growth by producing indole-3-acetic acid as well as enzymatic activities including cellulase, amylase, protease, gelatinase, and phosphatase. Consequently, the inoculation of SSK-2018 significantly increased (P ≤ 0.05) squash’s fresh stem, leaf, and root weights by 14.70%, 18.63% and 11.13%, respectively, compared to the uninoculated control. Humic acid significantly (P ≤ 0.05) increased fresh stem, leaf, and root weights by 78.78%, 62.5% and 63.74%, respectively, compared to the control. Wheat straw also significantly increased (P ≤ 0.05) fresh stem, leaf, and root weights by 52.68%, 30.32% and 42.30%, respectively, compared to the control. Furthermore, the combinations of the treatments, including humic acid and straw, SSK-2018 and straw, and humic acid, SSK-2018 and straw, significantly increased the growth of squash. Soil properties including bulk density, moisture content, and basic cations were also significantly (P ≤ 0.05) improved by humic acid, SSK-2018 and wheat straw. This study suggests that like NPK, bio-organic treatments including SSK-2018, humic acid and straw, can equally improve plant’s fresh stem, leaf, and root weights as well as soil’s bulk density, moisture content, and basic cations (K+, Ca2+, Na+, and Mg2+). Therefore, the present study recommends the continuous use of bio-organic amendments to achieve a sustainable improvement in plant growth and soil properties under arid land conditions. However, the continuous use of soil bio-organic amendments should be regularly monitored for potential increase in greenhouse gas emissions that may be at par with that of N fertilizers.

Abstract Background Bacterial wilt caused by Ralstonia solanacearum is considered one of the most important diseases that cause economic losses to many economic crops and spread in many regions around the world, especially in the subtropical tropics and some warm temperate regions of the world. In this study the aqueous plant extract of Rosemarinus officinalis and Pseudomonas fluorescens for their antagonistic activity against bacterial wilt in vitro, greenhouse and population of R, solanacearum in plants was study. Results Following intensive screening studies, aqueous plant extract of R. officinalis and P. fluorescens was selected to study their effectiveness against bacterial wilt of potato plants and their antimicrobial activity or induction of systemic resistance in plants. In greenhouse, all soil drenching treatments on potato plants significantly reduced disease incidence of potato bacterial wilt than infected control. R. officinalis, P. fluorescens mixture between plant extract and endophytic bacteria and streptomycin reduced profoundly the disease severity by 75.51, 65.0 77.9 and 81.00%, respectively, than the infected control (83.71%). The plant extract and microorganism significantly increased fresh and dry weight of potato plants (g) per plant compared to non-treated control plants. R. officinalis, P. fluorescens mixture between plant extract and endophytic bacterium and streptomycin increased fresh weight from 100.1 to 169.9 compared to infected control also increased dry weight from 68.4 in streptomycin to 170.4% in mixture of plant extract and endophytic bacterium. The populations of bacterial pathogen R. solanacearum were lowest in stem of potato plants treated with plant extracts than in inoculated control plants (50%). In general, the total phenols increased in both inoculated and non-inoculated potato plants. Conclusions Ralstonia officinalis and P. fluorescens showed a strong in vitro activity in relation growth limitation of R. solanacearum as well as limiting the development of bacterial wilt disease on potato plants under greenhouse conditions.

Abstract Background The present study aimed to examine the biocontrol efficacy of 28 yeast isolates against Aspergillus niger, the common pathogen of onion black mold disease. The antagonistic potential of yeast isolates against A. niger growth was investigated using a dual culture technique. Results Five yeast isolates, including 8 and 11, showed the highest inhibition effect on the mycelial growth of A. niger. Molecular analysis using 16S RNA identified strains 8 (AUN-AH14) and 11 (AUN-AH23) as Galactomyces geotrichum (JQ713185.1) and G. geotrichum (DQ849321.1), respectively. The culture filtrates of AUN-AH14 and AUN-AH23 at percentage concentrations of 20, 40, 60, and 80 were tested against the growth of A. niger. As a result, the lowest dry weight of the pathogen was obtained with culture filtrates of the two strains at concentrations of 60 and 80%.. Treatment of onion bulbs with formulation of antagonistic yeast isolates AUN-AH14 and AUN-AH23 and their corresponding cultural filtrates at 80% concentration significantly reduced the severity of black mold disease relative to the controls. Conclusions The most significant reduction in black mold severity was proved in yeast formulations of AUN-AH14 and AUN-AH23, followed by their cultural filtrates (CF-AUN-AH14 and CF-AUN-AH23). The shelf life of formulated yeast isolates began to gradually deteriorate after 5 months of storage at 4 °C.

Controlling early blight of tomatoes using endophytic bacteria is an eco-friendly and sustainable approach to manage this common fungal disease caused by Alternaria solani, Alternaria alternata, and Curvularia lunata. Endophytic bacteria are microorganisms that live inside plant tissues without causing harm and can help protect the host plant from pathogens. In this work, twenty endophytic bacterial isolates from tomato healthy plants were tested against pathogenic fungal isolates that caused early blight disease in vitro. Out of the 20 tested isolates, three (B4, B7, and B17) were considered effective isolates against the growth of fungal pathogens. The three isolates were recognized as Enterobacter cloacae HS-6 (B4), Pseudomonas gessardii HS-5 (B 7), and Pseudomonas mediterranea HS-4 (B17) using 16s-rDNA sequencing. Different concentrations of bacterial cultural diltrates at 20, 40, and 60% were tested for their antagonistic effects on the development of pathogenic fungi in vitro. The lowest dry weights of pathogenic isolates in all bacterial culture filtrates were discovered at 60%. In all culture filtrates, phenolic compounds showed the largest peak area. Under greenhouse conditions, the least disease severity of tomato early blight was found for E. cloacae and its culture filtrate compared to other treatments. Real-time PCR was used to examine the expression pattern of the defense response gene β-1.3 glucanase gene in infected tomato plants with pathogenic fungi (control) as well as its relations with efficient biocontrol agent (E. cloacae). The expression of the gene increased substantially and significantly after three days from the inoculation-infected plants with C. lunata and E. cloacae while it reached the maximum after five days from the inoculation with A. alternata, A. solani and E. cloacae. Our study concluded that the endophytic bacterial isolate E. cloacae can be considered a promising biocontrol agent for preventing tomato early blight.

IntroductionAlternaria solani is a challenging pathogen in the tomato crop globally. Chemical control is a rapid approach, but emerging fungicide resistance has become a severe threat. The present study investigates the use of culture filtrates (CFs) of three species of Trichoderma spp. to control this disease.MethodsHighly virulent A. solani strain and three Trichoderma fungal strains viz., T. harzianum (Accession No: MW590687), T. atroviride (Accession No: MW590689) and T. longibrachiatum (Accession No: MW590688) previously isolated by authors were used in this study. The efficacy of culture filtrates (CFs) to mitigate early blight disease were tested under greenhouse and field conditions, experiments were conducted in different seasons of 2020 using a tomato variety “doucen”.Results and discussionThe CFs of T. harzianum, T. longibrachiatum, and T. atroviride significantly inhibited the in vitro mycelial growth of A. solani (62.5%, 48.73%, and 57.82%, respectively, followed by control 100%). In the GC–MS analysis of Trichoderma CF volatile compounds viz., harzianic acid (61.86%) in T. harzianum, linoleic acid (70.02%) in T. atroviride, and hydroxymethylfurfural (68.08%) in the CFs of T. longibrachiatum, were abundantly present. Foliar application of CFs in the greenhouse considerably reduced the disease severity (%) in all treatments, viz., T. harzianum (18.03%), T. longibrachiatum (31.91%), and T. atroviride (23.33%), followed by infected control (86.91%), and positively affected the plant biomarkers. In the greenhouse, the plants treated with CFs demonstrated higher flavonoids after 6 days of inoculation, whereas phenolic compounds increased after 2 days. The CF-treated plants demonstrated higher antioxidant enzymes, i.e., phenylalanine ammonia-lyase (PAL) and peroxidase (POD), after 4 days, whereas polyphenol oxidase (PPO) was higher after 6 days of inoculation, followed by healthy and infected controls. In open field conditions, disease severity in CF-treated plants was reduced in both seasons as compared to naturally infected plants, whereas CF-treated plants exhibited a higher fruit yield than controls. The present results conclude that CFs can be a potential biocontrol candidate and a promising alternative to the early blight pathogen for sustainable production.

Abstract Background The red palm weevil (RPW), Rhynchophorus ferrugineus (Coleoptera: Curculionidae), overruns date palm ranches in most Oases of Saudi Arabia and causes massive economic losses. Integrated pest management (IPM) of the RPW by biocontrol agents of bacterial isolates was the primary aim of the present study. Results Thirty-seven bacterial isolates were isolated from the larvae of R. ferrugineus, which were collected from infested Phoenix dactylifera trees growing in different parts of Saudi Arabia. 16S rDNA sequencing showed that the isolated bacteria were: Serratia marcescens , Klebsiella pneumoniae and Bacillus thuringiensis. The potential of these isolates was tested against R. ferrugineus in the laboratory. The use of these three isolates showed significant mortality percentages against R. ferrugineus. The highest reduction in mortality was recorded at the concentration of 1 × 108 CFU/ml; B. thuringiensis isolate displayed the highest potency in mortal percentage rate (100%), 4 days post-treatment, followed by S. marcescens isolate after 5 days, and then K. pneumoniae isolate after 6 days. Conclusions These results suggest that the use of these bacterial isolates was very useful in in vitro experiments, and it may consider those bacterial strains of interest as a potential biocontrol agent of R. ferrugineus.

Abstract Background Early blight disease of tomato caused by pathogenic fungi Alternaria solani is the most significant and common disease throughout the world as well as in Kingdom of Saudi Arabia. The aim of this study was to isolate and identify native Trichoderma species from the Jeddah region in Saudi Arabia; evaluate their antagonistic potential against A. solani; and study their influence early blight disease severity in greenhouse and in open field. Results The present study focused to explore the biocontrolling potential of native Trichoderma spp. against A. solani strain to compare with a conventional fungicide. Out of 21, 3 Trichoderma isolates showed an antifungal activity and significantly inhibited the mycelial growth of pathogen that were identified as Trichoderma atroviride, T. harzianum and T. longibrachiatum by their ITS region sequence analysis. Strong in vitro mycelial growth suppression (70.66%) was also recorded at 400 ppm Mancozeb (90%WP®) fungicide. Further, these Trichoderma bioagents and fungicide were further evaluated in greenhouse (artificially inoculated) and in field on naturally infected tomato plants. In greenhouse, (13.74%) disease severity after T. harzianum treatment was recorded, followed by T. longibrachiatum (25.83%) and T. atroviride (21.67%). The disease severity after fungicide (50 mg/L; 10 ml per plant) application was (7.91%). Further, positive impact on the plant biomarkers was demonstrated by all selected Trichoderma isolates in greenhouse. Under natural infection in season I, the disease severity (%) after T. longibrachiatum, T. atroviride and T. harzianum treatments was 11.5, 13.26 and 16.81%, respectively, followed by control (32.12%), whereas 7.18% disease severity was recorded after fungicide application. Conclusions The results revealed that native Trichoderma of this region had potential to mitigate the early blight disease intensity in field.

Abstract Background Bacterial wilt of tomato (BWP) caused by Ralstonia solanacearum (Smith) is a very important disease. Biological control of this disease is a very important tool to protect the plant and environment from pollution of chemical control. Results Twenty isolates of genus, Pantoea were isolated from healthy tomato root. Out of 20 isolates, 2 strains, PHYTPO1 and PHYTPO2, showed highly antagonistic property to control the growth of R. solanacearum in vitro conditions. They were identified as P. agglomerans by using 16S rRNA nucleotide sequence analysis. The 2 isolates were selected to study their effect (as cell suspension or culture filtrate) on the bacterial wilt under greenhouse conditions. PHYTPO1 inhibited maximum growth reduction of R. solanacearum and formed 2.5 cm2 of inhibition zone, followed by 1.2 cm2 in PHYTOPO2 under in vitro conditions. Treating with both isolates of P. agglomerans was significantly reduced disease severity of tomato wilt disease. The disease severity was reduced to 74.1 when treated as cell suspension, while when treated as culture filtrate, it reduced the disease severity up to 69.4 than infected control. Conclusion The strains of Pantoea can be used as an ecofriendly method to control of the most economic pathogen of tomato under greenhouse conditions. Further study is needed to find an appropriate formulation and approving application of these bacteria under field conditions.

Abstract Background Green mold disease on citrus caused by Penicillium digitatum is the most serious and destructive disease. It is causing 90% of production losses during post-harvest handling. Results In this study, the activity of seven yeast isolates from lemons against P. digitatum, a fungal pathogen that causes the green mold disease in lemons, was isolated and examined. In vitro experiments showed that isolate three significantly reduced pathogen growths and were later identified as Schwanniomyces vanrijiae. In addition, 3% ethanolic extracts of propolis (EEP) caused a strong mycelial growth inhibition with inhibition halos of 1.4 cm. The use of S. vanrijiae treatments to protect lemon fruits from green mold has been reported (55%); however, reports describing the application of EEP are limited (40%). Thus, the effectiveness of the combination of S. vanrijiae and 3% EEP in an antagonistic mixture for protecting lemon fruits from P. digitatum was examined. EEP and S. vanrijiae treatments were applied alone and in combination in both in vitro and in vivo conditions. The combined application of 3% EEP + S. vanrijiae on lemon fruits significantly reduced the severity and incidence of green mold (80 and 93.7%, respectively) with much higher efficacy than either treatment alone. Lemon fruits treated with both S. vanrijiae and 3% EEP showed increased levels of antioxidants, peroxidase (POD), polyphenol oxidase (PPO), and phenol than the untreated control. Conclusion The results indicated that the combination of S. vanrijiae + 3% EEP can strongly protect lemon fruits from green mold compared with the sole application of either bioagent.

The availability of adequate information about the documentation and characterization of germplasm is fundamental for any crop improvement program. The importance of cumin as a medicinal plant yet the lack of information about its genetic variability encouraged us to initiate the current study aiming at assessing the genetic variability among 17 cumin genotypes from different geographical regions using four molecular markers (RAPD, ISSR, SRAP and SCoT). Further, the potential of six accessions to induce callus was studied under in vitro conditions on MS and B5 basal media supplemented with various combinations between 2,4-D and kinetin. Our findings showed that combining 87 primers, including 42, 15, 7 and 23 primers of RAPD, ISSR, SCoT and SRAP, respectively, facilitated detecting the relationship among the assessed cumin accessions. A total number of 765 bands were analyzed, among which only 74 bands were polymorphic. The polymorphism was low (9.67%) and varied among and within markers. The SCoT markers exposed the highest average values of polymorphism information content (0.06), resolving power (0.91) and diversity index (0.08), while ISSR induced the highest expected heterozygosity (0.06) and marker index (0.08). The UPGMA dendrogram based on data from all the molecular markers separated the genotypes into three main clusters, with a partial geographic-based relationship among the genotypes. Out of the six accessions evaluated for callus induction in vitro, five were potent to induce callus, with a frequency ranging from 90.4 to 97.5% and no significant differences among the five accessions tested using ANOVA. Two medium combinations showed superior results: MS amended with 2,4-D (4.44 mg/L) + Kin (0.22 mg/L) and B5 with 2,4-D (8.88 mg/L) + Kin (0.22 mg/L). Statistically significant variations in the relative growth rate of the produced callus were detected among accessions, where EG-4 accessions induced the highest values, followed by EG-5. All medium combinations, including 2,4-D alone, exhibited significant superiority compared with those including both 2,4-D and Kin. Our findings exposed low variability among the studied cumin accessions, implying the real need for more effort to assess wider populations from different geographic regions together with the need for reliable diversification programs.

Wood vinegar (WV) by-product of charcoal production is considered one of the most promising alternatives to synthetic pesticide and fertilizer applications, especially for organic production. Our goal in this study is to evaluate the efficacy of guava (Psidium guajava) WV to control Colletotrichum coccodes, which causes black dot disease, and how it influences potato plant development and yield. This study tested the efficacy of guava WV against the pathogen both in vitro and under greenhouse conditions. Different guava WV concentrations were tested on pathogen growth development, including 0, 0.25%, 0.50%, 1%, 2%, and 3% (v/v). Data revealed that the pathogen’s mycelial growth was significantly inhibited at all the concentrations, and the highest inhibition (100%) was obtained at 3% guava WV. In greenhouse trials conducted for two seasons (2021 and 2022), guava WV applied as a foliar spray at the concentration of 2% and 3% considerably reduced the potato black dot severity evaluated as stem colonization (average of 22.9% for 2021, average of 22.5% for 2022), root covering with sclerotia (average of 21.7% for 2021, average of 18.3% for 2022) and wilted plants percentage (average of 27.8% for 2021, average of 33.3% for 2022). Overall, guava WV also showed a positive effect on plant growth by increasing plant height, stem diameter, and tuber yield per plant of treated potato in both seasons. Gas chromatography-mass spectrometry (GC-MS) analyses revealed the presence in guava WV of phenols, esters, organic acids, antioxidants, and alcohols. In conclusion, guava WV could represent a viable alternative for potato black dot disease management and for plant growth promotion.

Abstract This study aimed to evaluate the efficiency of Enterobacter cloacae PS14 and Trichoderma asperellum T34 in the control of potato wilt, caused by Ralstonia solanacearum (Smith), under greenhouse and field conditions. In vitro, the endophyte E. cloacae PS14 caused the highest reduction of the pathogen growth among 7 screened bacteria. It produced an inhibition zone as 16.9 mm compared to a specific antibiotic (20.0 mm). E. cloacae PS14 was selected as an effective antagonistic bacterium to be compared to T. asperellum strain T34 for reduction of the disease as well as increasing the crop yield of potato plants. Both E. cloacae and T. asperellum reduced the disease severity up to 10.7–26.5%, respectively, under greenhouse and up to 26.6–36.6%, respectively, under field conditions. The results approved that both E. cloacae and T. asperellum increased the yield of the crop by 20.44–40.96%, respectively. Their mode of action was indicated by suppression of the pathogen as well as induction of plant systemic resistance. The induction of systemic resistance was confirmed by increasing the total phenol and salicylic acid contents as well as increasing the activities of peroxidase, lipoxygenase, and polyphenol oxidase in potato plants than the healthy or only infected plants. Production of siderophore, indole-3-acetic acid (0.577–0.884 μM), hydrogen cyanide (2.34–3.61 μg/ml), and salicylic acid (0.436–1.488 μg/ml) was confirmed by E. cloacae PS14 and T. asperellum T34, respectively, in vitro. The study recommends the new strain E. cloacae PS14, as new endophytic effective bacteria, in the control of R. solanacearum causing the potato wilt disease.

Abstract A study of molecular variation among Botrytis spp., the causal pathogen of scape and umbel blights of onion, as well as the biocontrol of the virulent pathogen using Bacillus subtilis PHYS7 under greenhouse conditions was carried out. Twenty-three isolates of Botrytis spp. were recovered from onion plants showing umbel blight symptoms. They were able to infect onion plants with varied severity. All Botrytis spp. produced cellulases; however, almost all of them produced pectinase. The highest activities of cellulases and pectinase were achieved by B. allii PHYOA1; however, B. cinerea PHYOC3 showed a high activity of cellulases but it failed to produce pectinase. The genetic variability among the pathogens was assessed by random amplified polymorphic DNA (RAPD) markers, using 5 random 10-mer primers: OPA03, OPA05, OPA06, OPI09, and OPW15. The results showed that 50 DNA bands ranging from 100 bp (OPA03) to 1600 bp (OPA05) were generated by the 5 primers that differentiated 9 isolates of Botrytis spp. The dual culture test showed that Bacillus subtilis PHYS77 and PHYS78 had a high antagonistic potentiality against the pathogen and involved in 60–62% reduction in its growth. Application of Ridomil Gold MZ and Bacillus subtilis PHYS77 on onion plants, 2 days after or before infection with the pathogen, significantly reduced the disease severity than the control. The study approved the molecular tool as a reliable and quick method to differentiate among the virulent and non-virulent strains of Botrytis spp. The application of B. subtilis PHYS77 as an effective biocontrol agent in the management of the onion blight disease can be recommended.

The scarcity of high-quality water resources may lead to the use of lower quality water for plant production. Quinoa (Chenopodium quinoa) plants have great potential for human nutrition, but poor water quality, such as metal contamination in wastewater, affects the seed quality. This study aims to investigate the effects of shrimp-waste-derived biochar (SWB) on the uptake of toxic metals from wastewater by quinoa plants. Additionally, the study investigates how quinoa plants’ antioxidant defenses respond to wastewater and SWB treatments. Shrimp-waste-derived biochar (SWB) was prepared by pyrolysis at 350 °C for 3 h and added to the soil at the levels of 0, 1, and 2% (based on soil weight), which are namely C, SWB1, and SWB2, respectively. SWB was applied to quinoa plants cultivated in pots filled with sandy soil and irrigated with fresh or wastewater for a continuous 90 days. The wastewater was contaminated with manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb). Quinoa seeds that were irrigated with wastewater had Cd and Pb concentrations that were above the allowable levels (for human consumption) in the absence of biochar (C) or addition of SWB1. Wastewater significantly reduced quinoa growth and photosynthetic pigments, while SWB significantly mitigated the metal toxicity and improved growth. SWB2 significantly reduced the Pb and Cd concentrations in quinoa leaves by 29 and 30% compared with C. The Cd and Pb concentrations in quinoa seeds were safe for human consumption and below the maximum allowable limits when the soil was amended with SWB2. SWB improved the synthesis of photosynthetic pigments and increased the activity of antioxidant enzymes such as polyphenol oxidase and ascorbate peroxidase. SWB reduced the toxic metal availability and uptake, mitigated the oxidative stress, and minimized the levels of malondialdehyde and hydrogen peroxide. The SWB addition stimulated quinoa’s antioxidant defense and protected plant cells by eliminating reactive oxygen species. The addition of 2% (w/w) shrimp waste biochar improved the quality of quinoa seeds irrigated with wastewater and decreased their toxic metal content. The obtained results contribute to sustainable development and the exploitation of wastewater to irrigate quinoa plants in arid degraded soil; additionally, it also helps in the recycling of shrimp waste.

Root rot disease of Cuminum cyminum caused by Fusarium solani is one of the most destructive diseases threatening cumin production. The present study investigates the biocontrol potential of some endophytes against F. solani and their effect on the induction of defense-related enzymes in a greenhouse. The results herein presented illustrate the strong biocontrol potential of three (out of twelve) endophytes. During the in vitro assay, three isolates demonstrated strong mycelial growth inhibition of F. solani: isolates 3, 4, and 9, with 87%, 65%, and 80% reductions, respectively, with respect to the control (100%). These isolates were identified as Trichoderma harzianum, T. longibrachiatum, and Chaetomium globosum, which produce siderophore and indole-3-acetic acid (IAA). Cumin seed priming with the culture filtrates of T. harzianum, C. globosum, and T. longibrachiatum positively affected the seed germination, as a higher germination (%) of culture filtrate-treated seeds was observed followed by infected and healthy control/untreated seeds. In the greenhouse, the application of T. harzianum, T. longibrachiatum, and C. globosum caused a reduction in disease severity (67.7%, 58.1%, and 59.3%, respectively) on cumin plants, with a lower disease severity (20%, 26%, and 25%, respectively) recorded in treated plants compared to the infected control (62%). Furthermore, a significant increase in defense-related enzymes in culture filtrate-treated cumin plants was recorded. Higher peroxidase (PO), polyphenoloxidase (PPO), and phenylalanine ammonia-lyase (PAL) activity, and a higher content of phenolic compounds, were found in culture filtrate-treated plants. These results indicate that the culture filtrates of these bioagents not only increased seed germination, but also protected the plants from F. solani infection by acting as important elements of the cellular antioxidant system in plants upon infection, conferring the biocontrol potential of C. globosum and Trichoderma species toward mitigating the root rot disease of cumin plants in a greenhouse.

Eleven endophytic bacteria were isolated from the roots of cumin, a medicinal plant grown in Assiut Province, Egypt. The strains KAU2025 and KAU2022 exhibited the highest inhibition rate against Fusarium oxysporum (FOC7) (64%) in dual culture test and were selected for further studies. KAU2022 and KAU2025 were identified as Brevibacillus parabrevis and Pseudomonas fluorescens, respectively, based on 16S rDNA sequence analysis. The isolates increased the seed germination of cumin by 46.6% compared to that in the control infected with the pathogen F. oxysporum (FOC7). Additionally, the biocontrol efficacy of B. parabrevis against Fusarium wilt in cumin was determined as 67.4% in pot experiments, and both the bioagents increased the fresh and dry weight of the cumin plant compared to the infected control. After a 24 h treatment, the peroxidase levels in the cumin plants were higher in the P. fluorescens and B. parabrevis-treated groups, and the level of polyphenol oxidase increased in both treatments compared to the infected control. The treatment of cumin with both strains increased the total phenol and flavonoid contents in the treated plants. In summary, B. parabrevis and P. fluorescens are promising agents for the biocontrol of Fusarium wilt in cumin.

The therapeutic importance of Balanites aegyptiaca in folk medicine for the treatment of several common human diseases has led researchers to conduct phytochemical and pharmacological studies on extracts from various parts of the plant. In the current study, the phytochemical composition of the B. aegyptiaca methanolic fruit extract was characterized, and its antimicrobial activity was evaluated together with the cytotoxic activity against MCF-7, PC-3, and Caco-2, compared with normal Vero cells. Further, its effects on cell cycle arrest, apoptosis induction and expression of apoptosis-related genes were assessed. The phytochemical screening revealed the presence of fatty acids and their esters in addition to phytosterols, steroid derivatives, and bioflavonoid glycosides with oleic and palmitic acids being the prevalent components (24.12 and 21.56%, respectively). The results showed considerable cytotoxic activity of the extract against the three cancer cell lines (MCF-7, PC-3, and Caco-2) with a selectivity index ranging from 5.07 to 6.52. This effect was further confirmed with the accompanied increased total apoptosis of treated PC-3 cells (19.22% of the total number of cells) compared to the control cells (0.64% of the total number of cells) with cell cycle arrest at G1 phase and the increased transcription of pro-apoptotic genes including P53 (3.69) and BAX (3.33) expressed as fold change (2^ ΔΔCT). The calculated minimum inhibitory concentration (MIC) was similar (62.5 µg/mL) against the three tested bacterial strains (Acinetobacter johnsonii, Serratia marcescens and Agrobacterium tumefaciens), while it was higher than 1000 µg/mL for the fungal species (Rhizoctonia solani, Penicillium italicum, and Fusarium oxysporium). Our findings suggest a promising anticancer activity for B. aegyptiaca, which paves the way for more detailed future studies.

Abstract Rhizobacteria have been reported as bioagents of bacterial diseases and plant growth promoters. The present in vitro study and greenhouse experiment aimed to evaluate the efficiency of Bacillus subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, and P. aeruginosa for the control of bacterial wilt caused by Clavibacter michiganensis subsp. michiganensis and promoting the growth of tomato plants. Effect of formulated and cell suspensions on disease reduction and the pathogen colonization frequency in plants were assessed. The tested bacterial species were able to inhibit the growth of the causal pathogen in vitro. Under greenhouse conditions, the highest reduction in disease severity was detected in tomato plants treated with formulated B. amyloliquefaciens (74.4%), followed by P. aeruginosa (66.7%), while the lowest reduction occurred in tomato seedlings treated with cell suspensions of P. fluorescens (40%) and B. subtilis (53.3%). The four bacterial species produced siderophores, hydrogen cyanide and indole acetic acid in different concentrations. The study confirmed that the use of the four bacterial species as suspensions or formulations could be applied as future eco-friendly alternatives to the synthetic fungicides for controlling the bacterial wilt of tomato caused by C. michiganensis subsp. michiganensis.

Despite the proven biological activity of the aerial part extract of Alchemilla vulgaris, scarce information is available about the activity of the root extract. This encouraged us to initiate the current investigation to study the cytotoxic activity of A. vulgaris methanolic root extract against various cancer cell lines in vitro, along with its antimicrobial activity and phytochemical screening. MTT assay was applied to test the cytotoxic effect against the prostate (PC-3), breast (MCF-7) and colorectal adenocarcinoma (Caco-2), together with normal Vero cells. Flow cytometry was employed to assess cell cycle arrest and apoptosis vs. necrosis in PC-3 cells. The expression of apoptosis-related genes (BAX, BCL2 and P53) was quantified by qRT-PCR analysis. The obtained results showed strong antiproliferative activity on the three cancer cell lines and the normal Vero cells in a dose-dependent manner. A high selectivity index (SI) was recorded against the three cell lines with PC-3 cells showing the highest SI and the lowest IC50. This effect was associated with cell cycle arrest at G1 phase and induction of total apoptosis at 27.18% being mainly early apoptosis. Apoptosis induction was related to the upregulation of the proapoptotic genes P53 and BAX and the downregulation of the antiapoptotic gene BCL2. Additionally, the extract demonstrated in vitro antibacterial activity against Agrobacterium tumefaciens, Serratia marcescens and Acinetobacter johnsoni. Additionally, it showed antifungal activity against Rhizoctonia solani, Penicillium italicum and Fusarium oxysporium. Seven phenolic acids and seven flavonoids were detected. The predominant phenolic acids were cinnamic and caffeic acids, while hisperdin and querestin were the principal flavonoids. These findings provide clear evidence about the promising proapoptotic effect of A. vulgaris root extract, which contributes to laying the basis for broader and in-depth future investigations.

Effective alternative strategies and methodological approaches are critically necessary for cancer prevention and therapy. In this study, we investigated the antitumor potential of neem fruit mesocarp and epicarp extracts. The chemical composition of the derived extracts was characterized using GC–MS. Data were collected on the antimicrobial activity of the extracts in addition to the cytotoxicity effect evaluated against PC-3, MCF-7, and Caco-2 cancer cell lines, compared with the normal Vero cells. Cell-cycle arrest, apoptosis, and expression of apoptosis-related genes were assessed on PC-3 cells. Both extracts had significant antiproliferative effects on all tested cell lines in a dose-dependent manner, with the mesocarp extract being more potent. Both extracts also showed high antibacterial and antifungal activities. These results were related to the chemical constituents of the extracts identified by the GC–MS analysis. The extract of neem fruit mesocarp caused cell-cycle arrest at G2/M phase of PC-3 cells. The cytotoxicity of neem mesocarp extract is strongly correlated with the induction of apoptosis, where it caused downregulation of the antiapoptotic BCL2 gene but upregulation of the proapoptotic P53 and BAX genes. This study showed that neem fruit extract is potential anticancer material in the future.

The importance of inorganic fertilizers in squash crop productivity is enormous. However, the continuous use of inorganic fertilizers constitutes a serious problem to the environment and human health due to nitrate accumulation. Thus, two seasons (2020 and 2021) of field trials were carried out to investigate the effects of bio-organic amendments on squash under arid land conditions in Saudi Arabia. The bio-organic amendments were comprised of humic acid (HA) at three levels (0, 50 and 100 L/ha), inoculation of a cellulose-decomposing bacterium (CDB; Geobacillus stearothermophilus SSK-2018) and wheat straw at four levels (0, 20 and 30 t/ha and NPK 20:20:20 at 600 kg/ha as a positive control). A randomized split-split plot design replicated three times was used in laying out the field trials. The independent application of HA, CDB and wheat straw significantly (p ≤ 0.05) improved squash growth, yield and water-use efficiency in both seasons. Furthermore, HA significantly (p ≤ 0.05) reduced fruits’ nitrate content. HA (100 L/ha) reduced nitrate content in squash fruits by 87% and 71.6% compared to the control in 2020 and 2021, respectively. The application of 20 t/ha of wheat straw significantly (p ≤ 0.05) reduced nitrate accumulation in fruits compared to the positive control (NPK) by 5.9% and 13.6% in 2019/20 and 2020/21, respectively. Regression analysis shows that increased nitrate accumulation in fruits results in decreased squash growth and fruit yield. This study demonstrates the significance of bio-organic amendments in improving squash growth and yield while reducing nitrate accumulation in fruits.

Shrimp waste is rich in organic compounds and essential plant nutrients, e.g., calcium (Ca), and converting these wastes to organic fertilizer is important for environmental preservation and to achieve sustainable agricultural management. In the current study, Ca-rich biochar was prepared from shrimp wastes (SWB) by pyrolysis at 300 °C. We hypothesized that the Ca-rich biochar will help in solving the problem of plant growth in saline soil by reducing sodium (Na) uptake and mitigating oxidative stress. The current study aimed to investigate the effect of SWB on the quality of saline sandy soil and the mechanism of salt resistance in pearl millet (Pennisetum glaucum L.). Pearl millet plants were planted in saline sandy soil (10 dS m−1) in wooden boxes (1.3 × 0.8 m size and 0.4 m height), and 5 doses (0, 1.0, 1.5, 2.0, and 2.5% (w/w)) of SWB were added. SWB application increased the soil quality and nutrient uptake by pearl millet plants. The highest rate of SWB increased the soil microbial biomass carbon and the activity of dehydrogenase enzyme by 43 and 47% compared to the control soil. SWB application reduced the uptake of sodium (Na+) and chloride (Cl−) and increased the K/Na ratio in the leaf tissues. SWB addition significantly increased the activity of antioxidant enzymes, e.g., ascorbate peroxidase (APX), polyphenol oxidase (PPO), and pyrogallol peroxidases (PPX). The application of 2.5% SWB to the saline soil increased the soluble carbohydrates and proline in plant leaves by 75 and 60%, respectively, and reduced the malondialdehyde (MDA) by 32% compared to the control. SWB enhanced the antioxidant defense and mitigated oxidative stress by improving the synthesis of osmoprotectants, e.g., soluble carbohydrates and proline. Sandy saline soils in arid and semiarid areas suffer greatly from low organic matter contents, which reduces the soil quality and increases the risk of salt during plant growth. The high organic matter and calcium content (30%) in the shrimp waste-derived biochar improved the quality of the saline sandy soil, reduced the uptake of toxic salts, and increased the quality of the forage material. The addition of recycled shrimp waste to saline low-fertility soils improves soil productivity and is safe for soil health.

Calotropis procera (Aiton) Dryand (commonly known as the apple of sodom, calotrope, and giant milkweed) is an evergreen, perennial shrub of the Apocynaceae family, and is mainly found in arid and semi-arid regions. Previous studies have established the toxic effects of Calotropis procera (C. procera) (Aiton). Its extract is used as one of the vital alternatives to pesticides due to its effective impacts on several pathogens and to combat insect pests that cause severe damage to several crops, but so far, its effects on combating Fusarium oxysporum f. sp. lycopersici (FOL) have not yet been evaluated. Therefore, the current study focuses on evaluating the effects of the aqueous extract of this plant on FOL by studying physicochemical indicators. In Saudi Arabia and many other countries, such disease is considered as one of the critical factors affecting tomato growth and production. For the control of Fusarium wilt disease (Fwd), many strategies have been developed, but are limited in their use. Ten isolates of the pathogens were obtained from diseased tomato plants. These isolates were able to exhibit symptoms of tomato wilt, and they varied in their virulence. Isolate No. 5 caused the highest severity of the disease (73%). According to these results, we used this isolate in the following experiment, which was identified by ITS sequences as F. oxysporum f. sp. lycopersici. Following intensive screening studies, we selected aqueous plant extract of C. procera to study its effectiveness against Fwd of tomato plants and their antifungal activity or induce systemic resistance in plants. All concentrations of C. procera extracts suppressed growth of the pathogen. The highest reduction of mycelia growth was obtained by aqueous extract at 15%, it reduced the pathogen growth to 70.2%, relative to the control. In greenhouse conditions, the aqueous C. procera extract at 5, 10, and 15% significantly reduced Fwd of the tomato compared to the infected control (52.01, 69.86, and 83.6%, respectively). The use of aqueous C. procera extract at 5, 10, and 15% significantly enhanced the fresh and dry weight of tomato plants (g plant−1) compared to inoculated plants (for fresh weight: 50, 66.6, and 86.6 and for dry weight: 60, 100, and 120%, respectively). Total phenols and flavonoids as well as antioxidant enzymes were increased in inoculated or non-inoculated tomato plants after being treated with aqueous extracts of C. procera.

Abstract The impact of six local isolates of Penicillium frequentans recovered from healthy sugar beet (Beta vulgaris L.) leaves was evaluated against Cercospora beticola, the causal pathogen of Cercospora sugar beet leaf spot under laboratory and field conditions. In in vitro studies, all the six isolates were able to inhibit the mycelial growth of C. beticola with variation in their antagonistic capability. P. frequentans isolates produce pectinase and cellulase at different degrees. There was a correlation between enzyme activity and the antagonistic ability for each isolate. The high antagonistic ability isolates had the most enzyme activity. In field studies, some adhesives such as agar, starch flour, white glue, gum, and commercial adhesive (Triton Mok) were added to conidia spore suspensions of P. frequentans at 1% to improve conidial adhesion to sugar beet plant surface. Data also showed that all adhesives increased (P = 0.05) the efficiency of the spore suspension of P. frequentans to control the disease. The starch flour at 1% gave a significant reduction in disease severity from 43.23 to 10.42% pre-infection and from 43.23 to 10.52% post-infection. The application of P. frequentans led to improved root yield and the sugar percent of sugar beet crop in two tested seasons.

The most important disease of tomato is Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL). To control this disease, this study examined the combined use of bacterial bioagents and peppermint oil (PO). Seven bacterial isolates were collected from tomato plant rhizospheres and tested in vitro against FOL. The highest growth inhibition against FOL was shown by isolate No.3. This isolate was identified using 16S rRNA sequencing gene as Bacillus amyloliquefaciens (BA). Peppermint oil tested at different concentrations (1, 2, and 3%) against FOL mycelial growth in vitro showed the highest inhibition at 3%. The effects of BA, PO, and BA + PO in vitro on the seed germination and seedling vigor index of the tomato cv. ‘Tala F1’ was also tested. All “BA, PO, and BA + PO” treatments increased the percentage of germinated seeds and seedlings’ main shoots and root length compared to control treated seeds. The BA, PO, and BA + PO treatments were further tested under greenhouse and field conditions with pre-treated seedlings in FOL-contaminated soil. Under greenhouse conditions, each treatment decreased disease severity compared to untreated seedlings. Under field conditions, pre-treatment of tomato seedlings with BA and PO treatments reduced disease severity greater than BA + PO in combination and the mock-treated plants (66.6% for BA, 66.6% for PO and 55.3% for BA + PO, respectively). These findings support the use of BA or PO as bio-control agents against F. oxysporum in tomato. The interplay between peppermint oil, B. amyloliquefaciens, F. oxysporum, and the host plant requires further study to identify the causative mechanism for this increased disease resistance.

This study aimed to evaluate the efficacy of endophytic bacterium to control common bean rust disease under greenhouse conditions. Endophytic bacterium Pseudomonas putida ASU15 was isolated from fresh asymptomatic common bean, identified using biochemical and molecular characteristics. In vitro, the inhibitory effect of different concentrations of P. putida (1 × 104, 1 × 105 and 1 × 106), as well as fungicide ortiva (0.01%) on uredospores germination of Uromyces appendiculatus were tested using water agar medium. The concentration showing the highest reduction of uredospores germination was at 1 × 106, while there was complete inhibition of uredospores germination associated with using ortiva. Scanning electron microscope exhibited the ability of P. putida cells to attack the cell wall of the fungal uredospores germ tubes of U. appendiculatus, causing obvious cell wall breakdown. The activities of chitinase, lipase, and protease produced by P. putida ASU15, in vitro, were evaluated spectrophotometrically. Chitinolytic, proteolytic, and lipolytic activities were exhibited, contributing 55.26, 3.87, and 26.12 U/mL, respectively. Under greenhouse conditions, treated plants with P. putida ASU15 (two days before pathogen inoculation or at the same time of pathogen inoculation) or fungicide reduced the disease severity, compared to the control. Applying P. putida ASU15 at the same time of pathogen inoculation showed reduction in disease severity (69.9%), higher than application before pathogen inoculation (54.9%). This study is considered the first report that demonstrates the mycoparasitic strategy of P. putida for controlling U. appendiculatus. In conclusion, our results revealed that P. putida ASU15 affords a significant disease reduction that may be attributed to direct suppression of pathogen spores germination.

Salinity impedes soil and crop productivity in over 900 million ha of arable lands worldwide due to the excessive accumulation of salt (NaCl). To utilize saline soils in agriculture, halophytes (salt-tolerant plants) are commonly cultivated. However, most food crops are glycophytes (salt-sensitive). Thus, to enhance the productivity of saline soils, gypsum (CaSO4·2H2O) as well as bio-organic (combined use of organic materials, such as compost and straw with the inoculation of beneficial microbes) amendments have been continuously recognized to improve the biological, physical and chemical properties of saline soils. CaSO4·2H2O regulates the exchange of sodium (Na+) for calcium (Ca2+) on the clay surfaces, thereby increasing the Ca2+/Na+ ratio in the soil solution. Intracellularly, Ca2+ also promotes a higher K+/Na+ ratio. Simultaneously, gypsum furnishes crops with sulfur (S) for enhanced growth and yield through the increased production of phytohormones, amino acids, glutathione and osmoprotectants, which are vital elicitors in plants’ responses to salinity stress. Likewise, bio-organic amendments improve the organic matter and carbon content, nutrient cycling, porosity, water holding capacity, soil enzyme activities and biodiversity in saline soils. Overall, the integrated application of gypsum and bio-organic amendments in cultivating glycophytes and halophytes is a highly promising strategy in enhancing the productivity of saline soils.

The aim of this study is to assess the effect of extracts of Nerium oleander, Eucalyptus chamadulonsis and Citrullus colocynthis against bacterial spot disease of tomato and to investigate the induction of resistance by tomato (Solanum lycopersicum) in order to promote a sustainable management system. The antibacterial activity of aqueous and ethanol plant extracts was tested against Xanthomonas axonopodis pv. vesicatoria, isolate PHYXV3, in vitro and in vivo. The highest antibacterial activity in vitro was obtained with C. colocynthis, N. oleander and E. chamadulonsis, respectively. In vivo, ethanol extracts of N. oleander and E. chamadulonsis were more effective than aqueous extracts in reducing pathogen populations on tomato leaves. Under greenhouse conditions, application of the plant extracts at 15% (v/v) to tomato plants significantly reduced disease severity and increased the shoot weight of ‘Super Marmande’ tomato. In most cases, plant extracts significantly increased total phenol and salicylic acid content of tomato plants compared to either healthy or infected ones. In addition, C. colocynthis and E. chamadulonsis extracts significantly increased peroxidase activity while only E. chamadulonsis increased polyphenol oxidase after infection with the causal agent. The results indicated that the plant extracts showed promising antibacterial activity and could be considered an effective tool in integrated management programs for a sustainable system of tomato bacterial spot control.

This study aims to isolate and identify the causal pathogen of tomato bacterial wilt in Egypt. In 2008, tomato plants showing typical symptoms of bacterial wilt disease with no foliar yellowing were observed in Minia, Assiut and Sohag governorates, Egypt. When cut stems of symptomatic plants were submerged in water, whitish ooze was evident and longitudinal sections showed a brown discoloration in the vascular tissues. Bacteria were isolated on triphenyl tetrazolium chloride medium and fifteen isolates shown typical morphological and cultural characteristics were confirmed as Ralstonia solanacearum biovar 2 race 1. Pathogenicity tests showed that all isolates proved to be pathogenic to tomato plants, varied from 52 to 97% wilting. This is the first report of R. solanacearum biovar 2 race 1 causing bacterial wilt in tomato crop in Egypt.