Web blight of mungbean

Study based presentation for research scholars and students of Agriculture and Plant Pathology

1. WELCOME WELCOME

2. Presented by: Rinku Bhaskar M. Sc.(Ag.)Plant Pathology, 2 nd year, Id No- A-11758/20 On Submitted To: Dr. S.N. Rahul Assistant Professor Department of Plant Pathology Acharya Narendra Deva University of Agriculture & Technology Kumarganj Ayodhya U.P India 224229 Course Seminar : PP-591 “Web Blight : A Devasting Disease Of Mungbean.”

3. Introduction . Nutritional value and its uses. Web blight pathogen and taxonomy. Why it’s called Web blight. Symptoms on differents parts of host. Characteristics of pathogen. Host range (Anastomosis groups). Web blight management options. (cultural, chemical and biological ). Integrated management of web blight. Future directions . Content

4. Introduction Mung bean [ Vigina radiata: (L) Wilczek] is a short duration, Kharif and Zaid season, diploid (2n = 2X = 22) self-pollinating legume. It is an important dietary source of protein and other essential nutrients in South and West Asia, North and East Africa. It is an important pulse crop originated from India and central Asia. India is the largest producer with more than 50% of world. China produces large amounts of Mung beans, which represents 19% of its legume production. Mung bean production is mainly (90%) situated in Asia. Though it is produced in many African countries but the Mung bean is not a major crop there ( Mogots , 2006). It is mainly grown in Rajasthan, Madhya Pradesh, Punjab, Tamilnadu, Karnataka, Andhra Pradesh, Uttar Pradesh, Bihar and Orissa. Green gram (Mungbean) output accounts for about 10-12% of total pulse production in India.

5. In 1924, web blight was reported for the first time on mungbean from Philippines ( Nacien , 1924). While in India , Dwivedi and Saksena (1974) first reported it in mungbean from Kanpur , Uttar Pradesh. Further, it has also been reported from Assam ( Saikia , 1976), Punjab (Bains et al., 1988), Madhya Pradesh (Tiwari and Khare , 1998), Bihar, Rajsthan , Haryana , Himachal Pradesh and Jammu & Kashmir (Anonymous, 2004). The pathogen causes huge losses in Yeild of mungbean and urdbean in India (Dubey , 2003). In warm and humid tropic zones of the world , web blight of mungbean is one of the major serious disease in its production and causes heavy Yeild losses approximately 35-40 % (Gupta et al., 2010).

6. A. Sprouts B. Whole grains C. Spilited grains (Dal) Uses Of Mungbeans

7. It is an important dietary source of protein and other essential nutrients in South and West Asia, North and East Africa. Boosts Blood Cerculation Helps Prevent Diabetes

8. Order Family Species Taxonomy Source: AG-1 (B) Genus

9. Why it’s called Web Blight. The fungus infects all above ground parts of the plant i.e. leaves, petioles, stem and pods but most destructive is on foliage. Symptoms on leaves appear as initial small circular brown spots. These spots enlarge and are surrounded by water soaked areas. The lesion expands and collapses and white fungal growth may be seen on the lower surface of leaves and young branches. The mycelium on infected leaves appears as spider web, thus, called as Web blight'.

10. Symptoms of Rhizoctonia on seedlings The pathogen may cause seedling mortality and collar rot when infection occurs on collar region as reddish brown lesions which soon girdles the basal portion of stem. At this point seedling wilts and collapses and called as collar rot (Dwivedi and Saksena , 1974).

11. Symptoms of Rhizoctonia solani on leaves Lesion on stem and petioles generally appears when infected plants have lost many of their infected leaves or after they have been completely defoliated. Lesions on stem and petiole are linear to oval and reddish brown in appearance. White brown sclerotia are produced abundantly on infected stem and petioles. The affected parts shriveled, dry and finally premature defoliation of affected plant parts may be observed. The leaf canopy is completely destroyed and in severe cases, affected plants die prematurely before flowering and pod formation. Spots on young pods are light tan and irregular in shape but on mature pods they are dark brown and sunken.

12. Different symptoms of Web Blight on different parts of plant.

13. The primary infection of disease comes through seeds, soil and naturally infected hosts. Secondary spread of the disease is due to basidiospore and contact between diseased and healthy plants (Ratan and Dwivedi, 1998). DISEASE CYCLE OF WEB BLIGHT

14. Characteristics of pathogen. The hyphae of Rhizoctonia solani are initially hyaline but later brown and are characteristically branched. The branches arise at right angles (90%) from below the septa and show distinct constriction of the point of origin under microscope. Light to dark brown sclcrotia are abundantly forms on infected surface at the periphery ( Alexopolas , 1996 and Dubey , 2003). The perfect stage of R. solani has been reported by Dwivedi and Saksena (1974).

15. Anastomosis Group Concept in R. solani Rhizoctonia solani is a plant pathogenic fungus commonly found around the world. It is a soil and seed borne Deuteromycetes causing blight, on many economically important crops. The perfect stage of Rhizoctonia solani, Thanetophorus cucumeris belongs to class Basidiomycetes Successful anastomosis indicated that the isolates were genetically similar while, unsuccessful anastomosis indicated that they were dissimilar and distinct. As a result Rhizoctonia solani has been split into at least 13 different “Anastomosis groups”(AGs) and some sub groups. The Sclerotia of R. solani survive in a dormant stage in the soil for several years and germinates again in favorable environment, and can transmit to other individuals through physical contact. Rhizoctonia solani infects its host and causes Damping off and Root rot at seedling stage and Blightining in foliage through the infection in seed

16. Host range of Rhizoctonia solani The host range of Rhizoctonia solani is wide and it causes various diseases on important crop plants of the world including species in Solanaceae , Fabaceae and Poaceae etc. Disease symptoms including leaf blight, leaf spots, damping off, rots on roots , shoots and fruits, canker lesion on sprouts and stolons , sclerotial diseases. Rhizoctonia solani J.G. Kuhn has a significant economic impact in the development and production of a wide variety of diseases in different crops. It is considered a complex species because its physiological and pathogenic variability. Disease symptoms and host range of different Anastomosis groups (AGs) of Rhizoctonia solani is given below.

17. Anastomosis group Symptoms Host crop Reference AG 1 Sheath blight Rice Sayler and Yang 2007 Web blight Common beans Muyolo et al. 1993 Bud rot Soyabean Hwang et al. 1996 AG 2 Root rot Sugarbeet Herr 1996 Stem canker Potato Chand and Logan 1983 Sheath blight Rice Hashiba and Kobayashi 1996 Leaf blight Sugarbeet Herr 1996 Damping off Soyabean Nelson et al. 1996 AG 3 Leason on roots Soyabean Nelson et al. 1996

18. Anastomosis group Symptoms Host crop Reference AG4 Stem canker Potato Anguiz and Martin 1989 Fruit rot Tomato Strahnov et al. 1985 Root rot Soyabean Lilu and Sinclair 1991 Root rot Wheat Rush et al. 1994 Root rot Pea Hwang et al. 2007 Root rot Common bean Muyolo et al. 1993 Root rot Cotton Rothrock 1996 AG5 Stem canker Potato Bandy et al. 1984 Root rot Soyabean Nelson et al. 1996 Root rot Barley Rush et al. 1994

19. Anastomosis group Symptoms Host crop Reference AG 6 Mycorrhizal Carling et al. 1999 AG 7 Root canker Cotton Baird and Carling 1997 AG 8 Bare patch Cereals Mazzola et al. 1996 AG 9 Minor pathogen Potato Carling et al. 1994 AG 10 Minor pathogen Lupin MacNish et al. 1995 AG 11 Non pathogenic Eken and Demirci 2004 AG 12 Mycorrhizal Cotton Carling et al. 1999 AG 13 Minor pathogen Carling et al. 2002 a

20. IDM IDM refers to a decision based process involving coordinated use of multiple tactics for optimizing the control of pathogen in an ecologically and economically. Biological control Web Blight management

21. Cultural practices Use of clean seed for sowing and use of fungicidal seed treatment and soil drenching can reduce contaminating inoculum sources. To prevent the crop from various diseases a proper depth (10–12 cm) of seed planting should be used. Intercropping/mixed cropping is being suggested with non host crop to reduced blight incidence and increased crop yield. Deep ploughing and removal of infected trash can reduce inoculum levels of web blight of mungbean. Soil solarization is another way to minimize the disease incidence. WHY IDM IDM is necessary to prevent these all problems. Resistance development in pathogen. New races or pathotype development. Residual toxicity in soil and food materials. Environmental pollution.

22. Use of clean seed Soil Solarization Intercropping Sowing at a proper depth Removal of trash Different Cultural Practices

23. The varietal resistance is a major goal of mungbean improvement programme currently running at the All India Cordinated Research Project on MULLaRP . In order to identify the resistant variety of Web Blight, screening under field and controlled conditions (green house and laboratory conditions) has been suggested. Web blight sick plot is the most common method used to screen disease resistant plants under natural conditions. The advantage of this method is that, large number of genotypes can be screened. After multiplication of fungus on sorghum grains, inoculums were placed in each row before 15 days of sowing. Wild species are an invaluable source for disease resistance. In India, many web blight resistant varieties are released such as ‘Pusa-1771’, ‘Pusa-1371’, ‘Pusa-1431’ and K-2328 Web blight resistant cultivars

24. Biological control is known to be the best and effective method, against soil-borne pathogens. This method has many advantages such as environment friendly, cost effective and extended plant protection. Many fungal and bacterial species like Pseudomonas , Trichoderma and Streptomyces have antagonistic effect on Fusarium wilt of lentil. Among them Trichoderma species are been extensively used as bio-control agent against soil and seed-borne diseases. A study revealed that the (seed treatment with Gliocladium virens + P. fluorescens ) or ( Bacillus subtilis + T. harzianum / T. viride / G. virens) have been found more effective in controlling Web blight incidence in Mungbean. In the recent study, two species of Trichoderma were employed against Rhizoctonia solani responsible for web blight of mungbean. The results revealed that T. harzianum was highly effective in controlling web light disease in comparison to T. viride , when applied as a soil drench. Biological control

25. Seed Treatment Mungbean Seed Bacillus subtilis Trichoderma

26. Several fungicides have been tested against the web blight in different parts of the world. The study reveals that the systemic fungicides found to be superior to non-systemic fungicides in inhibiting the fungal mycelial growth in plates as well as in pot seed treatment ( Naik et al ., 2017 ) Shailbala and H.S Tripathi 2010 reported that propiconazole (0.1%) applied as prophylactic spray at 10 day interval resulted the lowest disease severity (32.03%), highest grain yield (880 kg/ha & maximum thousand grain weight (35.5 g) followed by carbendazim (0.1%), mancozeb (0.25%) sprayed plots, respectively. Chemical control

27. Conclusion Web blight is a devasting disease of mungbean on the bases of disease severity and yield losses because it causes 35-40 % yield losses of its production. So control measure should be applied at proper time and management should be ecofriendly and cost effective. There are lot of plant extracts, bioagents and resistant cultivars besides chemicals to manage web blight disease like plant extract ( Garlic and Ginger extract), Bio-agents ( Trichoderma harzianum, Trichoderma viride, Bacillus subtilis, Bacillus fluorescence ). In India, many web blight resistant varieties are released such as ‘Pusa-1771’, ‘Pusa-1371’, ‘Pusa-1431’ and K-2328.