Black stem rust of wheat

symptoms,pathogen and management

1. STUDENT COURSE TEACHER CHANDRA LEKHA. R Dr. S. PARTHASARATHY ID. No. 2016021006 Asst . Prof. , (Plant Pathology ) COLLEGE OF AGRICULTURAL TECHNOLOGY Affiliated to Tamil Nadu Agricultural University, Coimbatore Kullapuram , Via Vaigai dam, Theni-625 562 BLACK (STEM) RUST OF WHEAT

2. SIGNIFICANCE W heat is the sixth most important crop. Grown yearly on 220.4 million hectares. Possess net worth more than 22 billion dollars. World trade in wheat is greater than for all other crops combined. Losses upto 60 to 70%.

3. SIGNIFICANCE M ajor disease of wheat and, therefore a potential threat to the world food supply. More than 5 billion dollars are lost due to cereal rust each year. Wheat black stem rust was a serious problem in ancient G reece and Rome. Robigalia festival – sacrificed red animals such as dogs, foxes and cows to the rust god R obigo .

4. MILESTONES 1767 - Italian scientist Fontana and Tozzetti independently provided first detailed descriptions of stem rust fungus in wheat . 1797 - Persoon named it P uccinia graminis . 1854 - the Tulasne brothers recognized that some rust fungi could produce as many as five spore stages. 1865 - Anton deBary first demonstrated the heteroecious lifecycle of a rust fungus with Puccinia graminis .

5. GLOBAL DISTRIBUTION The disease is present almost everywhere wherever wheat crop is grown. Epidemics of stem rust of wheat often occur in different parts of the world. More prevalent in North A merica, Ethiopia, India, China and Australia.

6. GLOBAL ASSESSMENT SURVEY © slideshare.net

7. WHEAT STEM RUST INFECTION TYPES ©agric.wa.gov.au

8. SYMPTOMS Do not produce symptoms until 7-15 days from infection. the oval pustules ( uredinia ) of powdery, brick-red urediniospores break through the epidermis. Microscopically, these red spores are covered with fine spines. The pustules may be abundant and produced on both leaf surfaces and stems of grass hosts.

9. SYMPTOMS Later in the season, pustules ( telia ) of black teliospores begin to appear in infected grass species. Microscopically, teliospores are two celled and thick walled. The stem become dry and cracked. The plant produces less or no grains.

10. WHEAT STEM RUST ©ars.usda.gov

11. U redinospores Teliospores ©apsnet.org

12. Initial and later stage of infection © apsnet.org

13. Pycnia appear on barberry plants in the spring, usually in the upper leaf surfaces. They are often in small clusters and exude pycniospores in a sticky honeydew. Five to 10 days later, cup-shaped structures filled with orange-yellow, powdery aeciospores break through the lower leaf surface. The aecial cups are yellow and sometimes elongate to extend up to 5 mm from the leaf surface . Microscopically, aeciospores have a slightly warty surface.

14. ©apsnet.org Barberry plant Pycniospores Aeciospores

15. SYSTEMATIC CLASSIFICATION Domain : Eukarya Kingdom : Fungi Phylum : Basidiomycota Subphylum : Pucciniomycotina Class : Pucciniomycetes Order : Pucciniales Family : Pucciniaceae Genus : Puccinia Species : P. graminis f. sp. tritici

16. PATHOGEN CHARACTERS The pathogen is an obligate parasite. It cannot exists as saprophyte. In most rust fungi, only the teliospores are adapted to survive apart from a living host plant for more than few months under field conditions. Puccinia graminis is heteroecious and polycyclic.

17. STAGES OF THE PATHOGEN Puccinia graminis is macrocyclic, producing all five spore stages Stage 0 : Spermagonium Stage 1 : A ecium Stage 2 : U redium Stage 3 : T elium Stage 4 : B asidium

18. HOSTS Wheat and barley. Common barberry (and some additional B erberis , Mahoberberis and Mahonia spp.)

19. DISEASE CYCLE ©apsnet.org

20. EPIDEMIOLOGY Stem rust is favoured by hot days (25-30ºC/ 77-86ºF), mild nights (15-20ºC/ 59-68ºF), and wet leaves from rain or dew . It appears in the month of March in Northern India. In Southern and Peninsular India it appears very early in the 4th week of November. Both aeciospores and urediniospores require free water for germination as do the other spore stages. Infections occur through stomata.

21. SURVIVAL OF PATHOGEN Stem rust can survive as teliospores during winter when aeciospores are a major source of inoculum . It generally survives as mycelium or uredinia on volunteer wheat during the non-wheat growing season. Sporulating uredinia are active in tropical and some subtropical areas throughout the winter . Occasional dormant mycelium may survive beneath the snow pack in more northern temperate regions .

22. Primary and secondary inoculum of wheat stem rust ©ohioline.osu.edu

23. MODE OF SPREAD Primary spread - Urediniospores and aeciospores are wind borne. Secondary spread - Rain is necessary for effective deposition of uredinospore involved in regional spore transport. Teliospores remain with the straw.

24. MANAGEMENT Adjustment of sowing dates. Growing short and long duration crops. Applications of balanced fertilizers to the crop. Eradication of barberry trees around the wheat field.

25. MANAGEMENT Cultivation of Rust Resistant Varieties: The cultivation of varieties immune to the rust disease is an important means of combating the disease. Some rust resistant varieties of wheat are available in India. NP 710, NP 718 and NP 770 find favour with the farmers.

26. MANAGEMENT The newly bred hybrids NP 822, NP 823 and NP 825 have given good results. They possess high degree of rust resistance. In addition they are high yielders . Lerma Rojo , S afed Lerma, C hoti L erma and Sonalika are highly resistant to all three rusts in the field.

27. MANAGEMENT Use of Fungicides Including Antibiotics: Practically no variety is resistant for a long period due to emergence of new physiological races. Grewal and Dharam Vir (1959), Mathur et al (1961) and Tandon et al (1968) recommended Zineb and Maneb to control wheat rusts effectively.

28. MANAGEMENT Srivastava, Rai and Aggarwal (1972) recommended the use of Dithane Z-78 and Dithane M-45. The latter controls the disease even at lower conc. (1.5 lbs/acre) when applied with sticker. The yield increased by 33.3% over the control. A number of other chemicals like RH-124 and Plantavax have as well given quite encouraging results. Heagle and Key (1973) reported that Ozone (O 3 ) inhibits infection, hyphal growth and uredospore formation of wheat stem rust fungus.

29. MANAGEMENT Application of paratoluene sulphonylamide to the soil at the rate of one gram per square meter is effective. Actidione has been recommended to be a useful antibiotic as a fungicide for the control of rusts plus zinc sulphate at fifteen days interval from the first week of February are quite effective.

30. REFERENCES Gupta, V.K., Paul, Y.S., and Sharma Sathish , K. 2012. Fungi and Plant D iseases. Kalyani publishers, New Delhi. https://www.biologydiscussion.com/plants/plant-diseases/stem-rust-of-wheat-with-diagram/64306 https://www.apsnet.org/edcenter/intropp/lessons/fungi/Basidiomycetes/Pages/StemRust.aspx