Blackgram leaf crinkle virus and Blackgram leaf curl virus

Systematic position, Symptoms, IDM

1. Blackgram leaf crinkle virus and Blackgram leaf curl virus COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), ViaVaigai Dam, Theni-625 562 STUDENT Miss. KAVIYA R ID. No. 2015021058 COURSE TEACHER Dr. PARTHASARATHY S Asst. Professor (Plant Pathology)

2. Blackgram leaf crinkle virus Blackgram leaf crinkle virus causes Blackgram leaf crinkle disease/ Urdbean leaf crinkle disease. Urdbean ( Vigna mungo L. Hepper ) is more susceptible than other pulses to leaf crinkle disease.

3. History: First reported in Vigna mungo from the Pantnagar District, Nainital , India by Sharad Chandra J Kolte and Dr.Yeshwant Laxman Nene (1972). They found that the first recognizable symptoms, under field conditions, usually appear 3 weeks after sowing of black gram with seedborne infection.

4. . Geographical distribution : Spreads in India ©Plantwise.org

5. Systematic position: Group : II Order : (+) ss DNA viruses Family : Geminiviridae Genus : Begomovirus Species : Urdbean leaf crinkle virus (ULCV)

6. Significance : Urdbean leaf crinkle disease (ULCD) is an economically significant widespread and devastating disease resulting in extreme crinkling, puckering and rugosity of leaves.

7. It inflicts heavy yield losses annually in major Urdbean -producing countries of the world. The loss in seed yield in ULCD-affected Urdbean crop ranges from 35 to 81% , which is dependent upon type of genotype location and infection time .

8. Host plants / species affected: Vigna mungo (Black gram) Cajanus cajan (Pigeon pea) Cucumis sativus (Cucumber) Lablab purpureus (Hyacinth bean) Phaseolus lathyroides ( Phasey bean) Phaseolus vulgaris (Common bean) Ricinus communis (Castor bean) Vigna aconitifolia (Moth beans) Vigna radiata ( Mung bean) Vigna unguiculata (Cowpea)

9. Symptoms/signs Inflorescence   -  twisting and distortion Leaves   -  abnormal forms Whole plant    -  dwarfing

10. s The disease usually attacks black gram in all seasons. Characterized by enlargement of leaves followed by crinkled surface of leaf lamina . The crinkling is more on younger leaves. Flowering is delayed by 8-10 days. Inflorescence turns bushy in appearance. Pod setting is curtailed which decreases the yield drastically.

11. Blackgram leaf crinkle virus symptom © AGRIORISSA Vector : whitefly

12. Survival & Favourable Conditions The virus is seed transmitted. Whiteflies, Aphids and Henosepilachna beetles also transmit the disease. The virus is also transmitted through sap inoculation, grafting.

13. INTEGRATED DISEASE MANAGEMENT : Cultural Control : The crop must be sown timely. The spacing between the lines should be maintained at 30 to 40 cm. Only certified seeds should be used for sowing.

14. In endemic areas only tolerant and resistant varieties should be used. Weeds plants should be rouged out at their inception. Insect, fungal and nematode vectors should be controlled using suitable pesticides.

15. Control white fly as it spreads the virus. Grow resistant varieties like ADT-3. Removal and quick burning of the infected plant.

16. Chemical Control: Seed-borne infection can be eliminated by hot water treatment of seed at 55°C for 30 minutes.               Spraying insecticides 3 weeks after sowing control pests.

17. Blackgram leaf curl virus Systematic position: Group : V (-) ss RNA virus Order : Mononegavirales Family : Bunyaviridae Genus : Tospoviridae Species : Tomato spotted wilt virus (TSWV)

18. Damage  : A potential killer of black gram plants, more severe in Kharif season. The earliest symptoms appear on youngest leaves as chlorosis around lateral veins and its branches near the margin.

19. The leaves show curling of margin downwards. Some of the leaves show twisting. The veins show reddish brown discolouration on the under surface which also extends to the petiole.

20. Plants showing symptoms within 5 weeks after sowing invariably remain stunted and majority of these die due to top necrosis within a week or two. Plants infected in late stages of growth do not show severe curling and twisting of the leaves but show conspicuous venial chlorosis any where on the leaf lamina.

21. Blackgram leaf curl virus – symptom © ©AGRIORISSA Vector: Scirtothrips dorsalis

22. Mode of spread: The disease develops in the fields mainly through seed or rubbing of diseased leaves with the healthy ones. INTEGRATED DISEASE MANAGEMENT: Cultural Control: Timely sowing. Complete field and crop sanitation. Take control measures for thrips .

23. Chemical Control: The virus is transmitted by thrips - Scirtothrips dorsalis , and controlling thrips by spraying 1 g Acephate or 2 ml Dimethoate per litre .

24. REFERENCES : AGRIORISSA – Blackgram ( Urad dal ) Diseases. Beniwal.S.P.S and Y.L. Nene, 1983, Plant Viruses Online - Urdbean leaf crinkle virus .