2. Presented by: Rinku Bhaskar
M. Sc.(Ag.)Plant Pathology, 2nd year,
Id No- A-11758/20
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. • 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.
Helps Prevent Diabetes
8. Fungi • Kingdom
Basidiomycotina • Division
Agricomycetes • Class
Cantharellales
Ceratobasidiaceae
Rhizoctonia
R. solani
•Order
•Family
•Species
Taxonomy
Source:
AG-1 (B)
Genus
9. •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. 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. 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.
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).
Symptom
development
Production of
sclerotia
Secondary
spread through
irrigation
water & rain
Pathogen
survive in soil,
seeds, crop
debris
asSclerotia and
dark mycelium
Infection in
root, stem or
leaf
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. 2002a
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.
IDM
components
Host
resistance
Cultural
control
Chemical
control
Physical
control
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.
1. Resistance development in pathogen.
2. New races or pathotype development.
3. Residual toxicity in soil and food materials.
4. 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
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.
