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R. K. Srivastava ¹, R. K. Singh ¹, R. D. Prasad ²

Affiliations
1 Department of Plant Pathology, Crop Research Station, Bahraich, 271801, Uttar Pradesh, IN
2 Oilseeds Research, Rajendranagar, Hyderabad, 500030, Andhra Pradesh, IN

Abstract

Isolates of Trichoderma viride and T. harzianum were tested for their myco-parasitic ability and relative antagonistic effect that showed all the Trichoderma isolates inhibited significantly the growth of the pathogen and it ranged from 62.73% (T. viride 1) to 45.37% (T. viride PDBC TV 23). Germination per cent ranged from 78.8 (T. viride 3) to 98.9 (T. viride PDBC TV 23) when treated with bio-agents, whereas in pathogen check it was only 73.3%. Maximum vigor index (547.3) was recorded in T. viride (PDBC TV 23), whereas in pathogen check it was 84.7 only. Fungicide treatment exhibited almost equal disease incidence and in pathogen check, it was as high as 68.9%, while minimum (16.7%) plant mortality was recorded in seeds treated with T. viride 1. In fungicidal treatment 33% plant mortality was recorded while in pathogen check it was highest (46.7%). The results obtained clearly indicated that the efficacy of different isolates of the same species also showed variation when tested against the same pathogen. Therefore, it may be concluded that before application in the field the potentiality of every strain of the bioagents should be tested against the target pathogen.

Keywords

Antagonist, Trichoderma Spp, Phytophthora capsici, Bell Pepper.

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M. Charitha Devi ¹, R. D. Prasad ²

Affiliations
1 Department of Virology, Sri Venkateswara University, Tirupati 517502, Andhra Pradesh, IN
2 Directorate of Oilseeds Research, Rajendranagar, Hyderabad 500030, Andhra Pradesh, IN

Abstract

The collor rot incidence in groundnut was reduced by the application of Trichoderma viride as seed treatment along with fungicides. In vitro studies of fungal and bacterial antagonists, viz., Trichoderma spp. and Pseudomonas fluorescens indicated that T. viride was more effective in inhibiting the pathogen A. niger. In pot culture experiment, the combined effect of seed treatment with T. viride and captan resulted in significant reduction of collor rot. Combination of antagonist and fungicide also improved the growth parameters like length of the plant, biomass and yield besides decreasing the disease incidence. Biointensive disease management of collar rot is not only effective but also economical.

Keywords

Aspergillus niger, Biocontrol Agents, Collar Rot, Fungicides and Groundnut.

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R. D. Prasad ¹, K. Anjani ¹

Affiliations
1 Directorate of Oilseeds Research, Rajendranagar, Hyderabad -500 030, IN

Abstract

In an integrated management approach against safflower wilt, Trichoderma species application to susceptible and moderately susceptible varieties of safflower was tried over two seasons in fusarial wilt affected plots. Though the disease incidence levels compared to a pathogen only check (96.7%) are significantly low in var. Nira with T. viride and T. harziaiium seed applications (44.5 and 50.9 % respectively), the disease incidence in general is very high in bioagent treatments since the variety Nira is highly susceptible. T. harzianum soil application in var. Al resulted in significantly low disease compared to pathogen check and fungicide treatments but comparable to soil application of bioagents over two seasons. In general, there was an increase in bioagents populations and reduction in Fusarium population in the rhizosphere. By adopting a moderately susceptible variety like Al in place of susceptible varieties of safflower and application of Trichoderma species either to the soil or on the seed the wilt disease in safflower can be managed more efficiently.

Keywords

Fusarium oxysporum f. sp. carthami, Safflower Wilt, Trichoderma Species.

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D. L. Rudresh ¹, M. K. Shivaprakash ¹, R. D. Prasad ²

Affiliations
1 Department of Agricultural Microbiology, University of Agricultural Sciences GKVK, Bangalore, 560065, Karnataka, IN
2 Directorate of Oilseeds Research, Rajendranagar, Hyderabad-500 030, IN

Abstract

Nine isolates of Trichoderma spp. were tested for their ability to inhibit soil borne fungal pathogens of chickpea viz. Rhizoctonia solani, Sciendum rolfsii, Fusarium oxysporum f. sp. ciceri under both in vitro and in vivo conditions. Laboratory evaluation of Trichoderma isolates by dual-culture test, inverted plate technique and poisoned food technique revealed Trichoderma harzianum-PDBCTH 10 to be more inhibitory against R. solani and S. rolfsii followed by J. viride-PDBCTV 32 and T. virens-PDBCTVs 12, whereas T. virens-PDBCTVs 12 was found to inhibit Fusarium oxysporum f. sp. ciceri to a greater extent than other isolates. Pot culture evaluations under greenhouse conditions using T. harzianum -PDBCTH 10, T. viride-PDBCTV 32 and T. virens -PDBCTVs 12 revealed T. harzianum-PDBCTH 10 to be an effective biological control agent against rhizoctonia ischolar_main rot and sclerotium collar rot whereas T. virens-PDBCTVs 12 was found effective against fusarium wilt. Further, in addition to biological control of soil borne fungal pathogens seed inoculation of Trichoderma spp. also found to increase growth and yield of chickpea (Cicer arietinum L.) under greenhouse conditions.

Keywords

Biological Control, Cicer arietinum, Fusarium oxysporum f. sp. Ciceri, Rhizoctonia solani, Sclerotium rolfsii, Trichoderma spp.

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C. Gopalakrishnan ¹, B. Ramanujam ¹, R. D. Prasad ¹, N. S. Rao ¹, R. J. Rabindra ¹

Affiliations
1 Project Directorate of Biological Control (ICAR) P.B. No. 2491, H.A. Farm Post, Bellary Road Bangalore 560024, Karnataka, IN

Abstract

Out of twelve Trichoderma isolates tested, cotton isolate T. viride (97) exhibited the fastest growth rate and strong antagonism against Rhizoctonia solani in vitro recording 56.2 per cent inhibition in dual culture. All the isolates tested enhanced cotton seed germination when treated with mycelial suspensions of bioagents in vivo. The disease incidence in bioagent treatments ranged between 14.8 to 32.4 per cent, while pathogen treatment recorded 82 per cent. Three isolates have recorded seedling vigour index above 2000, which was much better than fungicide treatment (1471) in blotter tests (Roll Towel Method). T. viride (32) recorded the maximum seed germination (86.4 per cent) and no incidence of post -emergence mortality under green house conditions. The seedling vigour index in bioagent treatments ranged between 1004 and 1866.

Keywords

Biocontrol, Cotton, Damping-off, Rhizoctonia solani, Trichoderma.

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C. Gopalakrishnan ¹, B. Ramanujam ¹, R. D. Prasad ¹, N. S. Rao ¹, R. J. Rabindra ¹

Affiliations
1 Project Directorate of Biological Control (ICAR) P.B. No. 2491, H.A. Farm Post, Bellary Road Bangalore 560024, Karnataka, IN

Abstract

Among four different levels of brewers' yeast tested, 3g/100 g of spent malt was found to be optimum for the growth of Trichoderma harzianum in solid-state fermentation. Spent malt brewers' yeast medium supported all the species namely, T. harzianum, T. viride and T. virens. T. harzianum recorded the highest number of viable propagules after twelve days of incubation. All the treatments recorded more number of viable propagules after twelve days of incubation than after seven days of incubation.

Keywords

Brewers' Yeast, Solid State, Spent Malt, Trichoderma harzianum.

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A. K. Patibanda ¹, R. D. Prasad ²

Affiliations
1 Acharya N. G. Ranga Agricultural University, Agricultural Research Station, Tandur 501 141, Ranga Reddy District, Andhra Pradesh, IN
2 Directorate of Oilseeds Research, Rajendranagar, Hyderabad 500 030, IN

Abstract

Four Triehodenna isolates were tested for in vitro their antagonistic potential against safflower wilt causing pathogens Fusarium oxysporllnl f. sp. earthami and Macrophomina phaseolilla. Trichoderma viride (PDBC TV 32) and T. harzianum (POne TH 10) were effective against both the pathogens. Trichoderma viride, isolated from the Fllsarium wilt sick plot in Tandur was effective only against M. phaseolin a, while F. oxysporllm f. sp. earlhami had inhihitory effect on sporulation of T. viride.

Keywords

Antagonism, Fusarium oxysporuni f. sp. cartlwmi, Macrophomina phuseolilla, Trichodermaspp.

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R. Rangeshwaran ¹, A. R. Wasnikar ², R. D. Prasad ¹, N. Anjula ¹, C. R. Sunanda ¹

Affiliations
1 Project Directorate of Biological Control (ICAR), Post Bag No. 2491, H. A. Farm Post, Bellary Road, Hebbal, Bangalore 560 024, Karnataka, IN
2 Department of Plant Pathology, Jawaharlal Nehru Krishi Vishwa Vidhyalaya, Jabalpur 482 004, M. P., IN

Abstract

Twentyfive endophytic bacteria were isolated from internal tissues of ischolar_main and stem portions of chickpea, sunflower, niger, chilli and capsicum plants. The endophytes were screened in dual culture on Potato Dextrose Agar (PDA) and Tryptic Soya Agar (TSA) against Fusarium oxysporum f. sp. ciceri, Fusarium udum, Rhizoctonia solani and Sclerotium rolfsii. Ten isolates exhibited inhibition of the pathogens. Maximum percent inhibition (37.93) of F. oxysporum f. sp. ciceri was obtained on PDA with B. subtilis (PDBCEN 3). On TSA percent inhibition was maximum (52.21) with isolate PDBCEN-7. Testing against F. udum in dual culture test revealed that Pseudomonas sp. (PDBCEN 8) showed maximum (40.45%) inhibition on PDA. Pseudomonas sp. (PDBCEN-2) was highly effective on TSA and showed maximum (56.9%) inhibition zone. Against R. solani, maximum inhibition (44.96%) was recorded with endophyte PDBCEN 7. On TSA all the ten endophytic bacteria were effective in restricting the growth of test fungus. Percent inhibition of S. rolfsii was maximum (40.93%) with Pseudomonas sp. (PDBCEN 6) on PDA. On TSA percent inhibition was maximum (46.73%) with P. fluorescens (PDBCEN 1). The endophytic isolates were able to promote better growth of chickpea but the vigour index varied between the isolates. We could not correlate high pathogen inhibition under in vitro with high vigour index.

Keywords

Biological Control, Endophytic Bacteria, Wilt Pathogens.

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R. D. Prasad ¹, R. Rangeshwaran ¹, C. P. Anuroop ¹, P. R. Phanikumar ¹

Affiliations
1 Project Directorate of Biological Control (ICAR), P. B. No. 2491, H. A. Farm Post, Hebbal, Bangalore 560 024, Karnataka, IN

Abstract

The conidia and chlamydospores of Trichoderma harzianum produced by solid state and liquid fermentation, respectively, were formulated as powder and tested for their comparative bioefficacy and shelf life. Both the propagules did not differ significantly in reducing ischolar_main rot incidence in chickpea caused by Rhizoctonia solani. Conidial formulation retained optimum amount of viable propagules (>10⁶ cfu/g) even after 180 days of storage at room temperature but in chlamydospore formulation, viable propagules reduced to less than 10⁶ by 150 days.

Keywords

Bioefficacy, Chlamydospores, Conidia, Formulation, Shelf Life, Trichoderma harzianum.

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R. K. Srivastava ¹, R. D. Prasad ², R. Rangeshwaran ², A. R. Wasnikar ³, S. P. Singh ², N. S. Rao ²

Affiliations
1 Crop Research Station, Narendra Deva University of Agriculture and Technology, Bahraich 271 801, U. P., IN
2 Project Directorate of Biological Control (ICAR), P. B. No. 2491, H. A. Farm Post, Hebbal, Bangalore 560 024, Karnataka, IN
3 Department of Plant Pathology, Jawaharlal Nehru Krishi Vishwa Vidhyalaya, Jabalpur 482 004, M. P., IN

Abstract

Eight Trichoderma isolates were tested for their bioefficacy against seed, ischolar_main and seedling rot incited by Rhizoctonia solani by adopting an in vivo test method (blotter test). Vigor index ranging from 169.5 to 2239.4 and disease incidence ranging between 10 to 86 percent were recorded in various treatments. All bioagents were graded based on disease grading key proposed for their rating. The clear differentiation of efficacy of various Trichoderma species against R. solani obtained with the in vivo bioefficacy test method adopted (blotter test) in the present study shows suitability of this method for routine screening of fungal biocontrol agents against seed and soil borne plant pathogens.

Keywords

Fungal Antagonists, in vivo Bioassay, Plant Pathogens.

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R. Rangeshwaran ¹, R. D. Prasad ¹, C. P. Anuroop ¹

Affiliations
1 Project Directorate of Biological Control (lCAR) Post Bag No.2491, H. A. Farm Post, Bellary Road Bangalore 560024, Karnataka, IN

Abstract

Talc based formulations of two antagonistic bacteria viz., Pseudomonas putida (PDBCAB 19) and P. fluorescens (PDBCAB 2) were evaluated against natural incidences of wilt and wet ischolar_main-rot of chickpea. Observations on rhizoclonia ischolar_main-rot incidence indicated that the disease was prevalent up to 60 days of plant growth whereas fusarial wilt was observed from 60 days. At 30th day. highest ischolar_main-rot incidence (10.8%) was observed in pathogen control plots and minimum was in fungicide treated plots (3.1 %). P. fluorescens (PDBCAB 2) treated plots also exhibited low ischolar_main-rot (4.4%). However, at day 60 lowest ischolar_main-rot incidence (5%) was recorded in P. fluorescens (PDBCAB 2) treated plots and highest ischolar_main-rot incidence (13.9%) was observed in pathogen control. Low ischolar_main-rot incidence (5.8%) was also noticed in P. putida (PDBCAB 19) treated plots. Fusarium wilt was lowest (3.3%) in P. putida (PDBCAB 19) treated and highest (13.3 %) in control plots at day 90. Combination of both P. fluorescens (PDBCAB 2) and P. putida (PDBCAB 19) exhibited suppression of ischolar_main-rot and wilt incidences by 5.8 and 7.5 per cent, respectively. Highest plant stand and seed yield was observed in P. fluorescens (PDBCAB 2) treated plots. There were no significant differences in the shoot and ischolar_main lengths among bioagent treatments, however, vigour index was highest in plots treated with a combination of P. fluorescens (PDBCAB 2) and P. putida (PDBCAB 19).

Keywords

Antagonistic Bacteria, Chickpea, Root-Rot, Wilt.

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R. Rangeshwaran ¹, R. D. Prasad ¹

Affiliations
1 Project Directorate of Biological Control (ICAR) Post Bag No. 2491, H. A. Farm Post, Bellary Road Hebbal, Bangalore 560024, Karnataka, IN

Abstract

Three hundred rhizospheric isolates of bacteria collected from different regions of Karnataka were screened for in vitro antagonism in dual culture on Tryptic Soya Agar (TSA) against five fungal pathogens viz., Botrytis cinerea, Macrophomina phaseolina, Sclerotium rolfsii, Rhizoctonia solani and Fusarium oxysporum f. sp. ciceris. Four isolates selected as potential antagonists were identified as Pseudomonas putida (PDBCAB 19), P. fluorescens (PDBCAB 2), P. fluorescens (PDBCAB 29) and P. fluorescens (PD BCAB 30) and their ischolar_main colonizing ability was tested. The total rhizosphere population was the highest (log cfu 6.4) for P.fluorescens (PDBCAB 29) after four days of germination. The rhizosphere population stabilized (log cfu 4.0 to 5.0) after eight days of germination. Three pathogens namely F. oxysporum f. sp. ciceris (wilt pathogen),R. solani and M.phaseolina (ischolar_main rot pathogens) were targeted by the four selected antagonists under greenhouse conditions. The maximum plant stand (100%) was observed with P.jluorescens (PDBCAB 29 and 30) treated pots for R. solani and M. phaseolina. P. putida (PDBCAB 19) and P. fluorescens (PDBCAB 30) were able to fully control F. oxysporum f. sp. ciceris. All the four antagonists promoted growth of chickpea. P. fluorescens isolates (PDBCAB 29 and 30) produced the maximum growth. Survival of P. fluorescens (PDBCAB 29) in a talc based formulation was monitored over a period of 90 days at room temperature.

Keywords

Antagonism, Chickpea, Plant Growth Promotion, Rhizospheric Bacteria, Survival Talc, Wilt.

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C. Sankaranarayanan ¹, S. S. Hussaini ¹, P. Sreerama Kumar ¹, R. D. Prasad ¹

Affiliations
1 Project Directorate of Biological Control, Post Bag No. 2491, H. A. Farm Post, Bangalore 560024, Karnataka, IN

Abstract

In vitro experiment was conducted to study the effect of different fungal filtrates against Meloidogyne incognita (Kofoid and White) Chitwood, and M. javanica (Treub) Chitwood. Significant nematode mortality was observed in all the culture filtrates and as the exposure time increased there was an increase in mortality of nematodes recorded. The culture filtrates of Trichoderma harzianum Rifai (PDBCTH 2) and T. koningii Oudem recorded 100 per cent mortality within 24 h of exposure in both the nematode species. Culture filtrates of different fungi under study, except T. harzianum (PDBCTH 7 and PDBCTH 8) against M. incognita and PDBCTH 8 against M. javanica, recorded 100 per cent nematode mortality at 96 h of exposure.

Keywords

Culture Filtrate, Gliocladium spp., Meloidogyne incognita, M. javanica, Trichoderma spp.

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R. D. Prasad ¹, T. Navaneetha ¹, L. Venkateswar Rao ²

Affiliations
1 ICAR-Indian Institute of Oilseeds Research, Rajendranagar, Hyderabad – 500030, Telangana, IN
2 Department of Microbiology, Osmania University, Hyderabad – 500030, Telangana, IN

Abstract

Nine potential Trichoderma strains were tested for mycoparasitic, defence enzyme activity and ischolar_main colonizing behaviour against Macrophomina phaseolina and Fusarium oxysporum f. sp. carthami in safflower (Carthmus tinctorius L). Among them three strains viz., T. harzianum Th4d, T. asperellum TaDOR7316 and T. asperellum Tv5 were found to be most effective showing superior antagonistic activity. Hyphal interaction studies revealed that the inhibition was caused by an interaction that took place in close contact with the host hypha, causing lysis, swelling and coiling of mycelia resulting potentially reduced mycelial growth of M. phaseolina and showed lytic enzymes activity to various extent in Th4d, Tv5 and TaDOR 7316. These strains were also able to solubilize inorganic (P). Increased activity of defense related enzymes viz., peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) activity in these three potential strains pre-treated safflower plants challenged with M. phaseolina was observed. PO, PPO and PAL activity was also increased two-three folds more in all these bioagents. Interaction between the bioagents and the safflower ischolar_main system showed profuse adhesion of hyphae to the plant ischolar_mains as well as colonization of the ischolar_main epidermis and cortex cells but not the vessels at early stages of safflower ischolar_main system. Levels of hydrogen peroxide (H₂O₂) in the bioagents treated leaves and untreated (control) were determined microscopically. Application of these bioagents under field conditions reduced the incidence of ischolar_main rot and Fusarium wilt, increased growth and plant biomass to a reasonable extent with better ischolar_main colonization, which is directly correlated with the resistance of the plant against infection and high seed yield, was observed with bioagents treatment. Thus, it is evident that the hyphal interaction and enzymes play a key role to stimulate the defense mechanism which aid in disease management as well as plant growth promotion of the host plant against pathogen attack.

Keywords

Antagonistic Activity, Defense Enzymes, Plant-Fungus Interaction, Safflower, Trichoderma spp.

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