Evaluation of Different Treatments on the Management of Black Gram Powdery Mildew Disease Caused by Erysiphe polygoni (De Candolle)

Black gram ( Vigna mungo L.), is one of the most important short duration pulse crops grown in India. Powdery mildew caused by Erysiphe polygoni is a major destructive disease causing drastic economic yield loss upto 50 per cent. In this present study to evaluation of different treatments on the management of powdery mildew on Black gram. Among five mangrove species tested, the leaf extract of Rhiphora apiculata out performed well recording maximum inhibition of conidial germination. In case of fungicides, Azoxystrobin @ 0.1% significantly reduced the conidial germination. The bio-agent Ampelomyces quisqualis was found to be effective at 0.5 per cent concentration against the pathogen. The susceptible variety ADT-3 was raised in both pot and field for management practices. The treatment involving combination of bio-agent and botanical i.e., foliar spraying of A. quisqualis @ 0.5% on 43 DAS AND 53 DAS + foliar spraying of R. apiculata @ 15% on 43 DAS+ 53 DAS recorded minimum per cent disease index in both pot (18.94 %) and field trial (14.50%). The synergistic effect of A. quisqualis and R. apiculata significantly reduces the disease incidence and considerably improve the biometric of blackgram in both pot and field trials are approximately equal to fungicide application.


Introduction
Black gram (Vigna mungo L.) is one of the most important short-duration pulse crops grown in India.The pulse 'Black gram' plays an important role in the Indian diet, as it contains a high amount of protein and it is a supplement to a cereal-based diet.The green pods are eaten as a vegetable and they are highly nutritious.Black gram is rich in easily digestible protein 25.21 per cent, contains about 58 per cent of carbohydrate, 2 per cent of fat, 0.273 mg of vitamin B1, 0.254 mg of vitamin B2, 1.447 mg of Vitamin Niacin, 138 mg of calcium, 379 mg of phosphorus, 7.57 mg of iron per 100 gram of seeds (USDA National Nutrient base).Since it serves as a cheaper source of protein for the poor, it is rightly called the "Poor man's meat" and can also be used as green manure.
Black gram originated from South Asia, later it has been in cultivation in many parts of Asia, Australia, West Indies, South and North America, and tropical and subtropical Africa.In India, it is primarily grown in Madhya Pradesh, Maharashtra, Orissa, Andhra Pradesh, Uttar Pradesh, and Tamil Nadu.Asia alone contributes about 90% of the world's total black gram production.In India, black gram is cultivated around an area of 4.6 m ha with a total production of 24.5 lakh t and productivity of 543 kg ha -1 whereas, in Tamil Nadu, it holds an area of 3.7 lakh ha with a production of 2.7 lakh t and productivity of 650 kg / ha. 1 In the case of its vast growing area and production, its productivity is low due to various biotic and abiotic stresses. 2Among all the fungal diseases, powdery mildew caused by Erysiphe polygoni is the major one.The pathogen was reported by de Candolle and found to be one of the most economically important diseases in black gram which occurs at the later stages of the crop growth causing high yield loss.
Powdery mildew is usually noticed in 45 days old crops in black gram. 3In the powdery mildew disease white, powdery patches appear on leaves and other green parts and later become dull in color.These patches gradually increase in size and become circular, covering the lower surfaces as well.Severely affected parts become shriveled and distorted.In severe infections, the foliage turns yellow, causing premature defoliation.Powdery mildew results in qualitative and quantitative loss of grains.The reduction in photosynthetic activity and physiological changes takes place leading to 40-90% yield loss depending on the stage and the occurrence of the disease. 4ny systemic and non-systemic fungicides were reported to manage the powdery mildew of black gram.However, the application of chemicals causes environmental pollution and is injurious to the soil ecosystem.The information on the efficacy of new generation fungicide, botanical and organic amendment against powdery mildew of black gram is insufficient.Hence bio-control agents and botanicals are used against E. polygoni.
In the present study to screening the efficacy of different treatments to management of black gram powdery mildew under pot and field trial.

Materials And Methods Experimental Details
Management practices were carried out against E. polygoni in black gram variety ADT-3.The leaf extract and A. quisqualis were prepared as per the recommended dosage.The treatments were sprayed on all aerial parts of the plant using a hand sprayer.The first spraying was taken up before the initial appearance of the disease in the crop i.e., 43 DAS and further spray was given at 10 days intervals on 53 DAS. 2 The pot trial and field trial was conducted with nine treatments including control.The cultivation practices have been carried out following righteous procedures uniformly.

Statistical Analysis
Statistical evaluation was done using the analysis of variance (ANOVA) followed by the Duncan's Multiple Range Test (DMRT).The statistical significance was expressed at p≥ 0.05.Here we used Replicator software and Wasp software for statistical analysis.

Result and Discussion Evaluation of Different Treatments on Management of Black Gram Powdery Mildew Disease (Pot Trial & Field Trial)
A pot trial was conducted to evaluate the efficacy of bio-agents, botanicals and fungicides against powdery mildew of black gram during 2022 with bio-agent, botanical and a fungicide.Observations on per cent disease index was recorded.In the present investigation, Azoxystrobin 25% SC @ 0.1 % was found to be effective against E. polygoni.
The fungicide recorded PDI of 19.30 per cent after 1 st spray and 9.37 per cent after 2 nd spray followed by foliar application of A. quisqualis @ 0.5% on 43 DAS + A. quisqualis @ 0.5% on 53 DAS + R. apiculata @ 15% on 43 DAS + R. apiculata @ 15% on 53 DAS with PDI 23.25 per cent after 1st spray and 14.63 per cent after 2nd spray.The untreated plants showed higher PDI of 51.76 per cent to 67.47 per cent (Table 1).
T 1 : Ampelomyces quisqualis @ 0.5% on 43 DAS T 2 : Ampelomyces quisqualis @ 0.5% on 53 DAS T 3 : Rhizophora apiculata @ 15 ml on 43 DAS T 4 : Rhizophora apiculata @ 15 ml on 53 DAS T 5 : T 1 + T 2 T 6 : T 3 + T 4 T 7 : T 5 + T 6 T 8 : Azoxystrobin @ 0.1% T 9 : Control Since, Azoxystrobin is effective against powdery mildew disease, it is used as standard check for further studies.In case of compatibility, in vitro study is tedious since it is an obligate parasite.Hence, field study was carried out and both bio agent and botanical were found to be compatible as they showed significant better result in combined application than individual.

Observations on Powdery Mildew Incidence
Observations were made on the prevalence and severity of powdery mildew at different stages to record the prevalence of disease after 1 st spray and 2 nd spray.A field trial was conducted to evaluate the efficacy of bio-agents, botanicals and fungicides against powdery mildew of black gram during 2022 with bio-agent, botanical and a fungicide.Observations on per cent disease index was recorded.In the present investigation, Azoxystrobin 25% SC @ 0.1 % was found to be effective against E. polygoni.The fungicide recorded PDI of 15.50 per cent after 1 st spray and 6.98 per cent after 2 nd spray followed by foliar application of A. quisqualis @ 0.5% on 43 DAS + A. quisqualis @ 0.5% on 53 DAS+ R. apiculata @ 15% on 43 DAS+ R. apiculata @ 15% on 53 DAS with PDI 19.95 per cent after 1st spray and 9.06 per cent after 2nd spray.The untreated plants showed higher PDI of 48.17 per cent to 64.37 per cent (Table 2).An experiment was conducted to assess the efficacy of bio-control agent, botanical and a fungicide. 2he mean per cent disease incidence ranged from 15.80 to 47.70 in different treatments.The maximum reduction of disease incidence was recorded in wettable sulphur 0.25% (15.80%) followed by carbendazim 0.1% (58.91%) and castor oil 1% with A. quisqualis (48.53 per cent).

Conclusion
Among the various treatments tested, Azoxystrobin 25% SC @ 0.1 % was found to be effective against E. polygoni in both pot and field trial.However, the synergistic effect of A. quisqualis and R. apiculata was significantly reduced the disease incidence and considerably improve the biometric of blackgram.Thus, it may be consider as an effective bioproduct for the successful management of blackgram powdery mildew disease for future concern instead toxic chemical pesticides.