VERTICILLIUM WILT OF COTTON

SYMPTOMS, PATHOGEN, MANAGEMENT

1. COLLEGE OF AGRICULTURAL TECHNOLOGY ( Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), Via Vaigai dam , Theni -625 562 AA VERTICILLIUM WILT OF COTTON STUDENT COURSE TEACHER SIREESHA .N Dr. PARTHASARATHY .S ID.No.2016021042 Asst.Prof .,(Plant Pathology)

2. SIGNIFICANCE The world uses more cotton than any other fiber . Cotton is a leading cash crop in the U.S The production of each year’s crop involves the purchase of more than $5.3 billion worth of supplies and services.

3. Major disease in USA and USSR First reported in 1968- on hirsutum cottons in coimbatore , India The disease usually appears in November -December

4. ECONOMIC LOSSES: It causes about 10-15 percent loss on average. During 1980’s caused severe damage in Southern H igh plains and Texas.

5. DISTRIBUTION: World wide India Europe(wide spread) Tamil Nadu South Africa Maharastra Brazil Karnataka Canada Rajasthan

6. SYMPTOMS: The symptoms are seen when the crop is in squares and bolls . The first symptoms can be seen as bronzing of veins . It is followed by interveinal chlorosis and yellowing of leaves . Finally the leaves begin to dry, giving a scorched appearance . The drying of the leaf margins and areas between veins, which gives a Tiger stripe or Tiger claw appearance .

7. Infected stem and roots, when split open, show a pinkish discolouration of the woody tissue. The infected leaf also shows brown spots at the end of the petioles. The affected plants may bear a few smaller bolls with immature lint .

8. SYSTEMATIC POSITION: Kingdom :Fungi Division :Ascomycota Class : Deuteromycetes Subclass : Hypocreomycetidae Order : Hypocreales Family : Plectosphaerellaceae Genus : Verticillium Species : V.dahliae (Kleb.1913) V.albo-atrum ( Reinke & Berthhold , 1872)

9. PATHOGEN: Verticillium dahliae , Verticillium alboatrum The fungus produces hyaline, septate mycelium and two types of spores. The conidia are single celled, hyaline, spherical to oval, borne singly on verticillate conidiophores. The micro sclerotia are globose to oblong.

10. MODE OF SURVIVAL : The fungus can survive in the infected plant debris and in soils as micro sclerotia upto 14 years. The seeds also carry the micro sclerotia and conidia in the fuzz . PRIMARY SPREAD: Micro sclerotia or conidia in the soil. SECONDARY SPREAD: Contact of diseased roots to healthy ones . Through dissemination of infected plant parts through irrigation water and other implements .

11. FAVOURABLE CONDITIONS: Low temperature of 15-20 ﹾ C. Low lying and ill-drained soils. Heavy soils with alkaline reaction. Heavy doses of nitrogenous fertilizers .

12. MANAGEMENT: CULTURAL METHODS: Treat the delinted seeds with Carboxin or Carbendazim at 2g/kg. Isolation of affected plants. Follow crop rotation by growing paddy or lucerne or chrysanthemum or barley. Avoid late season irrigation and soil solarisation effectively controls wilt. Growing disease resistant varieties like Sujatha , Suvin and CBS 156 and tolerant variety like MCU 5 WT .

13. CHEMICAL METHODS: Systemic fungicides like Vitavax 0.4% or Organomercurials . Spot drench with 0.05g/l benomyl or carbendazim 500mg/l. Fumigate soil with chemicals such as methyl bromide and chloropicrin.

14. REFERENCES: http:// eagri.org/eagri50/PATH272/lecture13/002.html http://www.padil.gov.au/pests-and-diseases/pest/main/136633 Saha ,L.R., 2002.Hand book of plant diseases,Kalyani publishers,New Delhi.