Significant Reduction In Disease Incidence Research Articles

New antimicrobials and plant defense inducers for managing citrus canker disease

For over two decades, Florida citrus growers have been heavily using copper sprays to combat citrus canker (Xanthomonas citri subsp. citri; Xcc), but it raises the risk of developing resistant bacterial strains and excessive accumulation in the soil. Alternative methods are needed to reduce copper dependency and better manage Xcc. Therefore, we screened copper-alternative products against canker on young seedlings in the greenhouse and mature trees in a commercial grove in Florida, USA. In the greenhouse, we evaluated the efficacy of single foliar application of new plant defense inducers (PDI), ‘PDI5’, ‘PDI26’, and ‘PDI31’, and a commercially available systemic acquired resistance inducer, Actigard (drench; 2g/tree), applied two days before injection-infiltration with citrus canker bacterium Xcc (104 CFU/ml), on two-year-old Valencia trees. All three PDIs, sprayed at 500 ppm, as well as Actigard (drench), effectively reduced canker severity on the inoculated leaves in the greenhouse (P ≤0.02). In the grove, we tested new antimicrobials, Mastercop ‘MC’ (21.46% copper sulfate pentahydrate; metallic copper equivalent 5.4%) at concentrations of 1.12 kg/ha, 1.68 kg/ha and 2.24 kg/ha, ‘AM’ at 1.68 kg/ha and 2.24 kg/ha, and a nutrient solution (AGRO-MOS) at 1.12 kg/ha for canker suppression on 4–6-year-old Hamlin trees. Kocide 2000 (growers’ standard control; metallic copper equivalent 30%; 3.92 kg/ha) was used as a control check. Although 2021 was not as conducive for citrus canker due to the relatively dry spring months in the field, our results showed that the six sprays of AM (2.24 kg/ha) or MC (1.68 kg/ha, and 2.24 kg/ha), in 2022, provided excellent control of Xcc, with a significant reduction in disease incidence in leaves and fruits, and disease severity in fruits, similar to Kocide 2000. The results indicate that antimicrobials, AM and MC, and plant defense inducers PDI5, PDI26, and PDI31 can be part of an integrated pest management (IPM) program with copper for managing citrus canker. Reducing the frequency and amount of copper applications can help reduce pesticide and application expenses, lower risks of copper buildup in the soil and toxicity for citrus trees and reduce the risk of the emergence of copper-resistant Xcc strains. Further research on these products is needed to assess their long-term effectiveness and potential environmental risks.

Suppression of Phytophthora capsici in Chile Pepper Using Brassica juncea and Hordeum vulgare Cover Crop Residues and Trichoderma harzianum as a Biocontrol Agent.

Phytophthora blight, caused by Phytophthora capsici, is a serious disease of many vegetable crops worldwide. In New Mexico, U.S.A., the disease affects chile pepper (Capsicum annuum L.), a major crop in the state. There is no single tool that effectively controls the disease. Continuous research is needed in identifying combination of tools that can reduce the impact of Phytophthora blight. We explored the potential of combining cover crops and biocontrol agents to reduce soilborne diseases. This study aimed to evaluate the effects of Indian mustard (Brassica juncea L.) cover crop on the antagonistic ability of Trichoderma harzianum against P. capsici in vitro and to quantify the impacts of combining soil amendment with residues from B. juncea and barley (Hordeum vulgare L.) cover crops and plastic covering on infection of chile pepper seedlings by P. capsici under greenhouse conditions. Volatiles from macerated tissue of B. juncea significantly reduced P. capsici and T. harzianum growth in the absence of soil by 89.0 and 79.0%, respectively. When incorporated in soils, volatiles from macerated tissue of B. juncea significantly reduced P. capsici and T. harzianum by 33.4 and 7.8%, respectively. T. harzianum was more resilient to B. juncea biofumigation than P. capsici. Significant reduction in disease incidence was observed with B. juncea-fumigated soil, while no disease suppression was observed with soil incorporation of H. vulgare residues. Covering soil with plastic was necessary for increasing the efficacy of B. juncea biofumigation.

Comparative evaluation of physiological and biochemical changes in black pepper plants infected by Colletotrichum siamense in response to Trichoderma viride and T. harzianum application

Black pepper (Piper nigrum L.) holds a prominent position as a globally renowned spice. Pepper vines are susceptible to various diseases, among which anthracnose stands out as a highly detrimental disease capable of severely affecting both foliage and berries. The current study was carried out to find out the effectiveness of Trichoderma viride and T. harzianum to manage the anthracnose disease of black pepper and to assess the plant innate defense response to these biocontrol agents application. Results demonstrated that foliar application of T. viride and T. harzianum, either individually or in combination, resulted in a significant reduction of disease incidence by 59.3, 67.2, and 69.8% respectively, compared to untreated infected plants. Additionally, disease severity was lowered to 71.1, 75.6, and 77.8% respectively in the treated groups. Simultaneously, these treatments exhibited a substantial promotion of black pepper growth, as indicated by increased leaf area index, number of leaves, shoot length and root length compared to the control. Physiological and biochemical analyses revealed a notable increase in chlorophyll (Chl a, Chl b, Total chl) and flavonoid content, coupled with reductions in hydrogen peroxide (H2O2), and Malondialdehyde concentrations at 48 and 96 h after treatment. Furthermore, evaluation of the superoxide dismutase (SOD) revealed a significant increase in SOD enzymatic activity following the application of the fungi, whether applied individually or in combination. Consequently, it was inferred that both T. viride and T. harzianum effectively protected black pepper plants from anthracnose by suppressing disease incidence, enhancing chlorophyll content, improving overall plant health, and inducing the innate defense system. These findings highlight the multifaceted advantages offered by T. viride and T. harzianum in terms of plant protection and growth promotion.

Melatonin application suppresses oxidative stress and maintains fruit quality of cold stored ‘Esperanza’ raspberries by regulating antioxidant system

Raspberries are highly perishable and have a short storage life. To extend its storage life, we evaluated the impact of preharvest melatonin (MEL) application (0, 50, 100, 200 µmol L−1), three days before harvest, on the activities of oxidative and antioxidative enzymes and quality attributes in ‘Esperanza’ raspberries up to 10 d cold storage. The 200 µmol L−1 MEL-treated raspberries exhibited a significant reduction in disease incidence while maintaining higher marketable fruit and activities of superoxide dismutase, glutathione reductase, dehydroascorbate reductase, monodehydroascorbate reductase, ascorbate peroxidase and catalase as compared to control. Additionally, it reduced activities of polyphenol oxidase, peroxidase and lipoxygenase enzymes and increased flavonoids and ascorbic acid levels. However, preharvest spray of 100 µmol L−1 MEL mitigated fruit weight loss and maintained higher anthocyanins, and glutathione than control. In conclusion, MEL application (100–200 µmol L−1), three days before harvest, supressed oxidative stress by maintaining higher activities of antioxidant enzymes in raspberries during 10 d of cold storage.

Enhancement of soil suppressive potential to bacterial wilt disease caused by Ralstonia solanacearum

The effect of wheat and maize rotations and the application of plant-animal compost on potato bacterial wilt and yield was investigated. The proposed method was tested in three separate locations, each two acres in size, with an untreated control. The first two were naturally infested, but the third was pathogen-free. Infested locations that had been treated experienced a significant reduction in disease incidence. The addition of a bio-fertilizer mixture (Azotobacter sp., Azospirillum sp., Bacillus megaterium, and Bacillus circulans) improved the compost’s suppressive potential. The method increased soil organic matter (SOM), N, P, K, Ca+2, and Mg+2 while decreasing Na+ levels and increasing potato yield. The relative abundance of Ralstonia decreased while that of Arthrobacter, Streptomyces, and Nocardioides increased. The presence of Gracilibacillus, Cellvibrio, Bacillus, and Paenibacillus was associated with a decrease in Ralstonia, whereas the presence of Propionibacterium (a nitrogen-fixing bacteria) was associated with an increase in Ralstonia.

Exploring the Potential of Green Silver Nanoparticles from Berberis vulgaris against Bacterial Spot of Tomato and its Surveillance in Poonch District

Bacterial spot of tomato is a major constraint to tomato production in tropical, subtropical, and temperate climates, leading to significant crop losses. The current study aimed to manage the highly devastating disease bacterial spot of tomato, caused by Xanthomonas perforans, using green silver nanoparticles based on Berberis vulgaris plant extract. Disease parameters, namely disease prevalence and disease incidence, were calculated from tomato growing areas of district Poonch, AJK, to document the current status of bacterial spot disease on local tomato cultivars. The associated pathogenic strains were purified, and virulence study was conducted on healthy tomato seedlings followed by characterization using morphological, biochemical, and molecular analysis. B. vulgaris plant extract was used for the preparation of green silver nanoparticles (AgNPs), and three different concentrations were prepared (0.2%, 0.4%, and 0.6%). For texture and molecular composition study, characterization of green AgNPs was done using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Green silver nanoparticles were then evaluated using the inhibition zone technique in the lab, and it was found that the maximum inhibition zone of 24.32 mm was observed at a 0.6% concentration. Similarly, in the greenhouse experiment, the minimum disease incidence was recorded in the treatment with a 0.6% concentration of green AgNPs. The results of the current study showed a significant reduction in disease incidence while using green silver nanoparticles against bacterial spot of tomato

Evolução temporal da anemia em crianças de seis a 59 meses no estado de Pernambuco, Brasil, 1997 a 2016

ABSTRACT Objective: To analyze the temporal evolution of anemia in children aged six to 59 months in Pernambuco, based on population surveys from 1997, 2006, and 2016 and the factors associated with the situation in 2016. Methods: The field studies took place in the participants’ households, in the Recife Metropolitan Area, as well as in the urban and rural inland. The trend study of anemia in children used data from the State Health and Nutrition Survey (Pesquisa Estadual de Saúde e Nutrição — PESN) II (40.9%) and III (32.8%). Data from PESN IV were collected using questionnaires administered to families to verify socioeconomic and individual conditions, as well as anthropometric — weight and height — and biochemical — hemoglobin — records. We adopted the test for trend in proportion for the time trend study and Poisson regression for hypothesis tests for the associated factors. Statistically significance was set at a p-value<0.05. Results: In 2016, the prevalence of anemia was 24.2%, indicating a significant reduction in disease incidence. In children aged 6–23 months, this number decreased from PENS II and III to PENS IV — 63 and 55.6 to 37.7% (p<0.001), respectively. In 2016, the statistically significant variables for anemia in children were maternal hemoglobin, child's age, current or recent case of diarrhea, and weight-for-age index Conclusion: Between 1997 and 2016, anemia rates decreased, showing an epidemiological trend that can contribute to continuously improve the health of children under five years of age in Pernambuco.

Temporal evolution of anemia in children aged six to 59 months in the state of Pernambuco, Brazil, 1997 to 2016

To analyze the temporal evolution of anemia in children aged six to 59 months in Pernambuco, based on population surveys from 1997, 2006, and 2016 and the factors associated with the situation in 2016. The field studies took place in the participants' households, in the Recife Metropolitan Area, as well as in the urban and rural inland. The trend study of anemia in children used data from the State Health and Nutrition Survey (Pesquisa Estadual de Saúde e Nutrição - PESN) II (40.9%) and III (32.8%). Datafrom PESN IV were collected using questionnaires administered to families to verify socioeconomic and individual conditions, as well as anthropometric - weight and height - and biochemical - hemoglobin - records. We adopted the test for trend in proportion for the time trend study and Poisson regression for hypothesis tests for the associated factors. Statistically significance was set at a p-value<0.05. In 2016, the prevalence of anemia was 24.2%, indicating a significant reduction in disease incidence. In children aged 6-23 months, this number decreased from PENS II and III to PENS IV - 63 and 55.6 to 37.7% (p<0.001), respectively. In 2016, the statistically significant variables for anemia in children were maternal hemoglobin, child's age, current or recent case of diarrhea, and weight-for-age index. Between 1997 and 2016, anemia rates decreased, showing an epidemiological trend that can contribute to continuously improve the health of children under five years of age in Pernambuco.

Endophytic Beauveria bassiana can protect the rice plant from sheath blight of rice caused by Rhizoctonia solani and enhance plant growth parameters.

Beauveria bassiana, a potential entomopathogenic biocontrol agent, has recently drawn attention worldwide for its other additional beneficial roles such as plant disease antagonist, beneficial rhizosphere colonizer, plant growth promoter and an endophyte. In the present study, endophytic colonizing behaviour of five (5) B. bassiana isolates viz., Bb4, Bb16, Bb25, Bb44 and Bb53 were studied in rice following three (3) artificial inoculation techniques viz., seed treatment, root inoculation and foliar spray and the endophytic colonizing ability were determined by culture-based assay. After B. bassiana inoculation, rice plants were challenged with Rhizoctonia solani and disease incidence and plant growth promotion were assessed. Per cent colonization of rice stems, leaves and roots were influenced by inoculation technique, post-inoculation time (7th, 14th, 21st and 28th dpi) and plant growth medium (sterile soil, non-sterile soil), recorded maximum on 14th-day post-inoculation (dpi) i.e., 96% in stems, 92% in leaves and 28% in roots, whereas, lower colonization was recorded on 7th, 21st and 28th dpi. Whereas, the foliar spray was found best as compared to seed and root inoculation techniques, and maximum fungal recovery was observed in stems and leaves and least in roots. Upon colonization, the physical presence of B. bassiana in rice was localized by light microscopy-based studies. Potential B. bassiana strains with endophytic ability were re-isolated and their identity was determined based on morphometric and PCR-based techniques. Further, the present study also identified several virulent genes viz., BbChit1, Cdep1, Bbhog1 and Bbjen1 and extracellular hydrolytic enzymes viz., α-amylase, cellulase, lipase, pectinase and xylanase secreted by endophytic B. bassiana strains as determinants responsible for establishing the endophytic association in rice. On the other hand, a significant reduction in disease incidence was observed in the endophytic B. bassiana Bb4-, Bb16- and Bb44-inoculated plants as compared to the non-endophytic B. bassiana Bb25- and Bb53-inoculated plants along with enhanced plant growth promotion. This is one of the few studies investigating the colonization of B. bassiana in rice and its promising role as a plant disease antagonist and plant growth promoter in rice.

Bacillus subtilis suppresses the charcoal rot disease by inducing defence responses and physiological attributes in soybean.

Endophytes can induce the defence responses and modulates physiological attributes in host plants during pathogen attacks. In the present study, 127 bacterial endophytes (BEs) were isolated from different parts of healthy soybean plant. Among them, two BEs (M-2 and M-4) resulted a significant antagonistic property against Macrophomina phaseolina, causes charcoal rot disease in soybean. The antagonistic potential was evaluated through dual culture plate assay, where M-4 expressed higher antifungal activity than M-2 against M. phaseolina. The M-4 produces cell wall degrading enzymes viz. cellulase (145.71 ± 1.34 μgmL-1), chitinase (0.168 ± 0.0009 unitmL-1) and β,1-3 endoglucanase (162.14 ± 2.5 μgmL-1), which helps in cell wall disintegration of pathogens. Additionally, M-4 also can produce siderophores, indole-3-acetic acid (IAA) (17.03 ± 1.10 μgmL-1) and had a phosphate solubilization potential (19.89 ± 0.26 μgmL-1). Further, GC-MS profiling of M-4 has been carried out to demonstrate the production of lipophilic secondary metabolites which efficiently suppress the M. phaseolina defensive compounds under co-culture conditions. Bio-efficacy study of M-4 strain shown a significant reduction in disease incidence around 60 and 80% in resistant and susceptible varieties of soybean, respectively. The inoculation of M-4 potentially enhances the physiological attributes and triggers various defence responsive enzymes viz. superoxide dismutase (SOD), phenol peroxidase (PPO), peroxidase (PO) and catalase (CAT). The histopathological study also confirmed that M-4 can reduce the persistence of microsclerotia in root and shoot tissue. Conclusively, M-4 revealed as an efficient biocontrol agent that can uses multifaceted measures for charcoal rot disease management, by suppress the M. phaseolina infection and enhance the physiological attributes of soybean.

Response of modified microclimates on growth, yield, and incidence of rhizome rot disease of ginger in Assam, India.

Field experiments were conducted at Biswanath, Assam, India (26° 42' N and 93° 15' E), during 2016, 2017, and 2018, to evaluate the effect of microclimates on growth, yield, and disease incidence in the ginger crop. The ginger variety Nadia was grown under six microclimates, viz., under shade net for the entire crop season (T1), under shade net from planting to mid-October (T2), with pigeon pea (T3), with maize (T4), with okra (T5), and as a sole crop (T6) in three replicated RBD. Photosynthetically active radiation (PAR), net radiation (Rn), temperature above the ginger canopy, soil temperature, and soil moisture were measured during the critical crop growth period under different microclimates. Recording of rhizome rot disease incidence was done periodically and genomic analysis of pathogen was carried out. PAR recorded above the ginger canopy under T6 was 1688.1 μ mol s-1m-2, which was attenuated up to 80.1% in other microclimates. The Rn load of the ginger canopy was maximum (446.4Wm-2) under T6, which reduced to below 50Wm-2 under both T3 and T4. Both air temperatures above the ginger canopy and soil temperatures under T3 and T4 were reduced by 3.3°C and 4.6°C, respectively, as compared to T6. The pathogen causing the disease in the experimental site was identified as Fusarium oxysporum. Considerable increase in soil and air temperature and soil moisture favored disease incidence (90.3%) under shade net (T1 and T2) treatments, while opposite reason causing significant reduction in disease incidence (16.1%) was observed under T3 and T4. More yield of ginger recorded in treatments T3 (6.21 t ha-1) or T4 (6.48 t ha-1) was attributed to better crop growth and diminutive disease incidence, while the crop was almost damaged due to severe disease incidence under shade net (T1 and T2) treatments.

Antagonistic activity of lipopeptide-biosurfactant producing Bacillus subtilis AKP, against Colletotrichum capsici, the causal organism of anthracnose disease of chilli

Research for the development of biological control agents as an alternative to agrochemicals for controlling plant pathogens has gained considerable attention for the acquirement of agricultural sustainability. The present study reports a qualitative assessment of the potential of one promising antagonistic bacteria isolated from soil collected from Ultapani reserve forest, Assam, India, identified as Bacillus subtilis isolate AKP based on the morphological, biochemical, and molecular characteristic (NCBI GenBank Accession no. MW052029). The bacteria exhibited antagonistic activity against Chilli anthracnose fungus Colletotrichum capsici (61.5% growth inhibition in dual culture plate assay) which established the basis of further investigation. The strain AKP was found to exhibit biosurfactant producing ability with high emulsification index (83.1%) and surface tension reduction activity (83.8 to 21.9 ± 0.21). The crude extract from AKP strain also caused a significant reduction in disease incidence (anthracnose symptoms) by 16.66 ± 0.23% thus, providing good biocontrol efficiency against C. capsici based on in-vitro detached fruit assay. B. subtilis AKP showed the presence of surfactin (srfAA), iturin (ituC), and fengycin (fenD) antimicrobial biosynthetic genes in PCR assay. LC-MS analysis identified different homologues of surfactin, iturin, and fengycin lipopeptide biosurfactant from the methanolic fraction. Furthermore, the application of cell suspension-based B. subtilis also showed potentials for plant growth promotion both under in-vitro assays as well as in-vivo conditions in pot experiments. Our study revealed the potential of B. subtilis AKP in suppression of C. capsici as well as plant growth promotion which can be used on a commercial scale for the management of Anthracnose disease.

Salicylic acid and nitric oxide cross-talks to improve innate immunity and plant vigor in tomato against Fusarium oxysporum stress.

Foliar application of SA cross-talks and induce endogenous nitric oxide and reactive oxygen species to improve innate immunity and vigor of tomato plant against Fusarium oxysporum stress. The present investigation was aimed to demonstrate the efficacy of salicylic acid (SA), as a powerful elicitor or plant growth regulator (PGR) and its cross-talk with nitric oxide (NO) in tomato against the biotic stress caused by wilt pathogen, Fusarium oxysporum f. sp. lycopersici. Different defense-related enzymes and gene expression, phenol, flavonoid, and phenolic acid content along with NO generation and other physiological characters have been estimated after foliar application of SA. Total chlorophyll content was steadily maintained and the amount of death of cells was negligible after 72h of SA treatment. Significant reduction of disease incidence was also recorded in SA treated sets. Simultaneously, NO generation was drastically improved at this stage, which has been justified by both spectrophotometrically and microscopically. A direct correlation between reactive oxygen species (ROS) generation and NO has been established. Production of defense enzymes, gene expressions, different phenolic acids was positively influenced by SA treatment. However, tomato plants treated with SA along with NO synthase (NOS) inhibitor or NO scavenger significantly reduce all those parameters tested. On the other hand, NO donor-treated plants showed the same inductive effect like SA. Furthermore, SA treated seeds of tomato also showed improved physiological parameters like higher seedling vigor index, shoot and root length, mean trichome density, etc. It is speculated that the cross-talk between SA and endogenous NO have tremendous ability to improve defense responses and growth of the tomato plant. It can be utilized in future sustainable agriculture for bimodal action.

Bacillus amyloliquefaciens strain QST713 may contribute to the management of SDHI resistance in Botrytis cinerea.

Resistance of Botrytis cinerea to SDHI fungicides is widely distributed throughout the world and is associated with mutations in sdhB, differentially affecting mutant sensitivity to several succinate dehydrogenase inhibitors (SDHI) and the fitness of the strains. This study was initiated to test the hypothesis that Bacillus amyloliquefaciens QST713 (Ba QST713) can be utilized in Integrated Pest Management (IPM) programs aiming to control grey mould and eliminate sdhB mutants (H272R/Y, N230I and P225F/H/L). Protective and curative applications of Ba QST713 on artificially inoculated bean plants resulted in a significant reduction of disease incidence and severity. Competition experiments between sdhB mutants and wild-type isolates conducted either in the absence of any treatment or in the presence of Ba QST713 or fluopyram showed a dominance of sensitive strains over the mutated strains on untreated and Ba QST713-treated plants. Additionally, the efficacy of Ba QST713 in controlling grey mould and its effects on the selection of sdhB mutants was assessed in a greenhouse experiment. The applications of Ba QST713 in alternation schemes with fluopyram provided high control efficacy and reduced SDHI resistance frequency. The results of the study showed that Ba QST713 can contribute both to moderate/high levels of grey mould suppression and to a reduction in SDHI resistance frequency. Thus, Ba QST713 can be an efficient tool for SDHI resistance management of B. cinerea in the field. © 2020 Society of Chemical Industry.

Application of alternative treatments to control postharvest fungal infection and shelf life extension of papaya in different maturity stages

An experiment was conducted to study the application of alternative treatments to control postharvest fungal infection and shelf life extension of papaya under different maturity stages at the Laboratories of the Department of Horticulture and Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh during the period from August to October, 2018. The two factor experiment (maturity stages and postharvest treatments) was laid out in a completely randomized design (CRD) with three replications. Four postharvest treatments viz., control, hot water treatment (Fruits treated at 50±2ºC for 10 minutes), chitosan coating (2000ppm chitosan solution) and hot water+chitosan coating were assigned to papaya fruits which were maturity stage I or maturity stage II. Significant variations were observed between maturity stage I (green mature) and maturity stage II (0-10% yellowing of fruits) in relation to most of the parameters studied. Results showed that most of the parameters studied were significantly influenced by the afore-mentioned factors. Longer shelf life (12.64 days) was observed in maturity stage I fruits than maturity stage II fruits (12.18 days). Significant reduction in disease incidence and severity was noticed in the maturity stage I fruits as compared to maturity stage II fruits. The longest shelf life (15.20 days) was found in hot water treated and chitosan coated fruits of maturity stage I, whereas the shortest shelf life (8.52 days) was observed in control of maturity stage II fruits.&#x0D; Progressive Agriculture 30 (3): 298-304, 2019

Bio-management of Citrus Nematode, Tylenchulus semipenetrans and Dry Root Rot Fungi, Fusarium solani under Laboratory and Field Conditions

Slow decline and dry root rot of citrus caused by Tylenchulus semipenetrans and Fusarium solani, respectively are serious diseases attacking many groves in Egypt. Efficacy of the bio-agents (Trichoderma harzianum, Bacillus subtilis, Streptomyces griseus and Paecilomyces lilacinus) against citrus nematode T. semipenetrans and their combination with Nemastop were studied in vitro. Such bio-agents and Nemastop were also studied under field conditions against both T.semipenetrans and F. solani infecting Washington Navel orange trees compared with control and Nemaphos. In vitro study revealed that all tested bio-agents had various degrees of effectiveness towards the juvenile's survival compared with control treatment. Meanwhile, Bio-Nematon achieved the highest percentage of mortality for T. semipenetrans (50.0%). The population and incidence of soil borne pathogens were examined after three, seven and twelve months in vivo. Results showed that all treatments led to clear significant reduction in disease incidence compared with control treatment. All bio-agents gave good effect on decreasing T. semipenetrans population and F. solani incidence for twelve months. Benefits, achieved by simultaneous application of bio-agents based on different mechanisms of actions, are discussed. A clear significant decrement in T. semipenetrans population was noticed with the combination of T. harzianum with Nemastop. Meanwhile, B. subtilis or T. harzianum reduced F. solani incidence.

Comparative Study on Effects of Chemical Fungicides and a Biocide on Cotton Seedling Damping-Off Caused by Rhizoctonia solani

The present study evaluated the efficacy of the fungicides Moncut and Rizolex-T and the biocide Bio-Control T34 (Trichoderma asperellum) on suppressing incidence of cotton seedling damping-off caused by Rhizoctonia solani on cotton cultivar Giza 86. The dual treatments of the two fungicides and the biocide also evaluated in vitro and in vivo. In vitro studies showed that Moncut completely inhibited R. solani linear growth when it was applied at a rate of 250ppm, while Rizolex-T completely inhibited R. solani growth when it was applied at a rate of 125ppm. The biocide inhibited the linear growth of R. solani by 59.17%. The biocide growth was not affected by all the applied concentrations of Moncut, while it was partially inhibited by the high concentrations of Rizolex-T. Under greenhouse conditions, the two chemical fungicides suppressed incidence of damping–off, while the biocide was unable to suppress the disease. The use of Moncut before or after the biocide succeeded in reducing the disease incidence. On the other hand, Rizolex-T caused significant reduction in disease incidence only when it was applied before the biocide. The application half or fourth the initial dose of the chemical fungicides before or after the biocide caused significant reduction in the disease incidence. The application of Moncut by the initial dose followed by the biocide caused increases in the activity of polyphenol oxidase (PPO) and phenols and sugars contents of the seedlings. Application half the initial dose of Moncut before or after the biocide caused increases in the previously mentioned variables. The use fourth the initial dose of Moncut caused increases in the same variables when it was followed by the biocide, while the use of this dose after the biocide caused decreases in the same variables.

Antifungal Activity of Spearmint and Peppermint Essential Oils against Macrophomina Root Rot of Cotton

Essential oils as natural antifungal substances one of the alternative methods for plant disease control. The present study was conducted during 2015 and 2016 to investigate the antifungal activity and oil constituents of volatile oils from spearmint (Mentha viridis L.)and peppermint( Mentha piperita L.) against cotton root rot pathogen (Macrophomina phaseolina). Gas chromatographic analysis revealed that spearmint volatile oilwas constituted by carvone (60.16%) as a major component followed by 1,8 cineole (8.67%), limonene (7.40 %), dihydro carvone (5.86 %), β- ocimene (4.29%) and pulegone (3.23%). While peppermint volatile oilwas rich in menthone (46.52%), menthol (25.88%), limonene (7.72%) menthyl acetate (3.90%), iso menthol (2.10%) and sabinene (2.03%). Both essential oils with different concentrations were evaluated in vitro against three fungus isolates. The two tested oils exhibited 89.55 inhibition percent for the crude oils, against all the tested fungal isolates. Moreover, it was noticed that as oil concentrations decreased, the inhibitory effect also decreased. At the same time, a highly significant effect of oils at all concentrations was observed during sclerotial formation (number and size). The use of essential oils as seed treatment exhibited a highly significant reduction in disease incidence of cotton which has been artificially infested with root rot patho­gen, compared to fungicide and untreated control treat­ments under the greenhouse conditions. This reduction was calculated to be between 4.56 and 100% compared with a 26.67% reduction with the utilization of Topsin M treatment at the pre-emergence stage. At the post-emergence stage, all applied treat­ments were able to decrease the percentage of root-rot incidence. Reduction ranged between 66.67 and 100% over the untreated control. Reduction in disease incidence was reflected in a survival plants increase of 34.62–96.17% and 73.09–126.9% for spearmint and peppermint volatile oils, receptively. Results in the current study demonstrated, that application of peppermint essential oils has an observer influence on the plant growth (plant height), which differ significantly from this of spearmint oil.

Seed inoculation with endophytic fungal entomopathogens promotes plant growth and reduces crown and root rot (CRR) caused by Fusarium culmorum in wheat.

Fungal entomopathogens, Beauveria bassiana (NATURALIS) and Metarhizium brunneum (BIPESCO5), can promote the growth of wheat following their endophytic establishment within plants through seed treatment. Similar to endophytic B. bassiana which has already been reported as a disease antagonist by several previous studies, the present study demonstrates that M. brunneum can suppress disease pathogens following plant colonization as well. An upsurge of research hints at the ability of entomopathogenic fungi, almost exclusively considered and used as insect pathogens, to endophytically colonize the internal tissues of a wide array of host plants and subsequently confer numerous benefits including enhancement of plant growth and suppression of disease pathogens. Such an ability has mainly been investigated for Beauveria bassiana. Fewer studies have demonstrated plant growth promotion by Metarhizium brunneum colonization, whereas no studies have reported on the potential of endophytic M. brunneum as a plant disease antagonist. The present study was, therefore, conducted to investigate whether seed treatment with B. bassiana (NATURALIS) and M. brunneum (BIPESCO5) could result in their endophytic establishment in wheat and promote plant growth. The study further examines the effect of the fungal strains as endophytes against Fusarium culmorum, one of the main causal agents of crown and root rot (CRR) in wheat. Both B. bassiana and M. brunneum were able to systemically colonize roots and shoots of wheat, and promote several plant growth parameters (shoot height, root length, and fresh root and shoot weights). Moreover, endophytic colonization of wheat with either fungal entomopathogen resulted in a significant reduction in disease incidence, development and severity. These results support the notion of the multiple ecological roles that could further be played by entomopathogenic fungi. Bearing such additional roles in mind while developing these fungi as microbial agents could improve the value of many commercially available mycoinsecticides.

Controlling Maize Late-Wilt and Enhancing Plant Salinity Tolerance by Some Rhizobacterial Strains

The effects of plant growth promoting rhizobacteria (PGPR) on decreasing maize late wilt disease caused by Cephalosporium maydis, enhancing plant tolerance to salinity stress and plant growth parameters were studied. In vitro, four out of the seven Pseudomonas fluorescens isolates and three out of nine isolates of Bacillus subtilis showed the potency to cease the growth of all target pathogens. Significant reduction in disease incidence was recorded under greenhouse and field conditions in seeds treated by PGPR strains either individually or in combination. PGPR seed coated treatments carried on biochar were the best which reduced the disease to 72% in normal soil and 70% in saline soil under greenhouse conditions, whereas, it gave 82.8% disease reduction in normal soil and 79.3% in saline soil in the field. This treatment promoted seed germination percentage, plant height, dry weight and chlorophyll levels more than other treatments. Also, seed treatments with rhizobacteria decreased the proline induction compared with untreated plants in normal and saline soil due to decrease of salinity stress by PGPR especially that carried on biochar. Under field conditions in normal and saline soil, rhizobacteria seed coating carried on biochar either alone or in combination significantly decreased disease infection and enhanced the plant yield compared with control.