SYMPTOMS AND LIFE CYCLE OF Alternaria solani

Alternaria solani is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato. Despite the name "early," foliar symptoms usually occur on older leaves. If uncontrolled, early blight can cause significant yield reductions.Primary methods of controlling this disease include preventing long periods of wetness on leaf surfaces and applying fungicides.

Geographically, A. solani is problematic in tomato production areas east of the Rocky Mountains and is generally not an issue in the less humid Pacific or inter-mountain regions. A. solani is also present in most potato production regions every year but has a significant effect on yield only when frequent wetting of foliage favors symptom development.

1. PAT 201-FUNDAMENTALS OF PLANT PATHOLOGY(2+1)

2. PGP COLLEGE OF AGRICULTURAL SCIENCE ( Affiliated to TamilNadu agricultural university,Coimbatore-3 ) S enthamangalam R d, P alani N agar, Namakkal -637405 SYMPTOMS AND LIFE CYCLE OF Alternaria solani STUDENT COURSE TEACHER Ms.Malathi.P Mr.M.Krishnamoorthi ID.No.2019024051 Assistant professor PGP college of agricultural sciences Course A ssociate Ms.T.Suganya

3. INTRODUCTION Alternaria solani Causative agents - early blight in solanum species The pathogen produces distinctive “ bullseye ” patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato.

4. Alternaria It is multicellular pigmented spores are produced in chains or in branching fashion

5. Alternaria solani

6. Alternaria poori

7. Alternaria brassicicola

8. Early blight ( Alternaria solani ) on Tomato ( Lycopersicon esculentum )

9. SYMPTOMS Foliar symptoms of Alternaria solani - oldest leaves and smart as small lesions that are brown to black on color . These leaf spots - concentric rings Both the area around the leaf spot and the entire leaf may become yellow or chlorotic .

10. Under favorable conditions (e.g., warm weather with short or abundant dews) - significant defoliation of lower leaves , leading to sunscald of the fruit. Stem lesions - dark, slightly sunken and concentric in shape. Fruits spots are similar leaves – brown with dark concentric circes . Mature lesions - a black, velvety mass of fungal spores

11. SYSTEMATIC CLASSIFICATION / TAXONOMIC POSITION Domain : Eukarya Kingdom : Fungi Phylum : Ascomycota Class : Dothediomycetes Order : Pleosporales Family : Pleosporaceae Genus : Alternaria Species : solani

12. PATHOGENIC CHARACTER The mycelium - septate and branched, hyaline in the beginning and later becomes darker in color The conidia - 12-20 × 120-296 µm Conidia - 9-11 transverse septa (cross walls). Conidiophores are short and produces an obclavate of muriform shaped conidia with horizontal and vertical septation and it is pointed at distal end.

13. MYCELLIUM

14. MODE OF REPRODUCTION Alternarias - no sexual or perfect stage. The multiply asexually - sporulation. asexual spores - exogenously are the conidia. The conidia are produced at the tips of ordinary hyphae which are comparatively short and dark coloured .

15. The conidia - large, dark coloured, several celled and beaked. The number of cells - 8-14 or even more . The component cells occur packed in muniform , conidal masses. The septa dividing the spore into cell and both transverse and vertical and their number is not fixed.

16. DISEASE CYCLE

17. The fungus can survive in soil and in infested crop and weed residues. It may be seed-borne and carried by wind, water, insects, workers and farm equipment . The spores that land on tomato plants will germinate and infect the leaves when they are wet.

18. Spores enter - leaf, steam or fruit . The fungus more active - mild to warm temperature and wet weather. The disease worse during - rainy seasons. Early blight is most severe on plants stressed by a heavy fruit load, nematode attack, or low nitrogen fertility.

19. FAVOURABLE WEATHER CONDITIONS Maximum temperature of 15-29°C Minimum temperature of 4-12°C Average relative humidity >60% RH I (Morning)>76% RH II (Afternoon)>25%

20. MANAGEMENT ASPECTS CULTURAL CONTROL Clear infected debris from field to reduce inoculum from the next year. R otate to a non- solanaceous crop for atleast three years. Removal and destruction of infected plant debris should be done because the spores lying in the soil are the primary source of infection.

21. CHEMICAL CONTROL Very early spraying with zineb or captan 0.2% and repeating it for every 15-20 days gives effective control.

22. CONCLUSION Moreover to determine the levels of genetic varation of alternaria spp . Is important to know the population structure and migration structure of the pathogen.

23. Early blight of tomato,dark black and slightly sunken, sunscald of fruit. Picture courtesy : J.B.Jones , T.A.Zitter , M.T.Momol , and S.A.Miller , Tomato diseases.

24. Conidia of alternaria solani , blue brightfield conidia, fungus infection. Picture courtesy : nature picture library conidia