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1 Legume Research, 38 (1) 2015: Print ISSN: / Online ISSN: AGRICULTURAL RESEARCH COMMUNICATION CENTRE Cost effective strategies for the management of Fungal leaf spot of greengram caused by Cercospora canescens Ell. & Mart. under temperate condition of Jammu and Kashmir F.A. Bhat*, G.N. Bhat, A. Anwar and F.A. Mohiddin Division of Plant Pathology, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar , Srinagar, India. Received: Accepted: DOI: / ABSTRACT Greengram sown from May-26 to July-5 at 10 days interval in Kashmir manifested variable disease scores. While May-26 sown crop suffered significantly lower leaf spot intensity (25 %) and pod infection (34 %), the following sowings such as June-5, June-15, June, 25 and July-5 suffered 32-47, and per cent leaf spot intensity and pod infection, respectively. May-26 sowing supported maximum seed yield (8.2 q/ha) and a proportionate decrease in seed yield of late sowings was recorded with lowest (7 q/ha) obtained in July-5 sown crop. Fungicides were evaluated as seed treatment as well as one or two foliar applications. Seed treatment with carbendazim and captan showed poor results in both disease control and seed yield. However, application of carbendazim (0.05 %) at first appearance of disease followed by another spray with hexaconazole (0.02 %) ensured significant reduction in pod infection (77 %) and leaf spot intensity (68 %) besides supporting proportionately attractive seed yield ( q/ha) at an acceptable B:C ratio (6.38:1). Key words: Cercospora canescens, Green gram, Leaf spot, Pod infection. INTRODUCTION Jammu and Kashmir is one of the important pulse growing regions with an area of thousand hectares under different pulses and producing thousand tonnes of pulses annually including about 34 per cent from Kashmir province (Anonymous, 2008a,b). The state also happens to be important consumer of pulses and relies mainly on import from different states of India to meet the requirement. The crop experiences several stresses predominated by a leaf spot caused by Cercospora canescens which is a recognized destructive disease of the crop worldwide for inflicting qualitative and quantitative losses ranging from 23 to 96 per cent under natural epiphytotic conditions (Kasno, 1990; Iqbal et al., 1995; Kaur, 2007). Until now very few varieties of greengram have been found resistant or moderately resistant to C. canescens, though several improved varieties have been developed through selection, hybridization and mutation. Keeping in view the importance of greengram as well as the associated disease, the present study was, therefore, intended for efficient and cost effective management strategies. MATERIALS AND METHODS The present investigations were conducted in the experimental field of the Department of Plant Pathology, Sher-e-Kashmir University of Agricultural Sciences and *Corresponding author s farooqahmad_bhat@ymail.com. Technology of Kashmir, Shalimar, located at 34 o 472 north latitude and 74 o 522 east longitude at an elevation of 1591 meters above mean sea level. Five sowing dates viz., May 26, June 05, 15 and 25, and July 05 were evaluated in randomized block design (RBD) with four replications and plot size of 3 x 3m while maintaining plant spacing of 30x10 cm during kharif 2009 and Leaf spot intensity was recorded in 0-7 rating scale, where 0 = no infection, 1 = One spot to 20 per cent diseased area, 3 = per cent diseased area, 5 = per cent diseased area, and 7 = >60 per cent diseased area. The disease was calculated by using the following formulae. Seed yield was calculated from net yield of four rows (3 m) in each plot and was converted into quintals per hectare (q/ha) for interpretation. Seed yield was calculated from net yield of four rows (3 m) in each plot and was converted into quintals per hectare (q/ha) for interpretation. (nv) NG where n= number of leaves in a category v = numerical value of category N = total of leaves examined and G = maximum category value.

2 110 LEGUME RESEARCH Number of diseased pods Total number of pods observed Three systemic and three protective fungicides were applied in different combinations (Table-1) to test their effectiveness against the disease under epiphytotic conditions during kharif 2009 and The greengram cv. Shalimar Mung-1 was sown in 3x3m plots with plant spacing of 30x10cm and interplot buffer zone of 1m. First spraying was given at the appearance of initial disease symptoms and the 2 nd spray, wherever applicable, fifteen days later at the rate of 1000 liters spray mix per hectare. Disease was recorded at pod maturity stage for which random sample of 10 plants was taken from each plot representing a replication. Cost benefit ratio was calculated following market rates of year 2010 as recorded by Abbaiah and Devi (1992). RESULTS AND DISCUSSION Effect of sowing dates: The terminal disease and seed yield of greengram showed an identical trend over years and the poled data there of are presented in Table-1. Pod infection was significantly low (34.50 & %) in May-26 and June- 5 sown crops followed by June-15 sown crop exhibiting per cent pod infection. Highest pod infection (64.24 %) was observed in July sown crop. The leaf spot intensity differed significantly among different sowing dates with lowest (25.27 %) recorded in May-26 sown crop and highest (47.16 %) in July-05 sown crop. The leaf spot intensity recorded for June sown crops ranged from to per cent and those of June-25 and July-05 were statistically at par. Grain yield was also affected by delayed sowing and was lowest (7.37 q/ha) in July 5 sown crop. The yield recorded for May-26 sowing (8.18 q/ha) was comparatively higher but statistically at par with June-5 sowing giving 8.04 q/ha. The data revealed progressive increase in terminal leaf spot intensity and pod infection, and a corresponding decrease in seed yield with delayed sowing. These results confirmed prior reports (Gupta and Saharan, 1974; Sud and Singh, 1984b; Ahmad and Ahmad, 1995) that alteration in date of sowing significantly influences the terminal disease severity and crop yield. The increase in disease scores could be due to more conducive weather which prevailed during late kharif and/or infected crop stands of early sowing which served as proximate source of secondary inoculum for subsequent sowings. On the other hand this disease reportedly appeared in crop stands during reproductive phase which follows closing of canopy under normal crop geometry (Mew et al., 1975; Mathur et al., 1989). The influence of microclimate vis-a-vis dense crop canopy on development of foliar diseases was also reported by Perrier et al. (1972) and Beckman and Payne (1982). However, the disease appeared well before flowering in late sown crop though of lower intensity. The appearance of disease postflowering in early sown crop and pre-flowering in late sown crop uncovered the role of weather besides recognizing the influence of inoculum load. Therefore, the prolonged conducive periods as well as availability of more secondary inoculum in the vicinity of late sown crop were viewed as the possible factors which might have supported higher disease scores in late sown crop. Seed yield was also significantly influenced by disease vis-a-vis sowing dates. There are several reports of this disease being detrimental to greengram for causing severe yield losses (Kasno, 1990; Iqbal et al., 1995; Kaur, 2007). The decrease in seed yield associated with late sown crop was due to prolonged association of C. canescens, a polycyclic pathogen and the late sown greengram stands when compared to May-25 and June-05 sown crops which escaped disease attack beyond flowering. The significance of pre- and post-flowering stages in determining the yield structure of greengram was also emphasized by Lamptey and Ofei (1977), Chand et al. (2003), and Vijaylaxmi and Bhattacharya (2006). Moreover, the yield structure is also determined by weather factors especially rain which directly influences the crop establishment and subsequent growth. This also needs to be taken under consideration though it was uniformly distributed during the period of present investigation. Effect of chemicals: All fungicides were found significantly better in managing the disease when used as foliar sprays during both the years (Table-2). The data reveal that T 8 significantly reduced the pod infection and leaf spot intensity TABLE 1: Effect of sowing date on disease and subsequent seed yield of greengram. Sowing date Pod infection (%) Leaf spot intensity (%) Seed yield (g/9m 2 ) Seed yield (q/ha) 26-May (35.95) (30.13) June (38.72) (34.58) June (42.98) (39.26) June (50.56) (41.71) July (53.42) (43.35) C.V. (%) C.D. (P=0.05) Figures in parenthesis are transformed (arcsine) values.

3 Volume 38, Issue 1, TABLE 2: Efficacy of fungicides against disease of greengram. Treatment Pod infection(%) Leaf spot intensity(%) Seed yield(g/9m 2 ) T 1 - Carbendazim 0.1 %) (38.57) (42.61) (33.52) (39.08) T 2 - Captan 0.3 %) (38.63) (43.89) (34.35) (38.90) T 3 - Carbendazim 0.1 %) + Carbendazim 0.05 %) (30.93) (35.20) (26.40) (31.63) T 4 - Carbendazim 0.1 %) + Hexaconazole 0.02 %) (32.49) (36.43) (28.63) (33.43) T 5 - Carbendazim 0.1 %) + Difenconazole 0.02 %) (31.24) (35.61) (27.99) (32.71) T 6 - Carbendazim 0.1 %) + Carbendazim 0.05 %) +Chlorothalonil 0.2 %) (21.23) (27.74) (21.46) (25.25) T 7 - Carbendazim 0.05 %) + Hexaconazole 0.02 %) (16.83) (20.28) (17.24) (23.03) T 8 - Carbendazim 0.05 %) + Difenconazole 0.02 %) (16.46) (18.85) (15.63) (21.76) T 9 - Carbendazim 0.05 %) + Chlorothalonil 0.2 %) (23.61) (28.85) (22.71) (26.01) T 10 - Carbendazim 0.05 %) + Captan 0.2 %) (27.27) (32.57) (25.07) (30.84) T 11 - Carbendazim 0.05 %) + Mancozeb 0.2 %) (26.64) (31.68) (23.99) (28.43) T 12 - Thiophanate methyl 0.05 %) + Chlorothalonil 0.2 %) (24.76) (30.32) (23.40) (28.07) T 13 - Check (no fungicidal application) (39.84) (44.27) (35.30) (40.61) CV (%) CD (P=0.05) st = seed treatment; sp = spray; Parenthetic figures are transformed (arcsine) value.

4 112 LEGUME RESEARCH to 8.11 and 7.30 per cent, respectively, during Results exhibited by T 7 were statistically at par with those of T 8. T 6 was the third best in reducing the pod infection and leaf spot intensity to and per cent, respectively. It, however, was statistically at par with T 9 which showed and per cent pod infection and leaf spot intensity, respectively. T 12 also showed appreciable effect exhibiting below 18 per cent pod infection and leaf spot intensity. The least effective among foliar spray treatments was T 4 which could reduce the pod infection and leaf spot intensity to mere 28.9 and per cent, respectively. The results shown by seed treatments (T 1 and T 2 ) were comparable with check plots. Foliar application also increased grain yield with significantly higher ( g/plot) provided by T 8 followed equally by T 7 for giving g/plot. The grain yields recorded with T 4 ( g/plot) and T 5 (754 g/plot) were least but significantly higher when compared to check. Like in disease, the effect of T 1 and T 2 was non-significant in grain yield. During second year, an increase in disease was noticed compared to previous year. However, it was again T 8 that produced best effect with lowest pod infection (10.54 %) and leaf spot intensity (13.78 %) besides supporting higher seed yield (808 g/plot). T 7 exhibited the respective figures as 12.05, and , and was statistically at par with T 8. While as minimal and statistically indifferent effects were shown by T 4, T 5 and T 3 wherein per cent pod infection and per cent leaf spot intensity was recorded with a corresponding seed yield of g/ plot. T 6 was adjudged third best for supporting the higher yield ( g/plot) and reducing the pod infection and leaf spot intensity to and per cent. T 9 produced alike effect with grain yield of g/plot besides reducing pod infection and leaf spot intensity to and 22.7 per cent, respectively. T 12 and T 11 also produced statistically indifferent results with yield 768 and 774 g/plot, pod infection and per cent and leaf spot intensity 22.2 and 22.7 per cent. T 1 and T 2 consistently failed to produce any significant effect on disease and grain yield. The data of two years study reveals that single foliar application of systemic fungicides reduced the pod infection and leaf spot intensity. Whereas foliar (two spray) treatments showed appreciable reduction in pod infection and leaf spot intensity besides increasing seed yield. However, apparently the best results were provided by consecutive systemic sprays (T 7 and T 8 ) with highest increase in seed yield. Although above fungicidal combinations were not evaluated earlier as such, the appreciable effect of carbendazim (Chand et al., 2003; Chhata et al., 2010), thiophanate methyl (Sharma, 1998), hexaconazole (Khunti et al., 2005), difenconazole (Kapadiya TABLE 3: Economics of fungicidal application in the management of Cercospora leaf spot of greengram. Treatment Average seed Increase over Value of added Cost of treatment (Rs/ha) Benefit Benefit yield (q/ha) check (q/ha) yield (Rs/ha) # ST SP1 SP2 *Misc. Total (Rs/ha) cost ratio : : : : : : : : : : : : #@ Rs 80/ kg, *including labour and operation Rs 500/spray.

5 Volume 38, Issue 1, and Dhruj, 1999), chlorothalonil (Yadav and Singh, 1999) and mancozeb (El-Gantiry et al., 1990) against Cercospora spp. on greengram and allied crops have been reported. The single application was not effective as the pathogen was polycyclic and interacted with host for over 40 days in a season. Although it confirmed earlier reports (Grewal et al., 1980; Bhardwaj and Thakur, 1991; Mittal 1991), the findings contradicted some other reports (Ahmad, 1985; Chand et al., 2003) that seed treatment and/or one spray of carbendazim given at emergence of symptoms was effective against Cercospora leaf spot of greengram. However, such reports persay contradicted the above fact that C. canescens is a polycyclic pathogen requiring incubation period of about a week besides having multiple modes of secondary dispersal. The economics of fungicide treatments was worked on averaged data of 2009 and 2010 (Table-3). Among foliar treatments, highest increase in yield worth Rs /ha was provided by T 8. T 7 was next best for giving Rs additional returns per hectare. However, the benefit cost ratio was better with T 7 (6.38:1) when compared to T 8 (4.9:1). The benefit cost ratio (3.05:1) associated with T 11 for giving additional 1.0 q seed yield worth Rs. 8000/ha was third preferable two spray treatment. Among one spray treatments, appreciable benefit was observed with T 3 (Rs. 5402/ha) at a benefit cost ratio of 6.45:1 which was better than 1.5:1 representing T 9, a two spray treatment. Although B:C ratios in T 3 (carbendazim seed treatment + carbendazim spray) and T 4 (carbendazim seed treatment + hexaconazole spray) were also considerable, the benifit, however, was about half of T 7. It was due to overall better performance of above fungicides in minimizing the disease and avoiding resultant yield losses, though the cost also decided their economics. The comparatively better yield provided by carbendazim spray was due to its phytotonic effect (Chand et al., 2003). The findings were in agreement with prior reports which maintained that Cercospora leaf spot caused reduction in greengram yield (Kasno, 1990; Iqbal et al., 1995; Kaur, 2007) or application of fungicides gave additional seed yield by impeding disease outbreaks (Mian et al., 2000; Chand et al., 2003; Khunti et al., 2005). The failure of seed treatment with carbendazim and captan in supporting better seed yield was first such evidence and is contradictory to prior reports (Mittal, 1991 & 1994; Ahmad, 1985) that seed treatment with fungicides reduced leaf spot intensity significantly. However, it was ascribed to the nature of disease appearance and its subsequent spread in crop stands. The disease appeared towards reproductive phase when the possible effect of seed treatment would have been over. Moreover, greengram has epigeal germination and the seed coat usually comes along the cotyledons. In some cases when diseased seeds germinated the primary leaves were held close to cotyledons in unshed seed coat. This usually led to infection of primary leaves which might have served as a source of secondary inoculum. Even when such seedling establish into a healthy plant, the infected cotyledons may serve as primary source of inoculum once the favourable conditions are met. In this context when carbendazim is not known to cure cotyledon infection it is hard to agree that seed treatment can influence seed yield by reducing leaf spot intensity in a crop stand. Therefore, we stick to our finding that seed treatment with carbendazim and captan against leaf spotting pathogen, C. canescens, produced results just comparable to untreated check. However, the study needs to be conducted in controlled environment to check the role of airborne innocula coming from untreated and diseased plants which under open field conditions can t be ruled out. REFERENCE Abbaiah, K. and Devi, T.P. (1992). Evaluation of fungicides against powdery mildew and cercospora leaf spot of blackgram. India J Pl Prot. 20: Ahmad Q. (1985). Fungicidal control of cercospora leaf spot of mungbean (Vigna radiata). India Phytopath. 38: Anonymous, (2008a). Agricultural Statistics at a Glance Dir. Econ. Stat., Dept. Agri. Coop., Govt. of India, New Delhi. Anonymous, (2008b). Economic Survey Dir. Econ. Stat., Govt. of Jammu & Kashmir. Bhardwaj, C.L. and Thakur, D.R. (1991). Efficacy and economics of fungicide spray schedules for control of leaf spots and pod blight in urdbean. India Phytopath. 44: Backman, P.M. and Payne, G.A. (1982) External growth, penetration and development of Cercospora zea-maydis in corn leaves. 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