Black Shank Of Shank

symptoms,pathogen and management

1. BLACK SHANK OF TOBACCO STUDENT COURSE TEACHER MODHANA. V Dr. Parthasarathy . S 2016021021 Asst.Prof ., (Plant Pathology)

2. Disease name: Black Shank of Tobacco Pathogen name : Phytophthora nicotianae Breda de Haan Hosts: Tobacco: Nicotiana tabacum and Nicotiana rustica

3. Systematic position Kingdom: Chromista Phylum: Heterokontophyta Class: Oomycota Order: Peronosporales Family:Peronosporales Genus: Phytophthora Species: P. nicotianae

4. Significance Black shank is among the most destructive and widespread of all tobacco diseases in North Carolina It is a devastating root rot disease caused by the oomycete pathogen

5. HISTORY Black shank first appeared in the United States in 1915. It was first repored in North Carolina in Forsyth country.

6. Distribution In world USA, Dutch East Indies and Puerto Rico . In India All the tobacco growing states Andhra Pradesh Tamil Nadu Gujarat and UP.

7. SYMPTOMS Black shank can affect any part of the tobacco plant at any growth stage. Root and crown rot are the most common symptoms. It causes rapid yellowing, wilting of leaves and eventually plant death.

8. Leaf spots appear and form circular, yellowish-to-brown lesions upto 3 inches in diameter with concentric rings. A dark brown to black lesion often appears on the stalk. When cut open, the lower stem and crown often show blacken pith with distinct disk and white hyphae . The chlorophyll content of the infected plants will reduced

9. In leaves and causes blighting and drying of the bottom leaves. A longitudinal cut through the stem reveals necrotic pith that is often separated into disks   Infected roots are initially water-soaked, lesion then rapidly become necrotic spreads to stem causing black shank

10. Leaf spots caused by P. nicotianae content. ces . ncsu . edu

11. Stem infection caused by P. nicotianae crosscreekseed . com

12. Plant affected by Black shank tobacco-diseases. info

13. Field affected by Black shank knowmoregrow . com

14. Pathogen Characters Hyphae : It is colourless and transparent. They lack internal partitions, or septa. Hyphae are also coenocytic . It has numerous hyphal swelling, and highly branched. Mycelium: It is intercellular, branched, coenocytic , hyaline and non- septate .

15. Hyphae en. wikipedia . org

16. ASEXUAL REPRODUCTION P.nicotianae primarily reproduces asexually through the formation of several types of structures. Chlamydospores : It is asexual, thick-walled spores produced at the tips or in the middle of hyphae . It serve as the primary survival propagule and as the primary inoculum that initiates epidemics. Survival for 4 to 6 years in soil has been reported.

17. Zoospores: It is typically kidney –shaped, with a ventral. Groove from which two flagella emerge. The posterior flagellum is whip-like and the anterior flagellum a tinsel type, is shorter with hairs along its length. Zoospores emerge from sporangia and swim through soil water. It encyst and a single germ tube emerges from the spores.

18. Sporangia: It can be ovoid, pear-shaped, or spherical. It have very prominent tips called papillae. Sporangia may sometimes directly produce hyphae , but more often form zoospores. The number of zoospores produced by a single sporangium is typically 5-30.

19. Chlamydospores Zoospores en. wikipedia . org

20. Sporangia en. wikipedia . org

21. SEXUAL REPRODUCTION Oospores: It are thick-walled . The oospore germinates by producing a germ tube. It serve as a primary survival propagule or initiate infections that lead to epidemic development.

22. Oospores en. wikipedia . org

23. Life cycle of P. nicotianae en. wikipedia . org

24. MODE OF SPREAD PRIMARY SPREAD: It is a soil borne disease. The fungi survives on plant residues in soil. The primary infection takes place in optimum weather conditions by means of soil - inoculum .

25. SECONDARY SPREAD : The spread of diseases takes place by means of zoospores which are disseminated by wind, water and other suitable agencies .

26. FAVOURABLE CONDITION The organisms can grow vegetatively at temperatures between 5 ° C and 37 ° C. Extended exposure to temperature above 40 ° C Is lethal to the organism. Disease is favoured by Ph value is greater than 6.2.

27. Management Cultural pratices It includes raising the beds, crop rotation and by doing stalk and root destruction. Co Cover the seed beds with paddy husk or groundnut shell at 15-20 cm thick layer and burn. Select health, disease free seedlings for transplanting.

28. Chemical control: The use of soil fumigants such as chloropicrin may reduce pathogen populations. Application of fumigant nematicide such as 1,3- dichloropropene reduce nematode populations that enhance black shank incidence and severity.

29. Provide adequate drainage in the nursery. Drench the nursery beds with 1% Bordeaux mixture or 0.2% Copper oxychloride , two days before sowing. Spray the beds two weeks after sowing with 0.2 per cent Metalaxyl or 0.2 per cent Copper oxychloride or 1 per cent Boreaux mixture and repeat after 10 days.

30. REFERENCE Singh,R.S.,2018.Plant Diseases.Tenth Edition.Scientific International( Pvt )Ltd. New Delhi. Sushil Kumar Singh.,Dinesh Kumar and Adesh Kumar.2015.Plant Diseases And Their Management.Kalyani Publisher. New Delhi.