Rust diseases of wheat

INTRODUCTION
OCCURENCE AND IMPORTANCE
DIFFERENT TYPES OF WHEAT RUST
BLACK RUST
BROWN RUST
YELLOW RUST
COMPARISION OF ALL THREE RUST
SYMPTOMS
SIGNIFICANCE
HISTORY
RUST CYCLE
STAGES OF PATHOGEN
EPIDEMIOLOGY
RUST CYCLE IN INDIA
UG99

1. RUST DISEASES OF WHEAT

2. INTRODUCTION Second most important cereal after rice. Bread wheat contributes approximately 95% to total production Remaining 4% from durum wheat and 1% from Dicoccum World(2017) Production: 771.7 million tons Area: 217 million ha. Average productivity: 3067kg/ha India(2017) Production: 98.5 million tons Area:30.72 million ha Average productivity: 3000 kg/ha. India ranks 3 rd in production after European Union and China.

3. Occurrence and importance Rusts are among the most important fungal diseases of wheat worldwide. This is due to their wide distribution, capacity to form new races that can attack previously resistant cultivars, ability to move long distances and potential to develop rapidly under optimal environmental conditions. Stripe, Stem and Leaf rust comprise the three rust diseases of wheat.

4. Wheat Rusts in India Stripe Rust- More prevalent on north western parts and northern hills. Leaf Rust– All parts of the country Stem Rust– Central & Peninsular parts

5. STEM RUST

6. SIGNIFICANCE Major 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 Greece and Rome. Robigalia festival – sacrificed red animals such as dogs, foxes and cows to the rust god Robigo . Annual Losses upto 60 to 70%.

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

8. History( milestones) 1767 - Italian scientist Fontana and Tozzetti independently provided first detailed descriptions of stem rust fungus in wheat . 1797 - Persoon named it Puccinia 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 Stakman et al., 1918 demonstrated that stable variants , originally termed physiological races , and later known as races , strains , biotypes or pathotypes , occurred within Puccinia graminis f . sp . tritici Craigie , 1927 role of pycnia in sexual reproduction of rust fungi

9. 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 America, Ethiopia, India, China and Australia.

10. SYMPTOMS Do not produce symptoms until 7-15 days from infection. 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.

11. 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.

12. WHEAT STEM RUST INFECTION Initial stages Later stages

13. WHEAT STEM RUST

14. urediospore s teliospores

15. 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

16. Barberry plant Pycniospores Aeciospores

17. STAGES OF THE PATHOGEN • Puccinia graminis is macrocyclic heteriocious , producing all five spore stages Stage 0 : Pycnial Stage 1 : Aecial Stage 2 : Uredial Stage 3 : Telial Stage 4 : Basidial

18. HOST MAIN HOSTS: Wheat and barley. ALTERNATE HOSTS: Berberis vulgaris

19. EPIDEMIOLOGY Stem rust is favoured by hot days (25-30°C), mild nights (15-20°C), 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.

20.   Environmental conditions required (TEMPERATURE° CELCIUS) Stem rust Minimum optimum maximum light Free water Germination 2 15-24 30 low essential Germling 20 low essential Appressorium 16-27 None essential Penetration 15 29 35 high essential Growth 5 30 40 high None Sporulation 15 30 40 high None

21. Disease cycle of stem rust

22. Disease cycle in absence of alternate host

23. Rust cycle in India In 1933, late professor K. C. Mehta worked on the problem of annual recurrence of rust in India and solved the mystery. He proved that the uredospore’s produced on the hills are responsible for the annual recurrence of rust disease in the plains of India . According to him: (a) Uredospore’s can survive in the summer in hills (at higher altitude of 1300-2500 metres ). (b) They survive on self sown wheat plants and tillers. The atmospheric conditions on high altitude and the low temperature help for the survival of uredospore’s . (c) In the hills the wheat crop is sown in September and October, its gets infected very soon whereas in the plains of India the wheat crop is sown in the months of October and November. At that time the hilly crop is already heavily infected by rust disease. The wheat plants are infected by the uredospore’s survived during the summer season in hills .

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

25. SURVIVAL 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.

26. MANAGEMENT • Early sowing. • Growing short and long duration crops. • Applications of balanced fertilizers to the crop. • Eradication of barberry trees around the wheat fields as well as volunteer plants. *Cultivation of Rust Resistant Varieties:Np 710, Np 718 and Np 770,  Np 822, Np 823 and Np 825 etc. Practically no variety is resistant for a long period due to emergence of new physiological races. Use of Fungicides: propiconazole25EC @ 0.1%

27. Yellow rust of wheat

28. Systematic position Kingdom: Fungi Phylum: Basidiomycota Class: Urediniomycetes Subclass: Incertaesedis Order: Uredinales Family: Pucciniastraceae Genus: Puccinia Species: P. striiformis var. tritici

29. History Gadd first described stripe rust of wheat in 1777. In 1896,Eriksson and Henning showed that stripe rust resulted from a separate pathogen, which they named P. glumarum . In 1953, Hylander et al. revived the name P. striiformis .

30. Symptoms The first sign of stripe rust is the appearance of yellow streaks (pre-pustules), followed by small, bright yellow, elongated uredial pustules arranged in conspicuous rows on the leaves, leaf sheaths, glumes and awns . Mature pustules will break open and release yellow-orange masses of uredospores . In some varieties, long, narrow yellow stripes will develop on leaves. The infected tissues may become brown and dry as the plant matures or becomes stressed. Severe early infection can result in plant stunting.

31. Symptoms On plant teliospores

32. Distribution In India, Hills, foothills and plains of north western India In World, Europe and Australia(commonly known as yellow rust).

33. EPIDEMIOLOGY Puccinia striiformis f. sp. tritici can survive as dormant mycelium on wheat. Stripe rust is most common in higher elevations and cooler climates. The pathogen is best sustained when night time temperatures are <60°F (15°C). Stripe rust can develop on wheat at lower temperatures than other rusts. Optimum uredospore germination occurs at 44-59°F (7-15°C). Infection and disease development is most rapid between 50-60°F (10-16°C). Heavy dew or intermittent rains can accelerate the spread of the disease. Infection tends to cease when temperatures consistently exceed 71-73°F (21-23°C).

34. Pathogen survives in the cool temperatures of hills ( Himalayas)and the primary infection takes places by middle of January in the foot hills and sub mountainous parts of north western India.Uredospores are spread via wind currents to healthy plants where they can initiate new infections. Maximum and minimum temperature range of 19-21 and 6-10°C and maximum and minimum relative humidity of 87 and 46 per cent were favourable for disease development, respectively. Rainfall played an important role in steep increase in yellow rust severity

35.   Environmental conditions required (TEMPERATURE° CELCIUS) STRIPE RUST Minimum optimum maximum light Free water Germination 9-13 23 low essential Germling 10-15 low essential Appressorium Not formed Penetration 2 8-13 23 low essential Growth 3 12-15 20 high None Sporulation 5 12-15 20 high None

36. MANAGEMENT Cultural practices and chemical control is same as that of stem rust. Resistant varieties: HS562, HS542, HS507, PBW 343 UNNAT, PBW725, PBW697 VL 907, VL892, HP349 etc.

37. Brown rust

38. Systematic position Kingdom: Fungi Phylum: Basidiomycota Class: Urediniomycetes Subclass: Incertaesedis Order: Uredinales Family: Pucciniastraceae Genus: Puccinia Species: P. recondita

39. SYMPTOMS:   Generally found on leaves but may also infect glumes and awns. Symptoms begin as small circular to oval yellow spots on infected tissue of the upper leaf surface. As the disease progresses, the spots develop into orange-colored pustules that may be surrounded by a yellow halo The pustules produce a large number of spores that are easily dislodged from the pustule, resulting in an “orange dust” on the leaf surface or on clothes, hands, and equipment. As the disease progresses, black spores may be produced, resulting in a mixture of orange and black lesions on the same leaf. Tiny orange lesions may be present on seed heads, but these lesions do not develop into erumpent pustules.

40. Symptoms On plant teliospores

41. significance Distributed everywhere in areas where wheat is grown. Most common in occurrence as compared to other rusts. Causes about 20% yield losses. It is macrocyclic heterocieous rust and require alternate host: Thalictrum Anchusa Isopyrum , Clematis to complete life cycle.

42. epidemiology Long-distance spread of urediniospores is influenced by wind patterns and the orientation of the spore to latitude. The fungus can infect in less than three hours in the presence of moisture and temperatures below 20 °C; however, more infections occur with longer exposure to moisture.   Germination process requires moisture and temperatures between 15–20 °C. After around 10–14 days of infection, the fungi will begin to sporulate and the symptoms will become visible on the wheat leaves.

43.   Environmental conditions required (TEMPERATURE° CELCIUS) Leaf rust Minimum optimum maximum light Free water Germination 2 20 30 low essential Germling 5 15-20 30 low essential Appressorium 15-20 None essential Penetration 10 20 30 No effect essential Growth 2 25 35 high None Sporulation 10 25 35 high None 2 20 30 low essential

44. lifecycle Produces five types of spores: basidiospores , pycniospores , aeciospores, urediospores and teliospores . First two spores on alternate host and aeciospores infect wheat leads to production of urediospores which are repeating spores to teliospores which are repeating spores. From teliospores on meiosis a nucleus is formed which yield 4 basidiospores which infect alternate host.

45. LIFECYCLE

46. Disease cycle

47. MANAGEMENT Early-maturing cultivars. Destruction of volunteer plants RESISTANT CULTIVARS: Rohini (CPAN1676), Tobarri66, RL6058 CHEMICL CONTROL with   triazole  fungicides

48. PHYSIOLOGICAL SPECIALISATION A population of individuals the members of which are similar to other such populations on morphological grounds but differ on physiological or pathological grounds. In pathogenic fungi, races are identified on the basis of infections on different species of the host. Biotypes are identified on the basis of infections on different varieties of the host

49. Ug99 Not a single entity “Ug99 Race group” have 11known members Group of Pgt races sharing almost identical molecular fingerprints to the original Ug99 isolate the group of Pgt races sharing almost identical molecular fingerprints to the original Ug99 isolate (race TTKSK). Most races in the group have virulence to Sr31, but Sr31-avirulent progenitors/relatives are also included 1999: race TTKSK “Ug99” identified 2014: 11 members of the Ug99 race group Spread throughout Africa and into Asia.

50. Ug99 race group is now in 11 countries 8 identified races now 11

51. REFERENCES Gupta, V.K., Paul, Y.S., and Sharma Sathish , K. 2012. Fungi and Plant Diseases. Kalyani publishers, New Delhi. https://www.biologydiscussion.com/plants/plant-diseases/stemrust-of-wheat-with-diagram/64306