• Currently there are about 50 varieties of sugarcane under intensive cultivation in India.
• Over 100 fungi, 10 bacteria, 10 viruses and about 50 species of nematodes are pests of sugarcane in different parts of the world.
• Wherever the crop is grown intensively virulent forms of certain pathogens are chronic.
• When a given pathogen becomes severe enough to get the upper hand, the farmers replace the susceptible variety with resistant or tolerant varieties.
• Thus, in many parts of the world, including India, there are continuous, forced replacements of sugarcane varieties.
• There are over 30 diseases of sugarcane in India, some are of major importance because they are widespread and cause severe losses in yield.

Causal Organism : Colletotrichum falcatum Went

Class : Deuteromycetes

Order : Melanconiales

Family : Melanconiaceae

• Red rot is one of the major diseases of sugarcane found in many areas of the world. In India it has caused extensive damage in recent past and remains endemic in severe form in some parts.
• During 1939-1942 it caused heavy losses in Bihar and Uttar Pradesh.
• The disease has been studied in detail during the past half century, as evidenced by the voluminous literature on it.
• Butler and his associates in India investigated the disease in great detail during 1914-1918. This led to the work on breeding for disease resistant varieties to control the disease.
• A lead in this activity was by The Sugarcane Breeding Institute, Coimbatore, South India.

• The discolouration and withering continues from the tip to the leaf base until the whole crown withers and the plant dies, within 4 to 8 days.
• In a single stool, most of the stalks may wither almost simultaneously.

• The tissues are reddened throughout the basal portion, especially the vascular bundles, which are intensely red; there may be cross-wise white patches interrupting the reddened tissues.

• Since reddening is a common symptom of other diseases of sugarcane, the white patch symptom is an important diagnostic characteristic of red rot.
• When a diseased plant is open, a characteristic becomes evident.

Class : Ascomycetes

Order : Sphaeriales

Family : Mycosphaerellaceae

• The fungal mycelium is present inter-cellularly, mainly in the parenchymatous cells of the path.
• The hyphae are thin, hyaline, septate, profusely branching and contain oil droplets.
• The acervuli, which are characteristic of the genus, are formed on the surface of the rind, in the leaf mid-rib and sometimes in the pith region. They are minute, black and velvety.
• The compact hymenial layer produces the long, rigid, bristle-like setae, which are septate, dark brown at the base and lighter towards the tip.
• Inter-spaced between the setae are numerous club-shaped to linear, hyaline, single-celled conidiophores, measuring approximately 20 X 8 m.
• The conidia, which are borne singly oil the conidiophores, are single celled, thin walled, hyaline, falcate, granular and guttulate, measuring 16-48 x 4-8m In artificial cultures terminal and intercalary, thick-walled, greenish-black chlamydospores are often produced.
• The conidia germinate readily to produce single germ tubes at the tips of which an elliptical, ovoid or irregular, appresoria are formed.
• The perfect stage of the fungus has been observed both in nature and in culture by several authors.

• The planting material, viz., the setts, may harbour the fungus and thus perptuate the disease from season to season.
• The fungus may also persist in the soil oil diseased clumps and dry leaves left in the field after harvest.
• The primary infection, however, appears to be mainly from infected setts.
• Secondary spread in the field may be through irrigation water, cultivation tools anti implements and wind-borne inoculum.
• If the conidia settle on the leaves they may germinate and invade the leaves through various types of wounds including the splitting of the mid-rib so common in many varieties.
• Stem infection may take place through insect bores and root primordia.
• The soil-borne fungus may also enter the healthy setts through cut-ends, and cause early infection of the shoots.
• The prevalence of several pathogenic strains of the fungus has been reported from many countries, including India.
• In general, light-coloured physiologic races sporulate readily and are more pathogenic than the dark-coloured strains that sporulate sparingly.
• Though the perfect stage of the fungus has been observed in nature, the role of ascospores in the disease cycle is not understood.

• Red rot management in sugarcane has become an important issue in all sugarcane areas. While early stage detection may not be quite easy, during later stages, the cane breaks down.
• The canes are to be split open lengthwise to see dull red tissue, interrupted by white patches across the stalk. These patches are characteristic of red rot of sugarcane. Monsoon period enables faster disease spread and drying of the crop.
• The best remedy for avoiding this fungal disease is to cultivate only resistant sugarcane varieties that have been released for cultivation in different sugarcane growing states. Phytosanitation, being the key to manage this disease, stringent domestic quarantine measures to prevent movement of cane setts from endemic areas to new areas has to be enforced by all concerned agencies including sugar mills.
• In recent times, the disease has spread into many states.
• Following good cultural practices such as clearing fields of excessive trash and ensuring efficient drainage.
• Healthy setts only are to be planted to avoid poor plant stand due to rotting.
• Affected fields should be isolated through bunding to prevent movement of water to adjacent fields.
• Rattooning of infected fields should be strictly avoided.
• Crop rotation in the affected fields could reduce disease inoculum.
• Hot water treatment of setts before planting at 52 degree C for 30 minutes is also recommended.
• Planting fungicide treated seed setts is to be followed as a general practice to prevent introduction of the pathogen into sugarcane fields.
• Chemical control: Sett treatment with 0.25% Thiophanate methyl, a systemic fungicide will protect the setts against the primary infection of red rot for 90 days.
• In addition to the various sanitary precautions mentioned above, red rot may also be controlled by growing resistant or tolerant varieties. Inter-generic and inter-specific crosses with Saccharum spp., in the latter case using S.spopntaneum and S. robustum with S. officinarum have yielded many economically important cane varieties, some of which are highly resistant, or at least tolerant, to red rot.
• Cultivation of resistant varieties: By far the most effective measure for management of red rot is use of resistant varieties for cultivation. Varieties viz. Co 8021, Co 85019, Co 86010 and Co 86032, Co86249 and Co 93009, Co 99004 and Co 99006 are tolerant/resistant to red rot in Tropical India. The varieties Bo 91, Co89003, Co 98015, Co 99015, Co 99016, Co S 96275, Co S 99259, Co Pant 90223 and Co Pant 94211 are resistant in SubTropical India.

Causal Organism : Xanthomonas rubrilineans

Class : Schizomycetes

Order : Pseudomonadales

Family : Pseudomonadaceae

• This is another bacterial disease of sugarcane which has a world-wide distribution.
• It has been known since 1893 in Java and since 1903 in Australia, but in India only since 1933, when it was reported by Desai, and also McRae.
• In 1960 Rangaswami made detailed studies on the disease and its causal agent.

• Red stripe is characterized by the appearance on the leaves of chlorotic lesions carrying dark red stripes 0.5-1.0 mm in breadth and several mm in length, either distributed all over the blade, or concentrated in the middle
• Several of them may coalesce to cover large areas of the leaf blade, and to cause wilting and drying of the leaves.
• Whitish flakes occur on the lower surface of the leaf, corresponding to the red lesions on the upper surface.
• These flakes are the dry bacterial ooze. When young shoots are affected, shoot or top rot may result.
• The growing points of the shoot are yellow and later reddish with dark brown stripes on the shoots.
• The rotting may commence from the tip and spread downwards.
• If the affected plants are cut by splitting the shoot downwards, dark red dis-colouration of the tissues may be seen.
• In the affected canes cavities may form in the pith region, and the vascular bundles are distinct because of the dark red dis-colouration.
• The diseased and rotting shoots can be easily pulled out and separated from the plant.

• The disease spreads in the field by wind and rain, and by cutting, as the basal stem from which the setts are taken is mostly free from the bacterial infection.
• The bacterial ooze form the infected leaves and shoots dries up to form a thin crust on the surface.
• When dry, the bacterial cells spread freely by wind.
• The cells falling on the host plants, enter them through natural openings or wounds and establish themselves in the various tissues, including the xylem.
• Infected parenchymatous cells may collapse and normal functioning of the plant parts may fail.
• Several grasses, including ragi and bajra, have been reported to be infected by the bacteria.
• These hosts may also play a role in the perpetuation and spread of the pathogen.

• This is a difficult disease of sugarcane to control.
• When-ever the disease is noticed, the affected plants should be removed and burnt.
• Such systematic destruction of the affected plants reduces the disease incidence.
• Growing resistant varieties is, however,the best method of control.

• This disease of sugarcane is common in India and in most of the sugarcane areas of the world including Hawaii, mainland United States, Mexico, West Indies, parts of Africa, and South America.
• In India it is found in all the sugarcane tracts.

• A characteristic pineapple smell is associated with the rotting and hence the name.
• The fungus produces both microconidia and macroconida.
• The microconidia are hyaline when young but become almost black at maturity.
• They are thin walled aµm the chains of microconidia are produced endogenousnd cylindrilorm, measuring 10-15 µm x 3.5-5.0µm in the conidiophores and are pushed out in succession.
• The conidiophores are linear, thin-walled, about 100µm in length and are formed terminally on short basal cells.
• The macroconida are produced in chains of up to 20µm short, lateral conidiophores, which measure 20-80 x 4 µm. They are spherical, elliptical, truncale or sometimes pyriform and are hyaline to olive-green or black, measuring 16-19 x 10-12 µm.
• The fungus produces the ascigerous of perfect stage in culture media and at times on the host tissues.
• The perithecia are gregarious and flask shaped, with a long narrow beak.
• The basal portion measures 200-350 µm in diameter and the beak up to about 1200µm in length and 30-40µm in diameter.
• The asci are clavate, and the ascospores are convex to elliptical and measure 7-10 x 2.5-4 µm.

• The fungus is soil-borne, entering the setts through the cut ends.
• Inside the sett it spreads rapidly through the parenchymatoous tissues and causes sett rot.
• The buds on the setts may also be affected and secondary organisms may hasten the decay.
• Occasionally the infected setts may also be responsible for the spread of the pathogen.
• The micro and macroconidia may live saprophytically in soil for several years and infect the setts when planted.
• Insects also play a part in the dissemination of the pathogen.
• The specific role of the ascigerous stage in perpetuating the fungus is not under stood.
• The same fungus also infects banana, papaya, cocoa, coffee, mango, pineapple, arecanut, coconut, palmhyra, date palm and several other hosts.

• Pretreating the setts with hot water has been found to stimulate germination of buds and hasten growth so as to help the young plants to overcome the competition with the pathogen.
• A certain amount of resistance to the disease has been found in a few sugarcane varieties in other countries, but field sanitation practices combined with chemical pre-treatment of the setts are quite effective in controlling the disease.

• This is one of the early known diseases of sugarcane in India.
• It was first reported by Butler and Khan in 1913, from North India.
• It has been reported to cause severe damage to sugarcane crops in many parts of India. During 1965-1967 it caused severe damage to sugarcane crop in the Deccan plateau
• Same disease has been reported from Mexico, Argentina, Barbados, Columbia, Trinidad, Uganda, South Africa and United States of America.

• On examination of affected clumps , the pith will be seen discoloured purple or dirty reef, with longitudinal streaks
• The leaves of affected clumps gradually turn yellow and dry up.
• A characteristic disagreeable odour is also associated with such diseased canes.
• A cottony white mycelium can also be seen in the pith region.
• Frequently this fungal disease is associated with a saprophytic bacterial growth and often the bacteria are mistaken as causal agents.

• The fungal mycelium is abundant in the infected canes.
• The hyphae are hyaline, thin walled and septate.
• They produce numerous microconidia on simple or branched, lateral or terminal hyphae, but NO macroconidia are produced.
• This is an important character which is distint from that of Fusarium. The conidia are oval to elliptical, and measure 4-12 x 2-3µm in size. They are mostly unicellular, but the ones formed later in the advanced growth of the fungus may be septate
• Conidia readily germinate to produce single germ tubes.
• The fungus is transmitted from place to place through the infected seed setts.
• When the diseased setts are planted, the eyes may fail to develop or often the shoots arising from the eyes may wilt, due to the infection spreading to the shoots.
• Root formation in such setts may be very poor. The fungus can also survive in soil as a saprophyte for 2-3 years.
• Near-neutral and alkaline soils are favoured by the fungus. The perfect stage is not known.

1.  The disease is controlled by selecting seed setts from disease free areas.
2.  Alkaline soils may be avoided for growing the crop. The setts, selected from disease free stalk, should be      dipped in organomercurial fungicide before planting.
3.  Dipping the setts in 40 ppm of boron or manganese, or spraying the plants with either of these minor      elements reduces the disease intensity.
4.  The varieties Co-617 and B.P.-17 are more resistant than others; hence they should be used when      growing crop in the wilt-sick soils.

• This disease was first observed in Maharashtra on sugarcane variety Co. 419 in 1942.
• At present it is reported to be widespread in parts of Andhra Pradesh, Telangana, Mysore, Bihar, U.P. and Tamil Nadu.
• The disease is more severe on the ratoon crops than on the first planted ones.

• The virus is readily transmitted by sap inoculation and in the field it is transmitted through infected setts and perpetuated through crop ratooning. The aphids are the vectors for this disease.
• The same virus also infects jowar, Napier grass and Madras grass.

• The disease is controlled by eradication of diseased parts as soon as symptoms are noticed
• Avoid selection of setts from diseased area
• pre-treating the healthy setts with hot water at 52°C for 1 hour before planting
• Treating them with hot air at 54°C for 8 hours and spraying twice a month with aphidicides.

• This is one of the oldest and most common diseases of sugarcane known in many counties.
• The disease was first reported from Brazil in 1869, since when it has been reported from Puerto Rico, West Indies, Columbia and Australia.
• In India Rangaswami reported its occurrence in Tamil Nadu State in 1960, and it is now known in other sugarcane areas of South India.

• The disease is characterized by three distinct symptoms.
• On the leaves characteristic longitudinal streaks or stripes, 1/8 to ¼ inch in width and several inches in length are found, these stripes are pale yellow in colour, later turning brown.
• The affected canes are stunted with short internodes, giving the plant a bushy appearance. When such canes are split open or cut transversely, a dull yellow bacterial ooze comes from the cut ends.
• In advanced cases, cavities may develop in the pith region.
• The fibro-vascular bundles are deep red and this is more intense at the nodal regions of the stem.
• The causal bacterium is variously named by different authors, but the above name is universally accepted at present.
• The bacterium is a hort rod, 1.0-11.5µm x 0.4-0.5µm, motile by means of a single polar flagellum.
• Gram negative, non-spore forming, non-capsular and non-acid fast.
• On beer extract agar it produces a yellow spreading and slimy growth.

• The disease is primarily spread through the setts taken from diseased plants.
• The secondary spread may be through agricultural implements, including the cutting knife.
• In the field the infection may spread by wind and water, the source of pathogen being the gummy bacterial ooze coming out of diseased tissues.
• Certain insects, particularly flies, play a significant role in transmitting the pathogen from place to place.
• The bacterium can survive in the insect's body for a long time and in this way may be transmitted long distances.
• On entry into the host the bacterium reaches the vascular tissues and becomes systemic.
• Besides sugarcane, several plant species falling under Graminae, including maize, sorghum, Panicum spp. and some other grasses have been found to be infected by this bacterium.
• These hosts may help in many ways the bacterial spread and perpetuation.

• As in other diseases of sugarcane, gummosis can be controlled by selecting setts from disease-free plants, and adopting strict field sanitation practices.
• In the Fiji Island the disease was completely eradicated by destroying the diseased canes and growing resistant varieties.
• Studies on the availability of resistant stock among the sugarcane varieties in India are needed.

• Pokkah Boeg caused by Gibberella fujikuroi (Saw.) Wollenw. Wineland with its imperfect stage Fusarium moniliforme Sheldon.
• Downy mildew caused by Sclerospora sacchari Miyake.
• Eye spot caused by Helminthosporium sacchari (Breda de Haan) Butl.
• Yellow spot caused by Cercospora Kopkei Krueg.
• Brown spot caused by Cercospora Longipes Butl.
• Leaf spot caused by Cercospora vaginae Krueg.
• Rust caused by Puccinia kuchnii (Kr.) Butl. and P.erianthi Padwick & Khan.
• Ring spot caused by Letophaeria sacchari Breda de Haan.
• Leaf blotch or spot caused by Helminthosporium halodes Drechsler, H. sacchari and H. tetramera McKinney.
• Root rot caused by Pythium spp.
• Smut caused by Sphacelotheca erianthi.
• Ergot and sugary disease caused by Claviceps spp.
• Root rot caused by Rhizoctonia solani Kuhn and Sclerotium rolfsii Sacc. The symptoms of these diseases are similar to the ones caused by species of the same genus on other hosts.

• Over 50 nematode species belonging to 20 different genera are reported to infect sugarcane in various countries of the world.
• At least 10 have been reported in India.
• Among these the Meloidogyme spp. are important.
• Sugarcane is among the various hosts affected by nematodes in India.
• The crop is damaged by the root-knot nematodes, though several other ecto-parasitic nematodes occur on this host.
• The occurrence of root-knot and other hosts was first established by Rangaswami and his associates during 1958-1960.

• The diseased plants are chlorotic and stunted, and yellow stripes show on the young leaves while older leaves appear healthy.
• Crops at all stages of growth are affected and the symptoms are more prominent during summer months.
• When the roots of affected plants are dug out and examined, they are found to be knotted.
• The young, white roots show much less knotting than the older, wiry ones.
• The knots are usually linear and are found more commonly towards the root tips. They are about 5-8 mm in thickness.
• The nematodes are separated from the infected tissues by the Baermann Funnel technique and examined under the microscope.
• The females measure 400-460mm in length and 45-50mm at the thickest point, oesophagus 40-45mm and tail 30-35mm.
• The males measures 420-460mm in length, 20-25mm in width at the thickest point and oesophagus 55-60mm and tail 30-35mm.
• The cyst is pear shaped, measuring 600-650mm x 380-400mm with a prominent beak.
• The other species of Meloidogyne reported on sugarcane are M. arenaria Chitwood and M. incognita Chitwood, both of lesser importance than M. javanica.

• The nematode eggs persist in soil in cyst form and when the susceptible host is planted, the cyst give rise to the larval forms which invade the root and form the galls.
• There are reports on the exudation of specific chemical substances by the various hosts with either attract or repulse the nematode larvae.
• Once the larvae are inside the host tissue, they feed through the vascular bundles and complete the life cycle.
• They produce the cysts, which protrude from the host roots and remain there until harvest.
• The production of growth regulators such as indole acetic acid in the host tissue is reported to be correlated with the growth promoting and nodule forming effect of the nematodes, as found by Rangaswami and his associates.
• There are over one hundred plant species, belonging to diversified families, which are host plants for M. javanica. No doubt these host plants, particularly the weeds present in sugarcane fields, and the crops used in rotation with sugarcane, play significant roles in the perpetuation and inoculum build-up of the nematode.

• The root-knot nematode can be checked by fumigating the soil with a nematicide such as Nemagon or D.D.T
• The soil must be opened up soon after crop harvest.
• The chemical fumigant should be injected into the soil as per the directions given by the manufacturer after which the soil is kept covered with a tarpaulin or plastic sheets for a week or two, if necessary.
• The fumes permeate the soil, killing the nematode larvae and cysts, and other organisms as well.
• The soil is safe for planting in 2-3 weeks after fumigation.
• In some countries crop rotation with marigold reduces the nematode population.
• The effect of such plants or their plant roots exudates on the nematode population, and the inter-relationships of other soil microbial populations with the nematode, have to be investigated in detail to understand this complex phenomena has to evolve effective control measures.
• Certain nematophagous fungi like Catenaria vermicola, Arthrobotrys conoides Drech. and Dactylella deodycoides Drech. are present in soils, and this might help in reducing the nematode population.
• Besides Meloidogyne javanica and other species of Meloidogyne which cause root-knot symptoms, Pratylenchus sp., Paratylenchus macrophallus deMan, Trichodorus sp., Rotylenchus sp., Tylenchorhynchus sp, Xiphinema sp., Rotylenchus sp. and Hoplolaimus coronatus Cobb have been reported by Kishan Singh on sugarcane in some parts of India.
• More detailed studies are needed on the disease symptoms, life cycle of the nematodes, nature and estimation of damage and control measures.
• A phanerogamous parasite affecting the roots of sugarcane has also been reported from some parts of India.
• It is identified as Striga euphrasioides Benth.
• This is a partial root parasite, growing up from the roots to form leafy shoots.
• The parasite can synthesize carbohydrates through the green chlorophyll pigments in the leaves but for its other nutrients it depends on the host root.
• It is usually controlled by pulling out the shoots before flowering and seed set.
• Spraying weedicides like 2-4, D will kill the parasite, without affecting the sugarcane plant appreciably.

• The disease spreads mainly through planting material, setts should be selected from healthy plants.
• Treating the seets in hot water at 500C for about 2 hours gives 100 per cent control and has become a regular practice in many countries.

• In India the disease was identified during the early thirties of this century and has been reported since then from almost all the sugarcane tracts of the country.
• The intensity of the disease and the loss in crop yield vary considerably, depending upon the host variety and climatic conditions.

• Sugarcane Mosaic Virus (Marmor sacchari).
• The virus is present in abundance in the chlorotic lesions of the affected leaves.
• It causes varying degrees of destruction of the chlorophyll, and hence the chlorotic symptom.
• The virus has been purified and studied in detail for its physical and chemical properties.
• Purified virus particles are rods, measuring the range of 650-770 x 12-15 mm.
• Several strains of the virus, designated as A, B, C, D, E, F and G and a few sub-strains have been differentiated, based on their physical properties and virulence.

• The disease spreads readily through infected canes used as seed setts. It is also transmitted from plant to plant by the aphids Rhopalosiphum maidis (fitch) and Hysteroneura setariae Thos.) and by the green bug Toxoptera graminum (Rond.)
• The virus is a non-persistent type in its vectors.
• In India R. maidis is the main vector; thogh T. graminum (Schizaphis graminum) was demonstrated to be a vector of the virus in experimental studies.
• The virus is also sap-transmissible.
• Once the virus is inside the susceptible host tissues, it becomes systemic.
• The incubation period varies from 7 to 20 days, depending upon the host variety and virus strain.
• The virus spreads, both from the leaves to the stem and from the stem to the leaves, and to other shoots in the clump.
• Depending upon the climatic and other environmental conditions and host-pathogen relationships, the symptoms may be prominent or masked.
• In some cases plants have recovered from early infections, due to changed environment and altered physiological condition of the host plant.
• From such plants, healthy shoots may arise from the clump and the newly formed leaves may have no mosaic symptoms.
• In such cases the damage to the crop in reduced yield and sugar content is less.
• Besides sugarcane this virus infected several other cultivated plants, including sorghum, maize and some wild grasses

• In the early years of this disease attempts were made in Java and other countries to completely eradicate it by cutting and burning the diseased plants.
• Later it was realised this not only was not easy to do, but also it was necessary because of the availability of resistant varieties.
• Roguing infected plants and chemical sprays to kill the insect vectors are also advocated.
• However, the most practical method of controlling the disease is to grow mosaic-resistant or, at least, tolerant varieties.
• Introduction of mosaic-susceptible varieties during earlier years, produced at the Sugarcane Research Institute, Coimbatore, in other areas of the world often resulted in devastating damage to the crop.
• This emphasized the need to breed mosaic-resistant varieties.
• At present the newer varieties are invariably tested for resistance to mosaic and other severe disease, before they are released for large-scale cultivation.
• Saccharum spontaneum L. and S. barberi Jesweit carry resistance to mosaic.
• Most of the popular sugarcane varieties under cultivation in India are resistant or tolerant to the disease.
• The occurrence of another virus disease, Ring mosaic, on sugarcane in India was also reported recently.
• It causes ellipitic rings with well developed yellowish or dark green centres.