This powerpoint consist of basic information required to study about Bean Common Mosaic for Bsc.Agriculture and plant pathology.

1. Manila Lamichhane
manila01lc@gmail.com
BEAN COMMON MOSAIC

2. 01
02
03
Economic loss varies from
30% to 100%
04
Facts
First observed nearly 100 years
ago in Russia
Epidemics have become
sporadic since 1930s
Disease is present throughout
the world

3. Bean common mosaic
Causative organism:
•Bean common mosaic virus.
•Member of potyvirus (Potato virus Y) i.e. largest single group of plant
virus that cause economic damage.
•Virus is obligate parasite.
•Infection is systemic.
Survival and spread:
•Seed borne and pollen borne.
•Mechanical means of transmission(rubbing).
•Can be transmitted to other legume crops.

4. Symptoms:
Three principle symptoms:
A.Mosaic
B. Black root(systemic necrosis)
C.Local leaf lesion

5. Mosaic is the symptom most commonly associated with bean common mosaic virus.
Distinct or diffuse zones of light- and dark- green tissue are typical.

6. Black root occurs when certain strains of bean common mosaic virus infect beans
containing the I gene . All plant stages from seedling to mature plant may be affected.
Plant die soon after infection.

7. Cross section of bean pod and root revealed darkened vascular tissue in the black root
reaction.

8. Vein banding and leaf cupping and rolling is commonly seen in bean common mosaic
virus infections.

9. Local lesions, also known as road mapping or veinal necrosis, may develop at the
inoculation site of bean common mosaic virus.

10. False symptom:
•Stunting, leaf rolling and cupping are common symptoms of BCM, but they
may also be caused by several other factors.
•Bean yellow mosaic virus and beet curly top virus may cause leaf cupping.
•Cupping is generally more pronounced in older leaves infected with bean
yellow mosaic virus.
•Younger leaves are more severely cupped in beet curly top virus infections.
•Phenoxy herbicides may also cause plant distortion that may be confused
with BCM.

11. Etiology:
•Bean common mosaic virus (BCMV) is flexous
•720*12 nm, contains 95% protein and 5%ssRNA

12. Disease cycle:
•Primary source of inoculums from infected seed or from
nearby infected crops
•Secondary spread of the disease by vectors.
•Aphid (Aphis fabae, Acyrthosiphon pisum, Myzus
persicae) transmits the mosaic virus in non persistent
manner from diseased to healthy plant.
•Its also transmitted to new plants through pollen
•Mechanical mode of transmission (rubbing)
•Seed transmission is not known to I gene varieties.

13. Management :
•Use certified seeds
•Early planting escape high insect population.
•Intercropping with maize hinder insect activities.
•Resistant varieties should be encouraged.
•Aphid transmit BCMV non persistently so use systemic insecticide.
Seeds Percent tolerance
Foundation seed 0.0
Registered seed 0.5
Certified seed 1.0

14. Reference:
Bean Common Mosaic Virus,(PNW 358) Robert
L. Forster, James R. Meyers and Phillip H. Berger,
Jan 1991
http://www.google.com

15. Thank you