RUSTS OF SUGARCANE

SYMPTOMS, PATHOGEN, MANAGEMENT

1. STUDENT COURSE TEACHER Ms.THARANI . N Dr. S. PARTHASARATHY ID . No. 2016021048 Asst . Prof . , (Plant Pathology ) COLLEGE OF AGRICULTURAL TECHNOLOGY Affiliated to Tamil Nadu Agricultural University, Coimbatore Kullapuram , Via Vaigai dam, Theni-625 562 RUSTS OF SUGARCANE

2. TYPES There are 3 Rust species (types) that infect Sugarcane : Brown rust - Puccinia melanocephala Orange rust - Puccinia kuehnii Tawny rust - Macruropyxis fulva sp . nov

3. SIGNIFICANCE Sugarcane is one of the plants with the highest bioconversion efficiency This crop is able to efficiently fix solar energy, yielding some 55t of DM /ha annually It’s the world’s largest crop by production quantity (1.9 billion t) Cane accounts for 79% of sugar produced Molasses, Baggase are some other products obtained from this crop

4. Since 1978, sugarcane production in Florida has been threatened by sugarcane rust caused by Puccinia melanocephela . This fungal pathogen is now found almost everywhere sugarcane is grown. The spread of the disease has had considerable economic impact During the 1987, 20% yield loss were noted due to the occurrence of this disease and estimated economic losses $40 million. Screening for resistance has become an integral part of Florida sugarcane breeding programs

5. GLOBAL DISTRIBUTION Brown rust is widespread, infecting cane throughout Africa, Asia, Australia and North and South America for many years. It was first reported in South Africa in 1941. Orange rust was initially confined to Asia and Australia, but was observed in Florida for the first time in 2007 before spreading throughout the Americas. The disease was later reported in western and central Africa in 2010 but has not as yet been observed in southern Africa .

6. In 2008, a third, unknown rust was found on sugarcane, Tawny rust ( Macruropyxis fulva sp . nov .) was observed on N25 in Swaziland and has since spread to most cane-growing areas in South Africa. The disease has also been reported in Mozambique and Zimbabwe.

7. SYMPTOM Early symptoms of all three types of rust are similar and include yellow flecking that can be seen on both leaf surfaces. The flecks gradually elongate to form linear lesions that are also visible on both leaf surfaces. These develop parallel to the leaf veins and darken from the centre. Spores erupt from the lesions after 10-14 days, giving the surface a rough appearance. As the disease progresses, each rust type presents its own unique symptoms, making it possible to distinguish them from each other

8. Brown Rust : Colour - Dark brown to reddish brown pustules Size - upto 20 mm long & 3 mm wide Distribution on leaf - more concentrated near leaf tip Attacks canes of less than 6 months

9. Orange Rust : Colour – orange to orange brown Size - upto 4 mm long and 3 mm wide Distribution on leaf – more concentrated towards the leaf Usually attack canes which crossed 6 months

10. Tawny Rust : Colour - Dark brown to reddish brown may be some purpling around the border Size - upto 20 mm long and 3 mm wide Distribution on leaf - more concentrated near the leaf tip Attack canes at all the ages

11. PATHOGEN Kingdom : Fungi Phylum : Basidiomycota Class : Pucciniomycetes Order : Uredinales Family : Pucciniaceae Genus : Puccinia Species : P. melanocephala H. & P. Syd 1907 P. Kuehnii ( Krueg ) Butler P.erianthi Padw . & Khan.

12. PATHOGEN CHARACTERS Spermogonia and aecia unknown. Uredinia : Primarily hypophyllous (on lower surface of leaves), cinnamon-brown, linear up to 4 mm Urediniospores : Obovoid or ellipsoidal, 25-39 × 17-28 µm, cinnamon to dark-brown, echinulate , germ pores 4-5, equatorial, wall 0.8-2.3 µm; paraphyses hyaline to golden, capitate or spathulate , 32-98 µm × 12-25 µm, wall 1-2.8 µm thick, 4-15 µm at apex.

13. Uredinia of Puccinia melanocephala on Saccharum spp.

14. Urediniospore of Puccinia melanocephala on Saccharum spp. SEM micrograph of P.melanocephala urediniospore illustrating echinulate spines

15. Telia : Hypophyllous , exposed, black to dark-brown Teliospores : 34-56 × 16-24 µm, mostly clavate , walls 2-3.5 µm thick at sides, 2.5-8 µm at apex, upper cell dark brown, lower cell paler, pedicels brown, thin-walled, usually not collapsing, 4-17 µm long; telial paraphyses long, capitate .

16. DISEASE CYCLE Sugarcane rust is an autoecious rust Uredospores are produced from the pustules that break through the epidermis on the underside of the leaves Then the spores disperse from pustules via wind or rain onto the leaves of a new host sugarcane The uredospores then germinate on the sugarcane leaves, develop appresoria , infect new host via penetration on plant’s stomata This cycle can be repeated throughout the year because sugarcane growing areas are conducive for the growth of this pathogen P. melanocephala infection is non-systemic

17. EPIDEMOLOGY MODE OF SPREAD : Rust produces spores that are microscopic, light and hardy making them well adapted to rapid short and long distance dispersal by wind and water splash. Rust is not systemic and therefore does not spread by planting seedcane from an infected field.

18. FAVOURABLE CONDITIONS : Leaf wetness and atmospheric temperature are the environmental factors most influential for rust development Cool (less than 25ºC), misty or light rain, high humidity are conducive for development Studies have shown rust levels to be higher on sugarcane grown on low pH soils than on high pH soils, particularly when high levels of phosphorus and potassium nutrients are present in the soil.

19. MANAGEMENT The best means of control for sugarcane rust is to grow resistant varieties. Eg : N12 has good resistance to brown rust . Other rust resistant varieties are co-421, co-467, co-575, co-603, co-678, co-732, co-826, co-928 Follow the long furrow or pair row method of planting. Removal of affected and dried leaves and destruction by burning. After the harvest of diseased crop the leftover trash should be burnt immediately .

20. Foliar application of Mancozeb ( 0.15%) with callixin (0.075%) 2 to 3 times at an interval of 10 to 12 days may be done immediately after the disease appear. Applying following fungicides to actively growing crops before or at the first sign of rust can reduce the disease development . TRADE NAME PRODUCER TARGET RATE APPLICATIONS Abacus BASF Brown Rust Tawny Rust 1.6 L/ha in 200 L water 2 Amistar Xtra Syngeta Brown rust Orange rust 500 ML/ha in 400 L water 2

21. REFERENCES P.C.DAS, 2018, Plant Diseases, Kalyani Publishers, New Delhi I.R.SAHA, 2010, Hand Book of Plant Diseases, Kalyani Publishers, New Delhi