Percent Disease Incidence Research Articles

Identification and disease severity of dieback disease on sengon seedlings in Persemaian Permanen Dramaga Bogor

Sengon is one of the forestry plant commodities favoured by the community. So that the provision of healthy seedlings in the nursery is significant to achieve successful planting. However, sengon is very susceptible to several diseases. One of the diseases is dieback in the nursery. This study aims to calculate the incidence and severity of shoot death in sengon seedlings in Persemaian Permanen Dramaga Bogor and identify the types of pathogens that cause dieback in sengon seedlings. Methods of data collection were carried out using the census and scoring methods. In addition, the identification process was carried out under a light microscope with a magnification of 40×10. Data analysis was performed using descriptive analysis. The percentage of disease incidence and dieback severity in sengon seedlings were 10.809% and 73.764%, where the severity of the disease is declared as severe. Based on the identification results, the fungus Rhizoctonia sp. is suspect as the cause of dieback in sengon seedlings.

Varietal performance against blast and cercospora leaf spot of finger millet under different cultivation schemes

Finger millet is the fourth-ranked cereal crop after rice, maize, and wheat in Nepal and ranks first among the mandate hill crops in terms of importance and priority. However, the blast disease caused by Pyricularia grisea and cercospora leaf spot caused by Cercospora eleusinis is reported to cause a significant reduction in the production of this crop. Therefore, the investigation was conducted at the research farm of the Institute of Agriculture and Animal Science, Sundarbazar, Lamjung, from June to November 2016 to compare varietal resistance and cultivation schemes against blast and cercospora leaf spot. The experiment was laid out in a split-plot design where four varieties of finger millet; Okhale 1, Kabre Kodo 1, Dalle Kodo 1, Kabre Kodo 2 were kept as the main plot factor while planting methods; System of Crop Intensification and Conventional transplanting were kept as subplot factor and replicated thrice. Scoring was done based on the recommended scale of (0-9) at 7-day intervals for leaf blast and cercospora leaf spot. In addition, the percentage of disease incidence was calculated for neck and finger blast. The area under the disease progress curve (AUDPC) and disease severities were not significantly different between tested varieties and planting methods for both diseases. Comparing neck blast incidence, Kabre Kodo1 showed the highest incidence of 1.85%. However, the finger blast was more on Dalle 1 with 1.81% incidence and the conventional transplanting method showed an incidence of 1.26%.

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The damaging potential of Alternaria alternata on different mungbean genotypes was accessed and its management was done under in vitro and in vivo conditions through suitable fungicides. Seeds of fifty different mungbean genotypes were sown in lines. There were fifteen replications for each line. The data on disease incidence and percent disease intensity were accessed on all the genotypes. Infection was observed on all genotypes, none of them were found to be immune. Fourteen lines were found to be the most susceptible (14114, 14117, 14128, 14198, 14203, 14205, 14250, 14265, 14266, 14295, 14305, 14306, 14368, 14438). Infection was observed on all genotypes, none of them were found to be immune. The maximum PDI (Percent Disease Intensity) was recorded 35.30% while minimum was 2.43%. For detached leaf assay, the conidial suspension of 105 conidia/mLwas prepared and sprayed on detached leaves. The results revealed that maximum infection percentage was observed in 14306, 14198 genotypes while minimum was observed in 14128, 14203. The lesion area was found to be maximum in 14306, 14198 (0.23, 0.22) while minimum in 14128 (0.12) respectively. For management experiments, different fungicides; Propiconazole (Tilt), Propineb (Antracol), Difenconazole (Score), Thiophanate methyl (Topsin M), Mancozeb (Dithane M45) were tested under in vitro and in vivo conditions. Significant decrease in mycelial growth with the increase in concentration of fungicides was observed. Percent inhibition of mycelial growth was maximum in Propiconazole at its highest concentration (1000 ppm) under in vitro conditions. A significant decline in disease incidence was observed as compared to control treatment. The minimum percent disease incidence was recorded in Propiconazole (10.34) with PDC (67.31) while the maximum percent disease incidence was observed in Thiophanate methyl (25.46). So, Propiconazole could be used successfully for the management of A. alternata under field conditions.

Bio-priming of Aceh local chili seeds in the effort to increase production and begomo virus resistance

The purpose of this study was to determine whether P60 could induce resistance in local Aceh chili varieties to begomovirus and compared with national varieties. This research was conducted at the Experimental Farm, Genetics and Plant Breeding Laboratory, Faculty of Agriculture, Syiah Kuala University, Banda Aceh, from March to July 2021. This study used a factorial randomized block design. The tested factors consisted of two factors. The first factor is bio priming. The second factor consists of four local Aceh chili varieties, namely: V1 = Odeng, V2 = Lanyoe, V3 = Super Lamando and V4 = LamandoLapaben and one national variety, namely V5 = Baja F1 as a comparison variety. The results showed that the best local Aceh variety was LamandoLapaben for the variables of resistance response, incubation period, disease intensity, disease incidence, stem diameter, and crown width. The best local variety Aceh Lanyoe on plant height and dichotomous height parameters. Giving P60 can reduce the percentage of disease incidence by 52.00% and slow down the process of emergence of disease symptoms (incubation period) 27.11 DAP. The best combination treatment was the LamandoLapaben variety, which was 1.41 milligram Units-1 (Umg)-1.

Response of Silica Enriched Nutrient Management on Pest Infestation and Disease Incidence of Okra

An investigation conducted at open field of Horticulture farm, Department of Horticulture, Rajasthan College of Agriculture, MPUAT, Udaipur during two consecutive seasons of 2019 and 2020. The factorial experiment was laid out in split plot design with three replications, assigning Seven levels of silica enriched nutrient management (Control, 25 tonnes FYM/ha + Silica Diatomaceous 2%, RDF + Silica diatomaceous 2%, RDF + 25 tonnes FYM/ha + Silica diatomaceous 2%, RDF + 25 tonnes FYM/ha + Silica diatomaceous 4%, RDF + 25 tonnes FYM/ha + Silica diatomaceous 6% and RDF + 25 tonnes FYM/ha + Silica diatomaceous 8%) and four levels of spray scheduling (Three weeks after sowing, Five weeks after sowing, Seven weeks after sowing and Nine weeks after sowing). The whole field was divided into three blocks each representing a replication and each replication consists of 28 treatments combination. The results showed that silica enriched nutrient management levels non-significantly improved insect pest and disease incidence percentage of okra crop during both the years of investigation. The maximum growth attributes was recorded with RDF + 25 t FYM/ha + silica diatomaceous 8% (F7) being at par with RDF + 25 t FYM/ha + silica diatomaceous 6% (F6) and RDF + 25 t FYM/ha + silica diatomaceous 4% (F5) during first and second year of investigation. Spray scheduling also significantly enhanced growth, yield attributes and yield of okra crop and recorded maximum values with S1(three weeks after sowing) being at par with S2(five weeks after sowing) during both the years of The investigation.

Flagellin and elongation factor of Bacillus velezensis (VB7) reprogramme the immune response in tomato towards the management of GBNV infection

The present study investigates the reprogramming of plant defense system, upon interaction with MAMP (Microbe Associated Molecular Pattern) gene products including, flagellin (Flg) and elongation factor (EF-Tu) of Bacillus velezensis (VB7) and groundnut bud necrosis virus (GBNV) in tomato (Shivam). The MAMP gene products induced the plant defense genes including, PAL, PPO, LOX, JAR, MYC2 and PDF 1.2. Secondary metabolites of Bacillus spp. at 1000 parts per million (ppm) concentration effectively reduced GBNV symptom expression in cowpea (CO7) up to 83.1 % compared to untreated, GBNV inoculated, control. The secondary metabolites from B. velezensis (VB7) and B. licheniformis (Soya 1) reduced GBNV symptoms in cowpea (CO7) up to 1.7 lesions/cm2 leaf area compared to 8.6 lesions/cm2 in virus inoculated control. Further, field study revealed that the combined application of B. velezensis (VB7) and B. licheniformis (Soya1) at 1% (10 mL/L) as, soil and foliar application reduced the percent disease incidence (PDI) up to 10.5 (PDI) compared to 28.4 (PDI) in untreated control plants. Besides, it also improved the plant growth and yield up to 23.5 tonnes/ha compared to 13.8 tonnes/ha in untreated control.

Terpinen-4-ol from Trachyspermum ammi is a potential and safer candidate molecule for fungicide development against Alternaria solani

Phytopathogenic fungi are serious threats to fruit and vegetable production. Use of plant essential oil (PEO), as antifungal agents, have been in practice for many years. Essential oils (EO) of five plants i.e., Trachyspermum ammi, Cuminum cyminum, Azadirachta indica, Citrus sinensis and Eucalyptus grandis were tested against Alternaria solani in tomato. The trials consisted of laboratory testing (MIC and MFC), field testing and Computer Aided Fungicide Design (CAFD) of PEOs against A. solani. Each PEO was used at 10 and 25 µl/ml concentrations to asses MIC, while MFC was assessed at 25, 50 and 75µl/ml concentration. Trachyspermum ammi EO at 25µl/ml concentration showed the largest inhibition zone (37.3 mm) followed by a not significantly different zone(20.6 mm)produced by C. cyminum EO. No fungal growth was observed at 50µl/ml concentration of T. ammi while, at 75µl/ml for A. indica and C. cyminum. In foliar application, T. ammi EO showed lowest percent disease incidence (2.2) which was not significantly different from that of C. cyminum. Trachyspermum ammi EO, qualified in laboratory and field trials, was selected for CAFD. Compounds of T. ammi PEO docked against toxin producing enzyme, solanapyrone synthase, of A. solani. Terpinen-4-ol was qualified as a lead compound against A. solani.

Influence of weather parameters on powdery mildew of mango inflorescence in humid tropics of South Gujarat

The influence of environmental parameters on the development of powdery mildew caused by Oidium mangiferae Berthet on mango inflorescence was studied for seven consecutive years (2012-18) in humid tropics climatic conditions of South Gujarat. The disease incidence and severity (DIS), area under disease progress curve-AUDPC (A-value) and apparent infection rate (r-value) were recorded at panicle and fruit setting stages of the tree at weekly intervals. The correlation studies showed that incidence and severity of powdery mildew significantly negative relationship with morning relative humidity (r = -0.631; p<0.05 and r = -0.721; p<0.01) and average relative humidity (r = -0.766 and r = -0.787; p<0.01). Temperature (maximum and average) and evaporation showed positive relationship with incidence and severity of powdery mildew. Further, stepwise linear regression model indicated that average relative humidity as single predictor independent variable had the strongest relationship disease incidence and severity, which explained 59 percent disease incidence and 62 percent for disease severity variability. This forewarning model can be useful for efficient management of powdery mildew disease of mango and as well as agro advisory services to farmers.

Genetic combining, heterosis analysis for horticultural traits in tomato (Solanum lycopersicum L.) using ToLCV-resistant lines and molecular validation of Ty genes

AbstractTomato is a pivotal vegetable crop worldwide concerning human nutrition, economy and in service to biotechnology. Tomato leaf curl virus (ToLCV) is a begomovirus transmitted through the whitefly (Bemisia tabaci) and is responsible for severe losses in tomato production. In this context, the current investigation was carried out to determine heterotic combiners with high yield, resistance to ToLCV and mode of gene action for economically important traits. For this, 11 prescreened inbred lines were crossed in a half diallel fashion to generate 55 F1 hybrids. The 55 crosses with 11 parents and commercial checks were evaluated for different horticultural traits and resistance to ToLCV. The molecular validation with SCAR markers TG0302 and SCAR1 confirmed the presence of ToLCV-resistant genes in parents and their crosses. The hybrid IIHR-2902 × IIHR-2852 showed the presence of both Ty-2 and Ty-3 alleles in the homozygous state. The estimation of σSCA2 and σGCA2 was significant. It also indicated that the genetic control of target traits was under additive and non-additive gene effects. The values of σA/D2 along with σGCA2/σSCA2 found to be less than unity indicates the preponderance of non-additive gene action in the expression of the studied traits except for percent disease incidence. The parental line IIHR-2919 was the best combiner for fruit and yield traits. The cross combinations IIHR-2913 × IIHR-2898 exhibited significantly higher economic heterosis for yield along with the presence of Ty-2 and Ty-3 genes. The study paves the way for breeding high yielding and ToLCV-resistant hybrids in tomato.

Essential Oil of Myrtus communis L. effects In Vitro and In Vivo Evaluation against Chickpea Blight (Ascochyta rabiei) Disease

In this study, (Myrtus communis L.) was explored in vitro and in vivo for controlling blight disease using two chickpea genotypes ILC 3279, INRA 199 and a local cultivar Bouazza. Blight caused by Ascochyta rabiei Pass. Lab. is major disease affecting chickpea production. To control this disease, chemical harmful fungicides are used hence, developing natural plant protection products as an alternative has become important regarding the environmental impact. The effect of essential oil (EO) extracted from myrtle leaves by hydrodistillation was evaluated on the growth of Ascochyta rabiei Pass. Lab. mycelium, by dilution method using chickpea culture medium added with 0, 200, 300, 500 and 1000 ppm. The radial growth of A. rabiei Pass.Lab. was inhibited at 40.9, 68.18 and 96.69% with 200, 300 and 500 ppm respectively. Myrtle essential oil used at 1000 ppm inhibited the fungus growth completely (100%). In vitro EO efficacy was investigated using detached leaflets method inoculated with 5 µl pathogen spore solution of 106 spores / ml concentration. Efficacy was investigated using 750 ppm EO solution. Disease (DS) Severity and disease incidence (DI) on detached leaflets were determined. Highest disease incidence was observed on Bouazza (100%) followed by ILC 3279 (84.28%) and INRA 199 (17.5%). Myrtle essential oil showed an efficacy in all cases and decreased significantly disease incidence for Bouazza, ILC 3279 and INRA 199 to 63.33, 56.66 and 16% respectively. Disease severity showed the same profile, Bouazza noted the highest rate followed by ILC 3279 and INRA 199 with 60, 40 and 21% respectively and EO showed a significant efficacy and reduced these disease severity rates to 52 32 and 18 %. The bioassay conducted in vivo under greenhouse conditions with plants including a negative control with any treatment and two other batches inoculated by hand held sprayer, a spore solution with a concentration of 106 spores/ ml and treated or not with myrtle EO. Disease incidence percentage (DIP) decreased significantly under common myrtle EO compared to control in INRA 199 and ILC 3279 for severity percent index (SPI) no significant difference was observed for all genotypes under Myrtus communis L. essential oil treatment effect. This study showed Myrtus communis L. essential oil efficacy on chickpea blight disease in vitro on fungal radial growth and in vivo either on deatached leaflets or whole plants under greenhouse condition. This natural product reduced significantly blight disease incidence and severity. And to control disease, myrtle essential oil extraction as fungicide is a promising alternative against this disease.

Effect of Different Botanical Extracts and Organic Compound in The Management of Leaf Spot Disease of Strawberry (Fragaria ananassa Duch.) Caused by Pestalotia longisetula under Field Condition

A field experiment was carried out using sweet sensation variety of strawberry to check the efficacy of different botanical extracts and organic compounds to manage leaf spot disease. The study was done using ten treatments viz; ginger (T1), turmeric (T2), garlic (T3), ginger + turmeric + garlic (T4), cow urine (T5), cow urine+ ginger + turmeric + garlic (T6), compost tea (T7), compost tea+ ginger+ turmeric+ garlic (T8), SAAF (mancozeb 63 % + carbendazim 12%) (T9) and control (T10), which was replicated thrice. The parameter observed during experiment were plant height, leaf number, disease leaves, stem lesions, yield, percent disease incidence, disease severity percent and percent disease control. At 75 days of transplantation, the highest plant height, leaf number (24.60) and yield (1391.67 gm/plot) were observed in treatment compost tea (18.14 cm), cow urine+ ginger+ turmeric+ garlic and garlic respectively and lowest in treatment control (16.19 cm, 23.27 & 566.67 gm/plot). The disease leaves and stem lesions were observed highest in treatment control (3.40&3.23) and lowest in treatments garlic (3.0), and cow urine+ ginger+ turmeric+ garlic (1.83) respectively at 75 days after transplantation. Moreover, the highest percent disease incidence and disease severity percent were observed highest in treatments control (28.94% & 84.81%) and percent disease control in treatment garlic (42.36%) at 75 days of transplantation. Therefore, it is suggested to use garlic extracts as a measure to control leaf spot disease of strawberry. Int. J. Appl. Sci. Biotechnol. Vol 9(3): 193-202.

Evaluation of plant extracts for the management of Cowpea anthracnose disease caused by Colletotrichum lindemuthianum

The fungus Colletotrichum lindemuthianum is both seed and soil borne which is the causative of cowpea anthracnose. This causes a significant loss of the crop and becoming a major hindrance in its bumper productivity in all countries where such crop is grown. In order to find out an environment friendly, sustainable control protocol, experiments were conducted by taking eight different plant extracts against the pathogen. The extracts were applied to the plant samples after the 25th day of germination in the field. Application of neem followed by ginger, onion, garlic and tulsi extracts effectively reduce the percent disease incidence by 90%, 85%, 82%, 79% and 76%, respectively. Similarly, the percent green pod yield increased by 134,127, 114, 93 and 84, respectively over control as well as the cost-benefit ratio which can be recommended to the farming community.

Screening of wild okra (Abelmoschus moschatus) germplasm for okra yellow vein mosaic disease resistance in India

Okra yellow vein mosaic disease (OYVMD) is a major viral disease of okra crop caused by Okra yellow vein mosaic virus (OYVMV). The disease is responsible for direct yield loss in terms of both quantity and quality of capsules (fruits). Initially, DNA-A of coat protein, intergenic region and partial rep protein sequences were determined using OY2395F/OY680R specific primer and the amplified 1.2 Kb band product showed presence of OYVMV. Two years field screening of wild okra accessions (Abelmoschus moschatus ssp. moschatus) carried out during kharif 2017 and 2019 against OYVMD in agro-ecological conditions of New Delhi. Among seventy six (76) wild okra accessions 10 accessions, viz. EC360586, EC360794, EC360830, EC360900, EC359730, EC359836, EC359870, EC360351, EC361171 and EC361111 exhibited resistant (R) response in kharif 2017. While in 2019, out of these 10 promising accessions, four accessions, viz. EC360794, EC360586, EC360830 and EC361171 further showed R response. Rest of the tested lines showed either moderately resistant (MR) or susceptible (S) response. Average percent disease incidence (PDI) value was 19.51% and range value was 4.46 to 64.06% for the first year of field screening. Whereas the recorded average PDI were 21.77% with the range value of 4.36 to 67.33% in the second year. For both the years, out of 76 accessions, four accessions, viz. EC360794, EC360586, EC360830 and EC361171 were found promising and exhibited R response consistently. These promising lines could be utilized in breeding programmes for development of varieties resistant to OYVMV.

Prevalence and Incidence of Cassava (Manihot esculenta) Brown Leaf Spot Disease Caused by Cercospora heningsii in Macuata Province, Vanua Levu, Fiji

Cassava (Manihot esculenta Crantz) is a crop of many values in the tropical and subtropical regions of the globe. In Fiji, cassava is cultivated on vast acres of land but, the yield obtained is relatively lower because of many constraints, including the prevalence of diseases caused by the different pathogens. Among various pathogens responsible for a lower yield, the cassava brown leaf spot disease caused by Cercospora heningsii is responsible for causing enormous annual losses of cassava in tropical and subtropical regions. Because there is very little information regarding the association of the brown leaf spot disease and cassava in the country, the present study using survey as research instrument endeavors to determine the disease incidence and prevalence of brown leaf spot disease in the cassava fields of three villages (Mani Road, Boca, and Anuve) in the Bulileka area of the Macauta province in Vanua Levu, Fiji. The study found that brown leaf spot disease prevailed (100%) in all three villages. The percentage of disease incidence ranged from 36.4% to 42.9%. The maximum incidence (42.9%) of cassava brown leaf spot disease was found in Anuve village, followed by Mani Road village (38.2%), with the lowest disease incidence recorded for Boca village (36.4%).

Mycoparasitic nature of Egyptian Trichoderma isolates and their impact on suppression Fusarium wilt of tomato

BackgroundPlant disease administration is difficult due to the soil-borne nature of the phytopathogens. Biological control of plant disease is a safe mode to avoid the problems related to fungal diseases that affect crops productivity.ResultsTwenty-three Trichoderma isolates were isolated from soil, surrounding healthy tomato roots from different regions in the Egyptian Governorate of Menoufia. Using a dual culture method to test the efficiency of Trichoderma isolates, the most effective isolate identified as Trichoderma atrovirde with percentage inhibition against Fusarium oxysporum f. sp. lycopersici (92.11%) and scanning electron microscope examination documented the mycoparasitic nature of T. atrovirde to F. oxysporum. Treatments with 10% filtrate T. atrovirde improved the growth aspects of tomato plants than the control plants or infected only, as well as the increase in phenol content (15.09 ug. g-1dry weight) and decreased disease incidence percentage (8%) than the plants infected only (60%).ConclusionsThis study clearly demonstrated that T. atrovirde had a significant inhibition against F. oxysporum. Greenhouse assays displayed the protective role of T. atrovirde inoculation directly against pathogen or indirectly related to the defense mechanism in the plant. So, this study recommends using T. atrovirde for biological control of wilt disease in tomato plants.

Resistance of several wheat varieties grown at the medium altitude of East Lombok to leaf blight disease

Wheat is a subtropical plant that can only be cultivated in tropical highlands of Indonesia at an altitude of >800 m above sea level. When planted at a lower altitude, the wheat need to adapt to different climate conditions (the adaption getting a lot harder due to climate change issues), especially to the disease they will face in warmer conditions. The research aimed to determine the resistance of several wheat varieties grown at medium altitude to leaf blight disease had been conducted in East Lombok, Indonesia. The research applied a Randomized Completely Block Design (RCBD) with 12 wheat varieties, namely: Nias, Dewata, Axe, Gladius, Correll, Cobra, Espada, Scout, Mace, Sunstate, Janz, and Westonia. The incidence of natural infection of Bipolaris sorokiniana, the causal agent of leaf blight disease of wheat, was observed weekly. The wheat yield was also measured after harvest. The results showed that the highest average percentage of disease incidence (35.97%) was found in the Axe variety which is categorized as susceptible to leaf blight disease, while the lowest (11.37%) was found in the Janz variety which is categorized as resistant variety. The highest yield of wheat (3.16 ton/ha) was found in the Nias variety with the disease incidence of 13.21%, and the lowest (0.68 ton/ha) was found in the Cobra variety with the disease incidence of 20.96%.

Screening of Mungbean (Vignaradiata L. Wilczek) Genotypes for Resistance to Mungbean Yellow Mosaic Virus under Field Condition

Greengram [Vignaradiata(L.) Wilczek] is an economically important grain legume crop next to chickpea, pigeon pea and urad gram. Among the biotic factors, Mungbean Yellow Mosaic Virus (MYMV) is reported to be the most destructive viral diseases, which may reduce the seed quality as well as the yield losses up to 100 per cent. It is transmitted through whitefly (Bemisiatabaci) in a persistent manner throughout Asia, including India. A set of forty-two diverse mungbean genotypes were sown in two replications using a Randomized Block Desigh (RBD) during the summer season of 2015. The infector row method was adopted to evaluate a set of mungbean genotypes to know the difference in the level of resistance against MYMV infection under field condition during summer, 2015. Percent Disease Incidence (PDI) was calculated at 30 DAS and 50 DAS respectively. It varied from 2.18 to 64.77% and 5.38 to 76.87% at 30 DAS and 50 DAS respectively in summer, 2015. On the basis of disease severity recorded, the mungbean genotypes were classified in to five disease infection categories. Out of the forty-two mungbean genotypes, thirteen genotypes viz., Pusa 0672, IPM 205-7, HUM 8, KM 2245, IPM-2-03, ML 1464, KM 2241, PDM-139, TARM-1, HUM 26, Meha, HUM 16 and IPM 409-4 were found to be resistant and may provide the source of resistance against MYMV to develop mapping population for molecular breeding, development of molecular markers, QTL identification for MYMV resistance, as well as development of MYMV resistant varieties.

Multitudinous Potential of Trichoderma Species in Imparting Resistance Against F. oxysporum f. sp. cucumerinum and Meloidogyne incognita Disease Complex

Trichoderma spp. effectively inhibited mycelial growth of Fusarium oxysporum f. sp. cucumerinum F1, egg hatchability and juvenile mobility of M. incognita. Field emission scanning electron microscope (FESEM) studies revealed that Trichoderma koningiopsis TRI 41 effectively hyperparasitized and lysed the mycelium of F. oxysporum f. sp. cucumerinum F1, egg mass and individual eggs of root-knot nematode. Further, GC–MS profiling of the agar plugs, excised from the point of hyperparasitism by TRI 41, from the dual plate assay revealed a shift in the non-volatile organic compounds (NVOC) profile. In vitro, TRI 41 produced maximum indole acetic acid (IAA) (15.25 µg/ml) and gibberellic acid (GA) (10.40 µg/ml) in PDB. T. koningiopsis TRI 41 increased the root length (28.74 cm), shoot length (14.64 cm) and stem girth (1.76 cm) of cucumber seedlings to the maximum in vermicompost:soil:sand medium. Furthermore, TRI 41 influenced the root architecture of cucumber plants and altered the root exudate pattern in the rhizosphere of 35-day-old cucumber seedlings. Various non-volatile organic compounds with antifungal and antibacterial activity were detected in the rhizosphere. Under field conditions, seed treatment with the consortia of the isolates, including T. koningiopsis TRI 41, Trichoderma asperellum TRI 15 and Trichoderma asperelloides TNAU Tad 1 @ 1 ml/kg of seed (0.1%) applied as soil drenching (100 ml of gel formulation in 100 L of water over 1000 m2 area of polyhouse), indicated that the incidence of fungal nematode complex was reduced to 13.45% with 80.0 fruits/plant with a mean yield of 15.01 t/1000m2. For instance, the untreated control was reported with 41.32 percent disease incidence, 52.0 fruits/plant with a mean yield of 10.20 t/1000m2.

NURSERY AND FIELD EVALUATION OF STREPTOMYCES NIGROGRISEOLUS GANOSA1 TO CONTROL BASAL STEM ROT IN OIL PALM SEEDLINGS

Basal stem rot (BSR) disease caused by Ganoderma species is a threat to the oil palm industry. In our initial study, rhizosphere actinomycetes identified as Streptomyces nigrogriseolus GanoSA1 (Streptomyces GanoSA1) possess competent biological control activity in the growth of Ganoderma in vitro. This study was carried out to evaluate whether Streptomyces GanoSA1 formulated in the vermiculite-bio charcoal powder can reduce disease incidence caused by G. boninense PER71 and promote oil palm growth through nursery and field trial. Mixing of Streptomyces GanoSA1 powder at 108 CFU (colony-forming unit) per gramme in soil resulted in the strain establishment in the applied soil and increased oil palm seedlings height with no observed adverse effect on seedlings growth. The seedlings treated with the powder formulation resulted in a reduced percentage of disease incidence (DI, %) by 51.1 per cent and disease severity index (DSI, %) by 35.0 per cent compared to untreated seedlings and seedlings inoculated with G. boninense PER71 alone (93.3% DI and 75.83 % DSI, respectively). The field trial indicated that, after 36 months of planting, only 6.6 per cent of oil palm treated with the Streptomyces GanoSA1 powder showed symptoms of BSR disease and death due to Ganoderma infection compared to the untreated oil palm at 75.0 per cent. These trials highlight the potential of the Streptomyces GanoSA1 powder to reduce BSR disease in oil palm and promote oil palm growth. Keywords: Streptomyces, Ganoderma, artificial inoculation, seedling baiting technique.

Pathogenicity, Host Range and Influence of Temperature, Humidity and pH Levels on the Growth of Fusarium oxysporum f.sp. lentis

Background: Lentil is a vital nutritional source of protein in several parts of the world including India. The crop is susceptible to wilt which is a devastating soil-borne disease induced by the fungus Fusarium oxysporum f. sp. lentis. Insight of the potential threat Fusarium wilt can pose to lentils, a present study done on pathogenicity, host range and influence of temperature, humidity and pH levels on the growth of F. oxysporum f. sp. lentis.Methods: Ten isolates FOL-01 to FOL-10 of F. oxysporum f. sp. lentis (Fol) were isolated from wilted lentil plants that collected from different major lentil growing parts of Rajasthan. During 2017-18 a pathogenicity test was tested in pot house condition by seed and soil inoculation techniques for all isolates and epidomological factors evaluated in vitro conditions.Result: Results indicated that the Fol isolates represent a single race but differ in their aggressiveness on the susceptible cultivar L9-12. Pathogenicity test revealed clearly that Fol was associated with wilt symptoms and were pathogenic to lentil plants. A maximum percent disease incidence of 70.00 was showed by isolate FOL-02 in soil inoculation technique. In the morphological and cultural characterization, all the ten isolates showed various character in conidial frequency, colony color and growth pattern. Twenty plant species were tested to know the host range of Fol, out of these lentil, chickpea and pea show positive reaction with the pathogen. The influence of temperature, relative humidity and pH on the growth and sporulation of Fol was studied under in vitro conditions. Maximum mycelial growth and sporulation of the Fol were observed at 30°C, 6.0 pH and 60% relative humidity.