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*Corresponding author’s e-mail: bunchy@rediffmail.com. 1CSK Himachal Pradesh Krishi Vishvidylaya, Rice and Wheat Research Centre, Malan,Kangra -176 47, India. 2CSKHPKV, Research Sub Station, Akrot, Una-177211, India..

Legume Research, 39 (6) 2016 : 1038-1042Print ISSN:0250-5371 / Online ISSN:0976-0571

Fungicidal management of web blight of urdbean caused by Rhizoctonia solaniAshwani K. Basandrai*1, Daisy Basandrai1 and B.K. Sharma2

CSK Himachal Pradesh Krishi Vishvidylaya, Himachal Agricultural Research and Extension Centre,Dhaulakuan, Sirmour -173 001, India.Received: 27-01-2015 Accepted: 03-08-2016 DOI: 10.18805/lr.v39i6.6646ABSTRACTWeb blight caused by Rhizoctonia solani causes huge yield loses in urdbean (Vigna mungo). All the commercially grownvarieties are susceptible. Hence, more than ten fungicides were evaluated as foliar sprays during kharif season 2005, 2007-2010 using susceptible variety UL 338. Two foliar sprays of fungicides, namely; hexaconazole 5EC (Contaf 5EC)@ 0.1%,difenconazole 25EC (Score 25EC) @ 0.05%, carbendazim 50WP (Bavastin 50WP) @ 0.1% and propiconazole 25EC(Tilt 25EC) @ 0.1% significantly reduced the disease severity resulting in 81.1, 80.6, 65.9 and 76.2% control over unsprayedcheck with corresponding mean yield of 872, 821, 791 and 754 kg/ha compared with the mean yield of 584 kg /ha inunsprayed control . The net benefit for the two foliar sprays of hexaconazole 5EC, difenconazole 25EC, propiconazole 25ECand carbendazim 50WP and chlorthalonil 50WP, has been worked out to be Rs.10229, 6891, 6375, 4524 and 3274, respectivelyfor the crop grown for the grain purpose (@Rs. 4300/q) with the cost: benefit ratio of 5.8, 3.1, 2.6, 4.0 and 1.8, respectively.In the crop, grown for the breeder seed purpose (Rs.12000/q), the net profit for foliar sprays of hexaconazole 5EC, difenconazole25EC, propiconazole 25EC, carbendazim 50WP and chlorthanonil was worked out to be Rs.32405, 25140, 17616, 22614 and16980 respectively with cost: benefit ratio of 16.0, 8.6, 7.3, 11.2 and 4.9, respectively. The same trend was observed forfoundation and certified seed also. The fungicides were effective in reducing the severity of powdery mildew also.

Key words: Fungicides, Powdery mildew, Rhizoctonia solani, Urdbean, Web blight.INTRODUCTION

Urdbean is an important pulse crop grownthroughout the world. India is the largest producer andconsumer of urdbean (Vigna mungo L.). The area under thecrop has increased from 1.84 million ha in 1965-66 to 3.24million ha in 2010-2011, correspondingly, the productionand productivity has increased from 0.55 to 1.74 milliontonnes and 300 to 534 kg/ha, respectively (http:/ /www.aicrpmullarp. res.in/ online/FormAYP_Guest CountrySearch. aspx? Name =AYP&Form No=1). Urdbean is animportant and assured kharif food legume in HimachalPradesh and other hilly states. Its mean yield (based on 2005-06 to 2009-2010 data) is 405 kg/ha ((http:/ /www.aicrpmullarp. res.in/ online/FormAYP_Guest CountrySearch. aspx?Name =AYP&Form No=1), is less comparedto the national average and the potential yield (10-15 q/ha)of the varieties recommended for cultivation in the state(http://www .hillagric. ac.in/ extension/ dee/pdf_files/Kharif_28-8-09.pdf). Among various factors responsible forthe low yield, diseases viz. mungbean yellow mosaic virus,urdbean leaf crinkle virus, Cercospora leaf spot (Cercosporacruenta Sacc. and C. canescens Ell. and Martin), Ascochytaleaf spot (Ascochyta phaseolorum Sacc), root rot(Macrophomina phseolorum), anthracnose (Colletotrichumtruncatum Schw) and web blight (Rhizoctonia solani Kuhn)take a heavy toll of the crop causing yield losses to the tune

of 20-30% (Dubey et a1. 2007). Among these, web blight isone of the most important fungal disease causingconsiderable damage by reducing seed quality and yield. Thedisease can be effectively and economically managed by thecultivation of resistant varieties, however, most of thecommercially grown varieties are susceptible and fewresistant sources with low level of resistance are available(Basandrai et al., 1999, 2003, Shailbala and Tripathi, 2007).The disease is seed, soil and air borne hence, it may beeffectively managed by cultural, chemical and biologicalmeans. Fungicides are the effective short term means tomanage the disease. Keeping this in view, some commerciallyavailable systemic and contact fungicides were evaluated asfoliar sprays and the results are reported herein.MATERIALS AND METHODSEvaluation of fungicides: The experiments were carriedout at the experimental farm of CSKHPKV, Hill AgriculturalResearch and Extension centre, Dhaulakuan, a hot spot forthe web blight, during the rainy season 2005 and 2007-2010using susceptible variety UL 338. Standard agronomicpractices were followed to raise the crop (http://hillagric.ac.in/extension/dee/publications.htm). Theexperiments were laid in randomized block design (RBD)with three replications in plots of 6m2 . Generally, the trialwas conducted during the first fortnight of July during theexperimental period. Fungicides Difenconazole (Score

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25EC) @0.05%, Hexaconazole (Contaf 5EC), Propiconazole(Tilt 25EC) @ 0.1%, Mancozeb 75 WP (Indofil M 45) @0.25%, Chlorothalonil (Kavach 75%) @ 0.2% and Copperoxychloride (blitox) @0.3% were applied as two foliar sprayswith the initiation of the disease and were repeated at 15days interval.Data recording:Disease severity: The data were recorded for terminaldisease severity (TDS) i.e. percentage foliage infected forweb blight on 50 randomly selected plants following 1-9scale (Table 1). It was used to calculate disease intensity asper the formulae given below:Per cent disease intensity =

Sum of individual rating scale X 100

No. of disease plant observation X maximum disease rating

During the cropping season 2009 and 2010 powderymildew appeared in epidemic form hence, its severity wasalso recorded in different treatments.Grain yield: The data for grain yield were recorded on plotbasis for all the treatments and was converted to quintal perhectare using the following equation:Yield (kg ha-1) = Yield per plot ×10,000/Area of plot

The economics of fungicidal spray treatment interms of increase in yield, net returns and cost: benefit ratiowas worked out at the existing support price of urdbean,and price of breeder, foundation and certified seed.Analysis of variance: The data were subjected to analysisof variance using CPCS 1 computer software.On farm trials: On farm trials were conducted in the districtof Sirmour to confirm the results.RESULTS AND DISCUSSION

The data on the web blight severity as affected bythe fungicidal sprays and yield are given in Table 2. All thetreatments resulted in significantly less terminal diseaseseverity as compared to no spray checks (ranging from 41.4-57.1% over the crop seasons. Fungicides difenconazole @0.05% resulted in the least mean disease severity (17.51%)with the corresponding 80.6% disease control over theunsprayed check treatment followed by hexaconazole 5EC(18.78%), propiconazole 25 EC (19.56%) carbendazim(24.52%), chlorothalonil 75 WP (32.12%) and mancozeb(31.32%) with corresponding % disease control of 81.1%,76.2, 65.9%, 53.99 and 47.5, respectively over the no spray

check. The fungicides were highly effective in reducing theseverity of powdery mildew also. No powdery mildew wasrecorded in plots spayed with difenconazole, hexaconazoleand chlorothalonil with corresponding 100% control overthe unsprayed check whereas, mean severity of powderymildew was 1.6% in plots sprayed with propiconaole 25EC.Grain yield: All the fungicides resulted in higher seed yieldas compared with the unsprayed check (426-762 kg/ha)during the year 2005 and 2007-2010). The highest mean yield(872 kg/ha) was recorded in hexaconazole 5EC comparedwith the mean yield of 584 kg /ha in unsprayed control (Table 1).It was followed by 821, 791, 762 and 749 kg/ha in case ofDifenconazole 25EC (0.05), Carbendazim 50WP (0.1)chlorothalonil (0.2%) and Propiconazole 25EC (0.1),respectively .Economics of fungicidal application: The cost of twofungicidal sprays of hexaconazole @ 0.1%, difenconazole25EC @ 0.05%, carbendazim 50WP @ 0.1%, propiconazole25EC @ 0.1%, chlorothalonil (0.2%) and mancozeb (0.25%)including labour charges (at the existing market rates) wasRs. 2155, 3200, 2786, 4380, 2580 and 2486 ha, respectively(Table 3). The net benefit due to increase in yield for twofoliar sprays of hexaconazole 5EC, difenconazole 25EC,carbendazim 50WP, propiconazole 25EC and chlorothalonilhas been worked out to be Rs. 10229, 6891, 4524, 3274,2408 and 4611, respectively for the general crop (@Rs. 2900/q current support price) with corresponding cost: benefitratio of 5.8, 3.1, 4.0, 2.6, 1.8, 1.9 and 2.0, respectively.Quality seed (breeder, foundation and certified) productionis an important component of the State AgriculturalUniversities and State Department of Agriculture. In case,the crop is grown for the breeder and foundation seed purposethe net profit for foliar sprays of hexaconazole 5EC,difenconazole 25EC carbendazim 50WP, propiconazole25EC, chlorothalonil and mancozeb has been worked out tobe Rs. 32405 and 20885; 25140 and 15660; 22614 and14334; 17714 and 10814; 16980 and 9860; 11380 and 9860;and 17316 and 10716, respectively with corresponding cost:benefit ratio of 16.0 and 10.7; 8.6 and 5.8, 11.2 and 7.4;7.3 and 4.9; 4.9 and 3.3; and 7.3 and 4.9; respectively. Thenet profit for certified seed for foliar sprays of hexaconazole5EC, difenconazole 25EC carbendazim 50WP, propiconazole25EC, chlorothalonil and mancozeb has been worked out tobe, 18005, 13290, 12264, 9114, 8080 and 9066 respectively,with corresponding cost: benefit ratio of 9.4, 5.0, 6.5, 4.3,2.8 and 4.7 respectively.

Table1 : Disease rating scale for the web blight of urdbean

Percent Foliage infected Disease reaction Disease rating

No lesions on leaves Highly resistant 11-25% area covered by lesions Moderately resistant 325.1-50% area covered by lesions Moderately susceptible 550.1-75%area covered by lesions Susceptible 775.1-100% area covered by lesions Highly susceptible 9

1040 LEGUME RESEARCH - An International Journal

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Volume 39 Issue 6 (2016) 1041

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1042 LEGUME RESEARCH - An International Journal

As has been reported in the present studies, foliarsprays of carbendazim @ 0.05% were reported to be highlyeffective in reducing web blight severity and increasing theyield in urdbean (Shailbala and Tripathi, 2004, Shailbalaand Tripathi, H. S. 2010) and moongbean (Jhamaria andSharma (2002). Similarly, two foliar sprays of propiconazole@0.1% were found effective to reduce the web blight severityand increasing the grain yield in urdbean (Sharma andTripathi, 2001, Shilbala and Tripathi, 2004, 2010). Mishra etal., (2005) reported that among different fungicides screenedin vitro against R. solani infecting green gram, propiconazoleat 250 ppm caused 100.00% inhibition of the pathogen. Thepresent observations of high efficacy of hexaconazole andcarbendazim @0.1% for the management of web blight ofurdbean were further supported by the studies of Shailbalaand Tripathi (2004) on urdbean and Jhamaria and Sharma(2002) in moongbean. Efficacy of fungicides difenconazoleand cholorothalonil for the management of urdbean webblight has been reported for the first time.On-farm trials: On farm trials were conducted at the seedproduction farms of CSKHPKV, HAREC Dhaulakuan and

at farmers fields during the cropping season Kharif 2011 indistrict Sirmour and the results are summarized in Table 4.The least mean disease severity was recorded in foliar spraysof hexaconazole 5EC (3%) with corresponding yield of 767kg/ha followed by propiconazole 25EC (10% and 644kg/ha), difenconazole 25EC (10% and 630/ha) and,Carbendazim 50WP (25% and 520 kg/ha), respectively. Thefungicides were effective in reducing the severity of powderymildew at Dhaulakuan.

It is apparent from the studies that fungicideshexaconazole, difenconazole, propiconazole, chlorothaonilwere highly effective for the management of web blight ofurdbean. In the absence of desirable level of resistance inthe commercially cultivated urdbean varieties in the diseaseprone areas, these fungicides can be used to manage thedisease especially in the high value seed plots. Therecommendation on the management of web blight by thefoliar application of these fungicides has been included inthe package and practices of CSKHPKV, Palampur (http://www.hillagric.ac.in/research/dr/resworkshops / kharif/pdf/Recommendations_14-7-11.pdf).

Table 4: On farm trials on the management of web blight of mash (Kharif 2011).

Treatment Crop museum Surinder Pal Smt Vishnu Kanta Mean (HAREC Dhaulakuan) Bharapur (Sattiwala) Disease Yield Disease Yield Disease Yield Disease Yield severity (kg/ha) severity (kg/ha) severity (kg/ha) severity (kg/ha) (%) (%) (%) (%)

Hexaconazole (0.1) 2 800 2 750 5 750 3.0 767Difenconazole (0.05) 10 611 5 630 10 650 8.3 630.Carbendazim (0.1) 20 511 15 500 25 550 20.0 520Propiconazole (0.1) 10 620 10 656 10 656 10.0 644Control 50 444 45 475 60 475 51.7 465

REFERENCESBasandrai Daisy, K. Basandrai Ashwani and Singh Inderjit (2003). Multiple disease resistance against anthracnose, leaf

spot, powdery mildew and mung bean yellow mosaic virus in blackgram (Vigna mungo). J. Mycol. Pl. Pathol.33: 56-58.

Basandrai, A.K., Gartan, S.L., Basandrai, Daisy and Kalia, V. (1999). Black gram (Phaseolus mungo) germplasm evaluationagainst different diseases. Indian J. Agric Sciences 69: 506-508.

Dubey S.C., Singh Birender and Bahadur, P. (2007). Diseases of pulses and their ecofriedly management. In EcofriendlyManagement of Plant Diseases. (Shahid Ahamad and Udit Narain). pp 16-44.

Shailbala and Tripathi, H.S. (2004). Fungicidal management of web blight of urdbean. Indian-Phytopathology. 57: 99-100Jhamaria, S. L. and Sharma, O. P. (2002). Management of web blight of mung bean through chemicals and plant product.

Indian Phytopathology; 55:526.Mishra, B. D., Sahoo, K. C., Ghose Sugata and Rout M. K. (2005). In vitro evaluation of plant extracts, oilcakes and

agrochemicals against Web blight of green gram caused by Rhizoctonia solani. Journal of MycopathologicalResearch; 43:255-257.

Sharma, J. and Tripathi, H. S. (2001). Biological and chemical control of web blight disease of urdbean. Indian Phytopath.54:267-269.

Shailbala and Tripathi, H. S. (2007). Current status of research on web blight disease of urd bean: A Review. Agric. Rev.,28: 1-9.

Shailbala and Tripathi, H. S. (2010). Biological and chemical management of web blight disease of urd bean caused byRhizoctonia solani Kuhn. Journal of Plant Disease Sciences; 2010. 5:121-125.