S. Sriram ¹, M. J. Savitha ¹, B. Ramanujam ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, H. A. Farm Post, Hebbal, Bellary Road, Hebbal, Bangalore, 560 024, Karnataka, IN

Abstract

Coconut coir dust, commercially available as coco-peat, is used in raising the seedlings of vegetable crops in tropical countries. Coir-pith and other derivates of coconut husk have been well recognized as substrates for the multiplication of Trichoderma spp. and commercial nurseries use coco-peat for raising the seedlings. In the present study, coco-peat enriched with Trichoderma harzianum was used for raising tomato and chilli seedlings to test the effect of the same on managing wilt caused by Fusarium oxysporum f. sp. lycopersici in tomato and damping off and ischolar_main rot caused by Phytophthora capsici in chillies in nurseries. The enrichment with T. harzianum, resulted in reduced wilt incidence (5-7.5%) compared to control (38.75%) in tomato with increased plant growth parameters. Though germination was reduced compared to control (without pathogen), there was reduction in P. capsici infection in chillies by up to 50% compared to coco-peat without Trichoderma enrichment. The use of coco-peat enriched with T. harzianum can be adopted by commercial nurseries for better plant growth and reduced incidence of tomato wilt and chilli ischolar_main rot while raising disease free and healthy seedlings.

Keywords

Trichoderma spp., Coco-Peat, Fusarium oxysproum f. sp. lycopersici, Phytophthora capsici, Tomato, Chilli, Commercial Nurseries.

Full Text

   

G. Sivakumar ¹, R. Rangeshwaran ¹, S. Sriram ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, H.A. Farm Post, Hebbal, Bellary Road, Bangalore, 560024, Karnataka, IN

Abstract

Among 100 isolates of Bacillus spp. screened in vitro against Ralstonia solanacearum that causes bacterial wilt of brinjal, ten were found inhibitory to R. solanacearum. Bacillus megaterium isolate NBAII 63 was highly inhibitory with 29.20 mm of inhibition zone against R. solanacearum as compared to the other nine strains of Bacillus. Six of them were identified by 16S rDNA analysis. The bioefficacy of talc formulation of B. megaterium was evaluated under greenhouse for plant growth promotion and suppression of bacterial wilt in brinjal. The bacterial wilt was effectively managed by B. megaterium through different methods of applications. A combination of four methods (seed treatment + soil application + seedling ischolar_main dip + foliar spray) was the most effective. Maximum ischolar_main length (23.42 cm), shoot length (65.21 cm), fresh weight (40.39 g), dry weight (10.33 g) and highest wilt reduction (50.54%) was recorded in the combination method. Among single application methods, seed treatment was effective exhibiting 41% reduction of bacterial wilt followed by soil application which gave 36% wilt reduction. The bacterial wilt reduction in chemical control (streptomycin sulphate) was 71%. Good growth of the brinjal plants was recorded due to application of B. megaterium. Highest rhizosphere population of 67.0 × 10⁶ cfu/g was recorded in brinjal at 40 days after transplanting when the antagonist was applied by combining the different application methods.

Keywords

Bacillus Spp, Ralstonia solanacearum, Bioefficacy, Talc Formulation, Brinjal.

Full Text

   

R. Rangeshwaran ¹, N. V. Vajid ¹, B. Ramanujam ¹, S. Sriram ¹, T. V. Bhaskaran ¹, Satendar Kumar ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, Post Bag No. 2491, H. A. Farm Post, Hebbal, Bellary Road, Bangalore 560 024, Karnataka, IN

Abstract

Studies were carried out to evaluate the effect of adding nutrient additives to talc based formulations on the shelf life of bacteria stored under room temperature. Two organisms namely, Pseudomonas fluorescens (PDBCAB2) and Bacillus sp. (MTCC6534 - chickpea endophyte), a spore forming bacterium, were tested. A gradual increase in P. fluorescens population up to 90 days was observed in almost all the treatments that were amended with nutrients. At 90 days highest population of log 10.38 cfu g⁻¹ was noticed in talc amended with 2 per cent tryptone and glycerol. Decline in the population was observed from 90 days onwards and was rapid from 150 days onwards. At 240 days highest count of log 1 x 10^4.2 cfu g⁻¹ was obtained with formulations amended with 2% tryptone and 2% glycerol and the results indicated that 2% peptone or 2% tryptone supplemented with 2% glycerol helped P. fluorescens in its better survival. The spore forming Bacillus sp. survived well throughout the study period. At 240 days all talc formulations amended with nutrient sources showed a population of log 9.0 cfu g⁻¹ or above and the population declined to below log 7.0 cfu g⁻¹ only in non amended treatments. Slow decline started from 240 days but high cfu of log 9.30 to 9.38 g⁻¹ were noticed in yeast extract or tryptone treated treatments. Hence talc formulations that had yeast extract or tryptone supplemented with glycerol enhanced shelf life of Bacillus spp.

Keywords

Pseudomonas fluorescens, Bacillus sp, Powder Based Formulation, Talc, Shelf Life, Gram Positive, Gram Negative.

Full Text

   

N. Arulmani ¹, S. Sriram ², R. Rangeshwaran ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, P.B. No. 2941, H.A. Farm Post, Bellary Road, Hebbal, Bangalore 560 024, IN
2 Division of Plant Pathology, Indian Institute of Horticultural Research, Bangalore 560 089, IN

Abstract

Diacetylphloroglucinol (DAPG) producing isolates of pseudomonads were screened against bacterial wilt in brinjal caused by Ralstonia solanacearum under greenhouse conditions. Thirty Pseudomonas isolates were obtained from the culture collection of NBAII, Bangalore that include seven isolates of Pseudomonas putida (CK8C, CK24E, Pf4K, RPF9, RPF13, OTN5E2, GR1ARS1), one P. mosselli (CK24C) isolate, three isolates of P. fluorescens (GR3ARS3, Pf-DWD, CHAO), three isolates of P. plecoglossicida (BA11D1, BA16-2, BA3-D1) and sixteen isolates of P. aeruginosa (CK13C, CK19E, AFP3, AFP4, AFP6, RFP7, OTN8, AFP9, AFP8, PDB8, PDB1, AFP7, AFP5, AFP13, ND4-IARIB, RPF8). Bacterial wilt susceptible brinjal variety MEBH- 9 was used in the screening. The brinjal seedlings were dipped in Pseudomonas suspension for five minutes before transplantation and plants were observed for wilt symptoms like stunted growth, drooping of leaves, loss of rigidity and eventually death of the plant. Four weeks later, the plants were upischolar_mained and length and weight of both ischolar_mains and shoots were recorded. The highest percentage of wilt disease reduction was observed in seedlings treated with P. plecoglossicida BA11D1 (95.8%), P. putida CK24E (62.5%) and P. plecoglossicida BA3D1 (41.7%). Average shoot length, ischolar_main length and shoot weight, ischolar_main weight were comparatively lesser in most of the pseudomonads treated plants than the control plants.

Keywords

Ralstonia solanacearum, Bacterial Wilt, Plant Growth Promotion, Pseudomonads, Diacetylphloroglucinol.

Full Text

   

S. Sriram ¹, M. J. Savitha ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, Post Bag No. 249, H. A. Farm Post, Hebbal, Bellary Road, Bangalore 560 024, Karnataka, IN

Abstract

Traditionally serial dilution method is used for the enumeration of viable propagules in a microbial formulation. Conidia of some fungal agents like Trichoderma spp. are hydrophobic in nature. They repel water and are not dispersed uniformly in water. To enhance uniform distribution, dispersing agents like Tween 20 have to be used. In many articles in the published literature, high CFUs (>10¹¹ CFUs g^-1) have been either been claimed or reported to be present in formulations. Further considering the volume (4/3 × 3.14 × r³) occupied by each conidium (minimum 2 micron diameter), realistically we cannot expect high Colony Forming Units (CFUs) reported or claimed in many research papers. In the present report an attempt was made to estimate the possible 'number of conidia per cc' and 'number of conidia per g' of Trichoderma harzianum spores (NBAII Th10-MTCC 5584). The results showed that even at higher dilutions (>10^-18 to 10^-20) colonies of Trichoderma appeared on plates which is not theoretically possible. It is proposed that while enumerating the viable propagules in a formulation the serial dilution has to be done with Tween 20 and the tips should be changed for each dilution without fail. The dilution should be restricted to 10⁹ or 10¹⁰. The limitations of the serial dilution beyond 10¹⁰ and precautions to be taken are discussed.

Keywords

Trichoderma spp., Formulation, Serial Dilution, Enumeration, Viability.

Full Text

   

B. N. Hemalatha ¹, T. Venkatesan ¹, S. K. Jalali ¹, S. Sriram ¹, B. Reetha ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, H.A. Farm Post, Hebbal, Bangalore-560024, IN

Abstract

Resident microflora of alimentary canal and fat bodies associated with eleven field collected Chrysoperla zastrowi sillemi (Esben-Petersen) adult females were characterized and their possible role in influencing the fecundity was studied. The isolated yeasts varied among different populations of the predator. Culturable yeasts viz., Wickerhamomyces anomalus, Pichia anomala, Candida blankii, C. apicola, C. pimensis, Torulaspora delbrueckii, Zygosaccharomyces rouxii and Kodamea ohmeri were isolated from gut, diverticulum and fat bodies of the adult females and characterized by biochemical and molecular tools. The yeast isolate of T. delbrueckii in combination with honey and castor pollen grains were found to increase the fecundity of the adult females as compared to those that were reared on honey and pollen in different generations.

Keywords

Chrysoperla Zastrowi Sillemi, Yeast, Molecular Characterization, Fecundity.

Full Text

   

S. Sriram ¹, S. B. Manasa ², M. J. Savitha ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, Post Bag No. 2491, H. A. Farm Post, Bangalore 560024, Karnataka, IN
2 Department of Plant Science, School of Life Sciences, Bharathidasan University, Tiruchirapalli 620024, Tamil Nadu, IN

Abstract

Eleven isolates of Trichoderma harzianum were screened for their potential to induce systemic resistance against Phytophthora capsici in red pepper plants. The effect of talc formulations of these eleven isolates on induction of glucanase activity and phenol content was studied. There was a significant increase in glucanase activity in plants treated with Th8 and Th1 (94 and 90 μg glucose released min^-1 g^-1) compared to control (77 μg). Similarly phenol content also increased in plants treated with Th4, Th7 and Th10 (48-59 μg g-1) compared to control (34 μg g^-1). Cell wall glucan elicitors were extracted from T. harzianum isolate Th10 that had been reported earlier as an efficient biocontrol agent. Treatment with elicitor preparations also induced high glucanase activity (40 μg glucose released min-1 g-1) and increased phenol content (42 μg g^-1) compared to control where the glucanase activity was 33 μg glucose released min^-1 g^-1 while phenol content was 27 μg g^-1. Similarly the elicitor treatment as seedling dip reduced P. capsici infection to 23% compared to control (93%). The potential use of ISR eliciting isolates in the biocontrol of P. capsici in red pepper is discussed.

Keywords

Cell Wall Glucan Elicitor, Induced Systemic Resistance (ISR), Phytophthora capsici, Red Pepper, Trichoderma harzianum.

Full Text

   

Suresh Patil ¹, S. Sriram ¹, M. J. Savitha ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, Post Bag No, 2491, H.a. Farm Post, Bellary Road, Hebbal, Bangalore 560024, Karnataka, IN

Abstract

Fusarium spp. isolated from rhizosphere soils of tomato from Karnataka, Tamil Nadu and Gujarat states of India were tested for their pathogenicity. Among these isolates, six were found non-pathogenic to tomato, red gram, bengal gram, groundnut, red pepper, water melon, castor and banana. These non-pathogenic isolates protected tomato plants when co-inoculated with pathogen isolate under pot culture conditions. Treatment with non-pathogenic Fusarium isolates improved the plant growth parameters (length and weight of ischolar_main and shoot). These non-pathogenic Fusarium isolates can be exploited for the biocontrol of wilt disease.

Keywords

Biocontrol, Non-pathogenic Isolates, Fusarium Spp., Tomato, Wilt.

Full Text

   

S. Sriram ¹, R. S. Misra ²

Affiliations
1 Regional Centre of Central Tuber Crops Research Institute, Dumduma PO, Bhubaneswar - 751019, Orissa, IS
2 Regional Centre of Central Tuber Crops Research Institute, Dumduma PO, Bhubaneswar - 751019, Orissa, IN

Abstract

Effect of seed treatment, soil application and foliar spray of rhizobacterial cultures that were isolated from Colocasia esculenta on Phytophthora blight was studied under polyhouse and field conditions. Under polyhouse conditions, when applied as seed tuber treatment, the antagonistic rhizobactcrial cultures S1B3, S11B4, S13B5 and S23BS reduced the Phytophthora blight disease severity. In these treatments there was no disease incidence compared to control where the disease severity was 2.92 on a 0-5 disease rating scale. In soil application, when rhizobactcrial cultures S4BS, S13B5 and S23BS were used, the disease incidence was nil compared to control where disease severity was 2.83 on a 0-5 disease rating scale. Foliar application with S1B4 and S11B3 reduced the disease severity to 0-0.33 rating compared to 2.66 in control. Under field conditions, tuber treatment with S1 B3, soil application of S13B5 or foliar application with S1B4 and S11B3 reduced the disease severity and increased the yield compared to untreated pathogen-inoculated control plants. Seed treatment with S1B3 resulted in tuber yield of 255g/plant compared to 95.42g in control. Soil application with S13B5 resulted in 232.65g/plant, while in foliar application with S1B4 or S11B3, yield were 274g and 605g per plant, respectively. These treatments promoted the plant growth also. These treatments were tested in the field and it was found that application of bacteria in combination (seed treatment, soil treatment and foliar spray) helped in reducing the leaf area damaged due to blight by 41% during the first peak of the disease spread and by 28% during the second peak of the disease spread. Rhizobacteria treatment also helped in reducing the storage losses. The storage loss of tubers harvested from rhizobacteria treated plots ranged from 4.14 to 21.24% compared to 26.02 and 21.78% in fungicide treated and control plots, respectively, resulting in 18 to 36% increased yield in the field trials.

Keywords

Biological Control, Colocasia esculenta, Phytophthora colocasiae, Rhizobacteria.

Full Text

   

S. K. Jalali ¹, S. Sriram ², T. Venkatesan ¹, R. P. More ¹, Omprakash Navik ¹, Y. Lalitha ¹, Rakshit Ojha ¹

Affiliations
1 ICAR-National Bureau of Agricultural Insect Resources, Post Bag No. 2491, H. A. Farm Post, Bellary Road, Hebbal, Bangalore – 24, Karnataka, IN
2 ICAR-Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore – 89, Karnataka, IN

Abstract

Host-insect and host-plant associated differentiation of genetically divergent microbiota were recorded from economically important egg parasitoid collected from 26 locations in India, Trichogramma chilonis constituted 86.8% of the populations collected. It was recorded from 14 host-insects, 14 different crops and weed plants from 12 states. Nine species of yeast were recorded from parasitoid from 5 host-insects with Wickerhamomyces anamalus was isolated from 36.4% samples and highest numbers were recorded from parasitoid collected on sugarcane. Bacillus cereus, Pseudomonas sp. and Stenotrophomonas maltophilia from T. chilonis constitute 64.3% of bacterial diversity based on their 16S rDNA sequences. For taxonomic identification using 16s rDNA and ITS sequences, we performed taxonomic classification of total 33 ITS isolates against UNITE Fungal ITS database and assigned taxonomy hierarchy to the sequences. Also, a total of 13 isolates 16s rDNA sequences were taxonomically assigned against RDP 16s rDNA database using RDP Naive Bayesian rRNA Classifier Version 2.1. Most of the species are correctly identified in the respective species members with high confidence threshold value support.

Keywords

Egg Parasitoid, Evolutionary Relationship, Host-Insects, Host-Plants, Microbiota.

Full Text