Introduction

Mango (Mangifera indica L.), an important fruit crop belongs to family Anacardiaceae and is believed to be originated within a large area including north-western Myanmar, Bangladesh and north-eastern India. Mango is also the national fruit of India, which is the largest producer of mango in the world accounting for 52-63% of total production. The genus, Mangifera comprises of 41 species (Mukherjee, 1985), however total reported species now stands at 39 (Mukherjee and Stolon, 1989). All the edible cultivars of mango represent the species indica which originated in the Indian sub-continent. Looking to the seriousness of the disease and economic importance of the crop in this area, present investigations were undertaken to study the efficacy of fungicides against disease and to generate necessary information for suitable chemical management measures to minimize crop losses.

Materials and Methods

A field experiment was conducted for two years to know the effect of different fungicides under in vivo condition. A susceptible cv. Kesar was used for the study at Agricultural Experimental Station Paria NAU, Navsari. Treatments with seven fungicides i.e. three systemic, two non systemic and two combination fungicides (Table 1) with one check were laid out in Randomized Block Design (RBD). Each treatment was replicated thrice. Three sprays were undertaken. First spray was given at the initiation of the disease followed by second and third spray at a monthly interval in the same orchard of cv. Kesar having 8 years old tree severely affected by grey leaf blight disease. The disease intensity (%) was calculated at one day before each spray and 7 and 15 days after first, second and third spray. The data were analyzed as per randomized block design for interpretation and the disease control (%) was also worked out.

Formula for calculating disease intensity (%):

PDI =(∑ Ratings of infected leaves observed/No. of leaves observed x Maximum disease score)×100

Observations with regards to symptoms were recorded on the basis of graded scale (0-5) (Patel, 1988):

Table 1: Fungicides used during the study and their concentration used

Results and Discussion

From the perusal of data presented in Table 2, it is clear that all the treatments significantly reduced the grey leaf blight intensity as compared to control. During the first year, carbendazim 12%+mancozeb 63%  was found significantly superior over rest of the treatments with minimum grey leaf blight intensity (7.23%) followed by kresoxim methyl 43% SC (10.12%) which was at par with cymoxanil 8%+mancozeb 64% (11.24%). The next best treatment with lowest disease intensity was copper oxychloride 50% WP (12.21%) followed by carbendazim 50% WP (16.21%) which was at par with thiophanate methyl 70% WP (17.14%) and was followed by copper hydroxide 77% WP (21.12%). In case of control, highest disease intensity (51.23%) was recorded.

Table 2: Efficacy of fungicides against grey leaf blight disease of mango cv. Kesar

Maximum disease control (85.89%) was observed in carbendazim 12%+mancozeb 63% which was followed in decreasing order by kresoxim methyl 43% SC (80.25 %), cymoxanil 8%+mancozeb 64 % (78.06%), copper oxychloride 50 % WP (76.17%), carbendazim 50% WP (68.36%) and thiophanate methyl 70% WP (66.54%) whereas, copper hydroxide 77% WP had minimum disease control (58.77%) during the first year of study.

In the second year, carbendazim 12%+mancozeb 63% was found significantly superior over rest of the treatments with minimum grey leaf blight intensity (8.91%) followed by kresoxim methyl 43% SC (11.21%) which was at par with copper oxychloride 50% WP (12.23%). The next best treatment in recording lowest disease intensity was cymoxanil 8%+mancozeb 64% (14.23%) and carbendazim 50% WP (14.23 %) followed by thiophanate methyl 70% WP (16.23%) and copper hydroxide 77% WP (17.84%). In case of control, highest disease intensity (41.23%) was recorded.

During second year of study, maximum disease control (78.39%) was observed in carbendazim 12%+mancozeb 63%, which was followed in decreasing order by kresoxim methyl 43% SC (72.81%), copper oxychloride 50 % WP (70.33%), cymoxanil 8%+mancozeb 64%,  carbendazim 50% WP (65.48%) and thiophanate methyl 70 % WP (60.63%) whereas, minimum disease control (56.73%) was recorded in copper hydroxide 77% WP.

The pooled data for both the years indicated that among all the treatments, carbendazim 12%+mancozeb 63% was found significantly superior over rest of the treatments with minimum grey leaf blight intensity (8.07%) followed by kresoxim methyl 43% SC (10.67%). The treatment copper oxychloride 50% WP (12.22%) was found to be the next best treatment in order of effectiveness which was at par with cymoxanil 8%+mancozeb 64% (12.74%). The treatment carbendazim 50% WP (15.22%) was found to be superior over the treatment thiophanate methyl 70% WP (16.69%). The next best treatment in order of merit was copper hydroxide 77% WP (19.48%). In control, highest disease intensity (46.23%) was recorded.

Maximum disease control (82.54%) was observed in carbendazim 12%+mancozeb 63% which was followed in decreasing order by kresoxim methyl 43% SC ( 76.93%), copper oxychloride 50% WP (73.57%), cymoxanil 8%+mancozeb 64% (72.45%), carbendazim 50% WP (67.08%) and thiophanate methyl 70% WP (63.91%) whereas, copper hydroxide 77% WP had minimum disease control of 57.86%.

Similar results were reported previously for bioefficacy of fungicides under field condition by Chauhan (1984) who reported that carbendazim (0.3%) at pea stage before maturation of stone reduced the incidence of grey leaf blight disease of mango. Later on, Karthikeyan et al. (2002) reported that thiophanate methyl and carbendazim at 2.0% application in coconut were found best in reduction of the grey leaf blight disease index to 18.6 and 20.9%, respectively after three years of application. Kyada (2006) observed that among systemic, non-systemic and combination of fungicides, carbendazim+mancozeb (0.1%) was the best to reduce grey leaf blight disease with 69.30% reduction followed by carbendazim (0.05%) and iprodine+carbendazim (0.025%) tested in vivo. These results are in confirmation with earlier workers. Das and Mahanta (1985), as well as Patel (1988) reported Bavistin effective against the growth of P. palmarum and P. mangiferae, respectively. Khalequzamman et al. (2003) observed that among six fungicides, Bavistin 50% WP (carbendazim) 0.1% found better in controlling leaf spot of sapota caused by Pestalotia sapotae. Bavistin 50% WP (carbendazim), copper oxychloride and carbendazim 12%+mancozeb 63% were completely inhibitory to Pestalotiopsis sp. (Pandey et al., 2006; Rokade, 2009).

Conclusion

Among all the fungicides tested in vivo against grey leaf blight of mango, carbendazim 12%+mancozeb 63% (0.2% @ 2.0 g l^-1) was found significantly superior with minimum grey leaf blight intensity followed by kresoxim methyl 43% SC (0.1% @ 1.0 ml l^-1). Copper oxychloride 50% WP (0.2% @ 2.0 g l^-1) was found to be the next best treatment in order of effectiveness which was at par with cymoxanil 8%+mancozeb 64% (0.2% @ 2.0 g l^-1).

Acknowledgement

The authors express their gratitude to The Director of research, Dean P.G. Studies, Navsari Agricultural University, Navsari, Gujarat for providing necessary facilities during the present investigations. Authors are also thankful to ITCC. IARI, New Delhi for identification of the pathogen.

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