Research Paper | Chemical management of marssonina leaf blotch and alternaria leaf spot diseases of apple in Himachal Pradesh

Research Paper | Chemical management of marssonina leaf blotch and alternaria leaf spot diseases of apple in Himachal Pradesh

Shalini Verma and Kishore Khosla

Shalini Verma
Department of Plant Pathology, Dr. YS Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India
Kishore Khosla
Regional Horticultural Research and Training Station, Dr. YS Parmar University of Horticulture and Forestry, Seobag-Kullu, Himachal Pradesh, India

P-ISSN: 2349–8528 E-ISSN: 2321–4902
IJCS 2018; 6(4): 3316-3319
© 2018 IJCS
Received: 09-05-2018
Accepted: 17-06-2018


Abstract

A number of leaf spot diseases attack apple, the most important temperate fruit crop in Himachal Pradesh. After the scab caused by Venturia inaequalis (Cooke) G. Winter, apple plantations in the state are under attack by relatively less known fungal pathogens Marssonina coronaria (Ellis & J.J. Davis) J.J. Davis (Syn. Marssonina mali (P. Henn) Ito) and Alternaria alternata (Fr.) Keissler by causing mid-season defoliation. Hence, to manage these diseases, fluopyram 200 + tebuconazole 200 SC along with standard checks were evaluated for bio-efficacy against Marssonina blotch and Alternaria leaf spot during 2015 and 2016. The pooled analysis of two crop seasons showed that all the treatments differed significantly with regard to per cent disease index and per cent disease control for both the diseases. For Marssonina blotch, maximum per cent disease control was observed when the crop was sprayed with fluopyram 200 + tebuconazole 200 SC at a concentration of 0.0625 per cent (94.35%) followed by fluopyram 200 + tebuconazole 200 SC at a concentration of 0.05 per cent (89.85%) and 0.0375 per cent (87.72%), respectively. For Alternaria leaf spot, maximum per cent disease control occurred when the crop was sprayed with fluopyram 200 + tebuconazole 200 SC at a concentration of 0.0625 per cent (94.55 %) followed by fluopyram 200 + tebuconazole 200 SC at its concentration 0.05 per cent (89.42%) and 0.0375 per cent (86.55 %), respectively.

 

Materials and Methods
The present studies for evaluation of effective fungicides against Marssonina blotch and Alternaria leaf spot were undertaken at the Regional Horticultural Research and Training Station, Seobag- Kullu, Himachal Pradesh, India during the years 2015 and 2016 under natural epiphytotic conditions. The field experiments were laid out in Randomized Block Design with seven treatments including control (water spray) and each treatment was replicated thrice. The fungicides used were fluopyram 200 + tebuconazole 200 SC (0.0375, 0.05 and 0.0625 %), fluopyram 500 SC (0.025 %), tebuconazole 250 EC (0.05 %), difenoconazole 25% EC (0.015 %), and mancozeb 75% WP (0.3 %). The first spray of different fungicides was given in the last week of May on apple trees and the remaining three sprays were given at 15 days interval. The observations on the disease severity on apple leaves were recorded at 15 days after the last spray on hundred leaves collected at random from all the four sides of the trees.

 

The disease severity for Marssonina blotch was recorded by using the scale given by James (1974) [6], the details of the scale are as follows:

The disease severity for Alternaria leaf spot in apple was recorded by adopting the 0-9 disease rating scale as given below:

0 = No leaf fall; all leaves healthy
1 = No leaf fall; 10-15 leaves showing 1-2 spots with or without yellowing in the lower canopy of the tree
2 = Leaf fall initiated but less than 10 %; and up to 25 % of the remaining leaves showing disease symptoms
3 = Leaf fall up to 25 %, rest showing leaf spotting and/or yellowing
4 = Leaf fall up to 33% and the remaining >50 per cent leaves showing disease symptoms i.e. leaf spotting and/or yellowing
5 = Leaf fall up to 50 % and remaining 25% of the leaves showing symptoms
6 = Leaf fall up to 66 % and remaining 25 % of the leaves showing symptoms
7 = Leaf fall up to 75 % and most of the remaining leaves showing symptoms
8 = Leaf fall up to 90 % and most of the remaining leaves showing symptoms
9 = Leaf fall more than 90 % and most of the remaining leaves showing symptoms

 

Results and Discussion

Bio-efficacy of different fungicides against Marssonina blotch

The pooled analysis of 2015 and 2016 crop seasons of data (Table 1) showed that all the treatments differed significantly with regard to per cent disease index and per cent disease control. Minimum per cent disease index occurred when the apple crop was sprayed with fluopyram 200 + tebuconazole 200 SC at a concentration of 0.0625 per cent (3.58 %). It was followed by fluopyram 200 + tebuconazole 200 SC at concentrations of 0.05 and 0.0375 per cent which provided 5.98 and 7.39 per cent control, respectively. The standard check fungicides viz., tebuconazole, fluopyram, difenoconazole and mancozeb when sprayed showed less per cent disease index of 7.34, 8.03, 8.51 and 8.53 per cent but was significantly less in comparison to control (64.43%).

Correspondingly, per cent disease control was maximum when the apple crop was sprayed with fluopyram 200 + tebuconazole 200 SC at a concentration of 0.0625 per cent (94.35 %) followed by fluopyram 200 + tebuconazole 200 SC at its concentration 0.05 and 0.0375 per cent which provided control of 89.85 and 87.72 per cent, respectively.
The standard check fungicides viz., tebuconazole, mancozeb, difenoconazole and fluopyram when sprayed showed per cent disease control of 90.70, 90.16, 88.68 and 86.88 per cent, respectively. Therefore, it is evident that all the sprays of different fungicides tested during 2015 and 2016 crop seasons were effective in controlling Marssonina blotch over control (water spray) but a new fungicide combination viz., fluopyram 200 + tebuconazole 200 SC at a concentration of 0.0625 per cent was more effective in field trials against the pathogen.

Earlier also many fungicides have been recommended for the management of leaf blotch of apple (M. coronaria), viz., Bordeaux mixture (2-12-100) + ZnSo4 (40g/20L), ferbam, zineb, folpet, captan, fuzet (Kwang and Chong, 1962) [8]; mancozeb, propineb, carbendazim (Sharma and Kaul, 1997) [16]; dodine (Sharma, 1999) [15]; dithiocarbamate, benzimidazole, and dithianon groups (Sharma and Bhardwaj, 2003 [14], Sharma et. al., 2004 [17]). Even the chemical control of A. mali has been achieved through use of fungicides such as iprodione, mancozeb, captan (Asari and Takahashi, 1988 [2]); polyoxin, captafol (Filajdac and Sutton, 1992) [4]; dodine, zineb, mancozeb + hexaconazole (Sharma et al., 2005) [19]; hexaconazole, copper oxychloride, ziram (Shahzad, 2009) [12]; and penconazole (Sofi et al., 2013) [20].
However, fluopyram acts on the mitochondrial respiration chain and is a potent source of broad-spectrum inhibition of fungal development. The fluopyram belongs to succinate dehydrogenase inhibitors (SDHIs) group of fungicides and has a systemic activity. It has excellent foliar activity against a wide range of significant pathogens. Resistance is an issue for the SDHIs and so the products are normally sold in mixtures (Oliver and Hewitt, 2014) [10]. Tebuconazole belongs to chemical group of triazoles and acts on the sterol biosynthesis in membrane [sterol biosynthesis inhibitor (SBI)
~ 3319 ~
International Journal of Chemical Studies
Class I]. It is systemic and provides protectant, curative and eradicant control (Oliver and Hewitt, 2014) [10].
Since the new combination of fluopyram 200 + tebuconazole 200 SC exhibits systemic activity and has different modes of action, therefore, such a new combination can delay or prevent the build-up of resistance in the pathogen and can be effectively utilized as a promising preventive fungicide for the control of both the leaf spot diseases of apple.

 

Bio-efficacy of different fungicides against alternaria leaf spot

The pooled analysis of 2015 and 2016 crop seasons of data (Table 2) showed that all the treatments differed significantly with regard to per cent disease index and per cent disease control. Minimum per cent disease index occurred when the apple crop was sprayed with fluopyram 200 + tebuconazole 200 SC at the concentration 0.0625 per cent (3.41%) followed by fluopyram 200 + tebuconazole 200 SC at its concentration 0.05 and 0.0375 per cent provided 5.71 and 7.46 per cent, respectively. The standard check fungicides viz., tebuconazole, fluopyram, difenoconazole and mancozeb when sprayed showed less per cent disease index of 8.24, 8.79, 11.84 and 17.75 per cent but was significantly less in comparison to control (57.97%). Similarly, maximum per cent disease control was observed when sprayed with fluopyram 200 + tebuconazole 200 SC at its concentration 0.0625 per cent (94.55 %). It was followed by fluopyram 200 + tebuconazole 200 SC at its concentration 0.05 and 0.0375 per cent at 89.42 and 86.55 per cent, respectively.
The standard check fungicides viz., tebuconazole, difenoconazole, fluopyram and mancozeb, when sprayed showed per cent disease control of 86.56, 84.86, 83.47 and 76.17 per cent, respectively. Therefore, it is evident that even though all the sprays of different fungicides tested during 2015 and 2016 crop seasons were effective in controlling Alternaria leaf spot over control (water spray) but a new fungicide combination viz., fluopyram 200 + tebuconazole 200 SC at a concentration of 0.0625 per cent was more effective in field trials against the pathogen.

Earlier also many fungicides have been recommended for the management of leaf blotch of apple (M. coronaria), viz., Bordeaux mixture (2-12-100) + ZnSo4 (40g/20L), ferbam, zineb, folpet, captan, fuzet (Kwang and Chong, 1962) [8]; mancozeb, propineb, carbendazim (Sharma and Kaul, 1997) [16]; dodine (Sharma, 1999) [15]; dithiocarbamate, benzimidazole, and dithianon groups (Sharma and Bhardwaj, 2003 [14], Sharma et. al., 2004 [17]). Even the chemical control of A. mali has been achieved through use of fungicides such as iprodione, mancozeb, captan (Asari and Takahashi, 1988 [2]); polyoxin, captafol (Filajdac and Sutton, 1992) [4]; dodine, zineb, mancozeb + hexaconazole (Sharma et al., 2005) [19]; hexaconazole, copper oxychloride, ziram (Shahzad, 2009) [12]; and penconazole (Sofi et al., 2013) [20].
However, fluopyram acts on the mitochondrial respiration chain and is a potent source of broad-spectrum inhibition of fungal development. The fluopyram belongs to succinate dehydrogenase inhibitors (SDHIs) group of fungicides and has a systemic activity. It has excellent foliar activity against a wide range of significant pathogens. Resistance is an issue for the SDHIs and so the products are normally sold in mixtures (Oliver and Hewitt, 2014) [10]. Tebuconazole belongs to chemical group of triazoles and acts on the sterol biosynthesis in membrane [sterol biosynthesis inhibitor (SBI)~ 3319 ~International Journal of Chemical Studies Class I].

It is systemic and provides protectant, curative and eradicant control (Oliver and Hewitt, 2014) [10].
Since the new combination of fluopyram 200 + tebuconazole 200 SC exhibits systemic activity and has different modes of action, therefore, such a new combination can delay or prevent the build-up of resistance in the pathogen and can be effectively utilized as a promising preventive fungicide for the control of both the leaf spot diseases of apple.

Conclusion
The results of our studies reveal that fluopyram 200 +tebuconazole 200 SC is a promising fungicide against the Marssonina blotch and Alternaria leaf spot diseases of apple in Himachal Pradesh. This combination at a concentration of 0.0625 per cent was highly effective and gave maximum per cent disease control in Marssonina blotch (94.35%) and Alternaria leaf spot (94.55%) in apple.

 

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