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Management of Root Rot (Rhizoctonia solani) of Fenugreek through Newer Combined Formulations of Fungicides
First Online 28-09-2020|
Methods: During 2016-17 to 2017-18 cropping seasons, this study was carried out with the aim to manage the disease by means of using six fungicides including newer formulations (hexaconazole and tebuconazole + trifloxystrobin) under in vitro and field conditions.
Result: The result of in vitro study with tebuconazole + trifloxystrobin was found to be most fungitoxic and inhibited mycelial growth cent per cent at 200 and 500 ppm concentrations. Seed treatment with tebuconazole + trifloxystrobin (@ 0.2%) was found highly effective in reducing disease incidence (83.12%) and in increasing seed yield (84.71%) under field conditions. Thus, it can be concluded that the use of newer combined formulation as seed treatment before sowing provide us alternative source to manage root rot disease of fenugreek.
Rajasthan stands first in the production with more than 80 per cent area under fenugreek cultivation in India. Other major production centres of fenugreek in India are Madhya Pradesh, Gujarat, Haryana, West Bengal and Uttaranchal (Anonymous, 2018).
Fenugreek attacked by a number of fungal diseases viz., root rot (Rhizoctonia solani), downy mildew (Peronospora trigonellae), powdery mildew (Erysiphe polygoni and Leveillula taurica), wilt (Fusarium oxysporum), leaf spot (Cercospora traversiana), charcoal rot (Macrophomina phaseolina) and rust (Uromyces anthyllidis) (Godara et al., 2010). Among these, root rot also known as collar rot or foot rot or damping off of fenugreek caused by Rhizoctonia solani is one of the most important diseases which reduce the yield of the plant significantly. The main symptom of this disease is damping off. The freshly emerged seedlings fall over and die and most of the seedlings may die at pre- or post-emergence in severely infected areas. They may also develop foot rot and reddish brown cankers on root and stem near the ground level. The pathogen mainly attacks the root and underground parts, but it is also capable of infecting the other plant parts like the green foliage parts, the seeds and the hypocotyls (Acharya et al., 2014). The roots of infected plants are poorly developed; finer roots are either not formed or rotted. Plants show stunted growth and can easily be pulled out. Heavy losses are incurred due to root rot. Under natural field conditions, the incidence of root rot of fenugreek was recorded up to 20.00 per cent in Jaipur district of Rajasthan. Singh and Rao (2015) reported 34.67 per cent incidence of root rot of fenugreek caused by Rhizoctonia solani with yield loss of 55.26 per cent from Chhattisgarh. Rani and Hedge (2017) recorded 48.35 per cent root rot incidence in fenugreek caused by Rhizoctonia solani Kuhn in Karnataka.
In lieu of disease incidence and yield losses, some newer fungicides were tested in comparison to already recommended ones for two consecutive years (2016-17 and 2017-18) under field conditions for managing the disease and increasing crop productivity for the benefit of the end users.
MATERIALS AND METHODS
All the glassware were cleaned with potassium dichromate sulphuric acid solution, washed with sterilized water, sterilized in hot air oven at 160°C for two hours. Potato dextrose agar medium was sterilized by autoclaving at 1.045 kg cm2 pressure for 20 minutes. Roots of diseased plants of fenugreek were first washed under the tap water and then cut into small pieces along with healthy portion. These pieces were surface sterilized by dipping in 1 per cent sodium hypochlorite solution for 1 minute. After three consecutive washings with sterilized distilled water, the pieces were transferred to autoclaved PDA medium in Petri plates and incubated at 25+1°C in BOD incubator up to 7 days. Pure culture of the fungus was obtained by hyphal tip technique. The isolated and purified fungus was identified as Rhizoctonia solani on the basis of morphological and colony characters and further got confirmed from ITCC (with I.D. No. 10.836.18) New Delhi.
In vitro studies
Effect of fungicides on mycelial growth
Efficacy of six systemic and non-systemic fungicides viz., hexaconazole 5% SC, tebuconazole 50% WG +trifloxystrobin 25% WG, carbendazim 50% WP, carboxin 37.5% + thiram 37.5%, carbendazim 12% WP + mancozeb 63% WP and captan 70% WP + hexaconazole 5% WP were evaluated for antimycotic effect against Rhizoctonia solani by Poisoned Food Technique at 100, 200 and 500 ppm. Required quantity of each fungicide was added aseptically to 100 ml sterilized PDA medium in 150 ml flask so as to get concentration of 100, 200 and 500 ppm. Just before pouring in sterilized Petri plates, the flasks were shaken several times to ensure proper and uniform distribution of the fungicide. Poisoned medium was poured in sterilized Petri plates and allowed to solidify. Medium without fungicide served as control. Three replications were maintained for each treatment. Each plate was inoculated with 5 mm mycelium bit of the pathogen in the centre of plate. Inoculated plates were incubated at 25+1°C for 7 days. The linear growth of test fungus was recorded and per cent growth inhibition was calculated by Vincent’s (1947) formula:
C =Diameter of the colony in check (average of both diagonals), T = Diameter of colony in treatment (average of both diagonals).
In vivo studies
Effect of fungicides on disease incidence and seed yield
A field experiment was conducted during Rabi 2016-2017 and 2017-18 at Agronomy Farm, SKN College of Agriculture, Jobner (Jaipur) in randomized block design (RBD) with three replications in 2 m × 2 m plots, using RMT-305 as test variety, under artificial inoculation conditions. All the recommended agronomic practices were followed to raise the crop. All the fungicides viz., carbendazim (0.1%), carboxin + thiram (0.2%), hexaconazole (0.2%), tebuconazole + trifloxystrobin (0.2%), carbendazim + mancozeb (0.2%) and captan + hexaconazole (0.2%) were applied as dry seed treatment before sowing. For artificial inoculation, inoculum multiplied on sterilized sorghum grains was mixed at the rate of 20 g/m row at the time of sowing (i.e. first week of Nov.). The healthy and diseased plants were counted at 60 days after sowing. Per cent disease incidence (PDI) and per cent disease control was calculated as per following formulae.
RESULTS AND DISCUSSION
All the tested six fungicides significantly inhibited the mycelial growth at all the concentrations (100, 200 and 500 ppm) tested (Table 1). Out of these fungicides, tebuconazole + trifloxystrobin had completely inhibited the growth of the pathogen at 200 and 500 ppm concentrations and also gave maximum inhibition at 100 ppm concentration and (93.33%) and found most effective in comparison to older fungicides. Hexaconazole was also rated better in inhibition (89.23%) at 500 ppm. The importance of chemicals cannot be denied in disease management strategies. Our results are in accordance with the findings of Atia et al., (2015) who evaluated nine fungicides against R. solani causing root rot of tomato in vitro and in vivo conditions. The fungicides, propiconazole and tebuconazole + trifloxystrobin were found to be highly effective (100% inhibition) at 250, 500 and 1000 ppm concentrations.
Effect of fungicides on root rot incidence and seed yield (in vivo)
All the fungicides evaluated (Table 2) were found statistically significantly superior over control in reducing disease incidence and in increasing seed yield during both the years (2016-17 and 2017-18) of testing. Among all the fungicides, at pooled level, minimum disease incidence (8.44%) and maximum seed yield (1939.50 kg/ha) were recorded by treating the seeds with tebuconazole + trifloxystrobin (@ 0.2%) and hexaconazole (14.73% and 1796.00 kg) was also found effective. Seed treatment with tebuconazole + trifloxystrobin (0.2%) was proved to be the most effective in reducing disease incidence (83.12%) and in increasing seed yield (84.71%) over control. Seed treatment with tebuconazole + trifloxystrobin and hexaconazole were found statistically at par to each other in increasing seed yield over control. Similar results with other crops have been made by Atia et al., (2015) who tested nine fungicides against R. solani causing root rot of tomato in vivo conditions. Among them, propiconazole and tebuconazole + trifloxystrobin were found to be highly effective in controlling disease. Bag (2009) has also been reported that tebuconazole + trifloxystrobin is the most effective fungicide against sheath blight of rice caused by R. solani in reducing disease severity and in increasing yield. Tebuconazole alone, has also been reported to be effective on other crops (Meena and Chatopadhyay, 2002; Yadav et al., 2003, Dutta and Kalha, 2011 and Prasad et al., 2017).
- Acharya, K., Chakraborty, N., Chatterjee, S. and Basu, S.K. (2014). Fungal Diseases of Fenugreek. Fenugreek Special Issue, Mar/Apr 2014. American J. Social Issues and Huminities. pp.176.
- Anonymous. (2018). Spices Board of India, Ministry of Commerce and Industry, Govt. of India. www.indiaispices.com.
- Atia, E.A., Somasekhara, Y.M. and Gowda, N.C.N. (2015). Evaluation of new fungicide molecules for the management of tomato (Solanum lycopersicum Mill.) root rot (Rhizoctonia solani Kuhn). Mysore J. Agric. Sci. 49(4): 693-697.
- Bag, M.K. (2009). Efficacy of a new fungicide ‘trifloxystrobin 25% + tebuconazole 50%’ 75WG against sheath blight Rhizoctonia solani Kühn) of rice. Journal of Crop and Weed. 5: 224-226.
- Choudhary, S., Meena, R.S., Singh, R. and Vishal, M.K. (2013). Assesment of genetic diversity among Indian fenugreek (Trigonella foenum-graecum L.) varieties using morphological and RAPD Markers. Legume Research. 36(4): 289-298.
- Dutta, U. and Kalha, C.S. (2011). In vitro evaluation of fungicides, botanicals and bio-agents against Rhizoctonia solani causing sheath blight of rice and their integration for effective management of disease under field condition. Ind. J. Applied Res. 26: 14-19.
- Godara, S.L., Kapoor, B.B.S. and Rathore, B.S. (2010). Disease Management of Spices Crops. Madhu Publications, Bikaner, pp. 97-100.
- Laila, O., Murtaza I., Abdin, M.Z., Ahmad, S., Ganai, N.A. and Jehangir, M. (2013). Development and validation of HPTLC method for simultaneous estimation of diosgenin and quercetin in fenugreek seeds (Trigonella foenum-graceum). pp1-8.
- Meena, P.D. and Chattopadhyay, C. (2002). Effect of some physical factors, fungicides on growth of Rhizoctonia solani Kuhn and fungicidal treatment on groundnut seed germination. Ind. J. Pl. Protec. 30: 172-176.
- Prasad, R., Vidhyasagar, M., Devi, B.U., Koteswar, G. and Rao, S.R. (2017). In vitro evaluation of fungicides and biocontrol agents against Rhizoctonia solani in tomato. Inter. J. Pl. Soil Sci. 17: 1-9.
- Rani, N. and Hegde, Y.R. (2017). Survey for the incidence of root rot/wilt of fenugreek in Northern Karnataka, India. Inter. J. Curr. Microbiol. App. Sci. 6(5): 1564-1569.
- Rathore, S.S., Saxena, S.N., Kakani, R.K., Sharma, L.K., Agrawal D. and Singh, B. (2017). Genetic variation in fatty acid composition of fenugreek (Trigonella foenum-graecum L.) seed oil. Legume Research 40(4): 609-617.
- Singh, A.K. and Rao, S.S. (2015). Management of root rot disease of fenugreek. J. Spices Aromatic Crops. 24 (1): 58-60.
- Vincent, J.M. (1947). The esters of 4- hydroxyl benzoic acid and related compounds. Method for the study of their fungistatic properties. J. Ind. Sci. Landon. 16: 746-755.
- Yadav, S.S., Tripathi, N.N. and Kalita, M.K. (2003). Comparative efficacy of fungitoxicants in controlling root rot of cotton caused by Rhizoctonia solani Kuhn. Annals Agri. Bio. Res. 8: 61-63.
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