BACTERIAL,VIRAL & PHYTOPLASMAL

DISEASES OF SUGARCANE AND

THEIR MANAGEMENT

BYAbhijith v

ROLL NO :2012-20-105

INTRODUCTION• Sugarcane is not only cash crop for the growers, but

it is main source of white crystal sugar. It also provides grower with a very good substitute of sugar as ‘gur’ and ‘khandsari’ (brown sugar).

• Sugarcane tops serve as fodder for cattle, baggage and leaf trashes as fuel, stubble and roots as organic manure and crop residues as mulch and compost.

• It may also be kept in mind that sugarcane leaves are used as substrate for the artificial cultivation of edible mushrooms.

• There are many constrain, including the heavy losses, caused by a number of diseases to the sugarcane crop.

• More than 50 diseases are reported in sugarcane, fungi, bacteria, viruses and nematodes cause the most destructive diseases.

• These all diseases are injurious in some areas, in some years and on some plant parts.

FUNGAL DISEASES

WHIP SMUT (Ustilago scitaminea)

Symptoms:

• The affected canes produce long, black whip-like and coiled or curved shoots, which are covered with a thin silvery membrane, containing masses of chlamydospores of the fungus.

• The smutted shoots may arise from the top of the cane or from lateral buds. Later on that membrane ruptures and releases a multitude of spores, which contaminate soil and the standing crop.

• In certain cases, the infected plants remain stunted in growth with increased tillering of little value. The diseased plants are unfit for use.

Perpetuation:

• The disease is carried over from year to year by ratooning or planting sets taken from smutted shoots of cane. Soil borne infection may also takes place, while wind disseminates disease.

Control:

Following measures are suggested for prevention as well as control of the disease:

1) Sets from smutted canes should not be used for planting.2) Seed-sets should be disinfected either in 0.1% mercuric chloride or formaline solution for 5 minutes followed by 2 hours covering under a moist cloth. The other effective chemicals available in market may also be used.3) Hot water treatment of sets at 52°C for 18 minutes can help eliminate the internal infection.4) Smutted plants should be rouged out and burnt before the bursting of the spores.5) Ratooning of the diseases crop should be discoursed.6)Use of resistant varieties should be encouraged. 7) Planting should be done in healthy soil.8) Autumn planting of sugarcane should be avoided.

Rred Rot (Colletotrichum falcatum)

Symptoms: • The disease first

appears as red bright lesions on mid rib of leaves and shows itself as drooping and changing of colour of upper leaves.

• Withering of the leaves proceeds downwards. Usually third or the fourth leaf from the top is affected and shows drying at the tip.

• The pith becomes red and later on brown. In sever cases complete destruction of the stools is brought about.

Perpetuation: • The disease is perpetuated from year to year by planting

sets from infected canes and also through the fungus that remains viable on diseased canes lying in the field or ratooning of the crop.

Control:• Non ratooning and use of resistant varieties are

recommended. Disinfecting of sets with effective and easily available chemicals.

BACTERIAL DISEASES

RATOON STUNTING

• PATHOGEN: Clavibacter xyli subsp. xyl (Xylem limited fastidious bacteria)

• HOST: Sugarcane

SYMPTOMS

• stunted growth of clumps

• reduced tillering, • Thin stalks with shortened internodes and yellowish

foliage (mild chlorosis). • Coryneform Xylem limited fastidious bacteria infects the

vascular bundles of canes . When mature canes are split open, vascular bundles appear discolored.

• In young canes, pink colour in the form of minute pin head like areas near the nodes.

• reduced length, girth and the number of canes per clump

Transmission

• The disease spreads through use of diseased setts. • spreads through cane harvesting implements

contaminated with the juice of the diseased canes. • Maize, sorghum, Sudan grass and Cynodon are some of

the collateral hosts of the pathogen.

Management

• Grow setts from disease free field. • Remove and burn the clumps showing the disease• Sterilization of cutting knives with spirit or any other

antiseptic solution• Hot air treatment of setts at 52˚ C for 8 hours or hot

water treatment at 52˚ C for 2 0 minutes or aerated steam treatment at 50˚ C for 1 hour.

RED STRIPE(Xanthomonas Rubrilineans)

• Symptoms

• Appears in may• Leaves show red streaks

• Control

• Rogue out and bum affected plants if small in number

• Otherwise discard tile whole field

• Fresh sowings are done with resistant varieties in well drained soils

LEAF SCALD( Xanthomonoas albilinean)

• Leaf scald was first recognized as a bacterial disease of sugarcane in the 1920s.

SYMPTOMS

•  The most typical symptom is a white pencil line streak about 1–2 mm wide on the leaf that extends from the midrib to the leaf margin running parallel to the veins

• A diffuse yellow border of varying widths runs parallel to the pencil line streak. The pencil line may have areas of reddish discoloration along part of its length

• later, necrosis develops from the leaf tip or leaf margin, and finally extends the entire leaf (Figure 2). Leaves look burned and curl inward, giving the foliage a scalded appearance, hence the name for the disease

• partial or complete chlorosis of the leaf blade

• Causal Agent

• In the early stages of infection, the leaf scald bacterium is restricted to the xylem elements of the vascular bundles in the white pencil line streaks. It is generally not found in the surrounding chlorotic leaf tissues. A phytotoxin called albicidin has been isolated from chlorosis-inducing strains of X. albilineans. This phytotoxin inhibits chloroplast differentiation and thus disrupts photosynthesis. In the late stages of infection, the pathogen exits the xylem and invades other tissues, causing the appearance of lysigenous cavities in the stal

GUMMING DISEASE(Xanthomonas vasculorum)

• 2ND Disease to be natal

SYMPTOMS

• There are two phases mild and accute the symptoms of mild is on leaves• Yellow stripes with varying length and upto 1/8 of an

inch in width develop from infection site to both the tip and base of leaf following venation

• Sometimes infection passes from leaf to stem by way of leaf sheath and get advanced

• If LS of stem taken slow oozing of yellow red gum from cut ends of vascular part of stem

• If accute• Cavities are formed in softer parts in the vicinity of

growing point• These are filled with gummy material• Chlorosis in the form of white pathes-is a

secondary symptom due to toxin produced by bacteria

TRANSMISSION

• By planting infected setts• The bacteria ooze from infected plant is carried out to

healthy plant by wind,rain through small injuries in leaves

CONTROL

• Growing resistant varities• It is difficult o control disease by eradication or roguing

if advanced

RED STRIPE(Xanthomonas Rubrilineans)

• Symptoms

• Appears in may• Leaves show red streaks

• Control

• Rogue out and bum affected plants if small in number

• Otherwise discard tile whole field

• Fresh sowings are done with resistant varieties in well drained soils

VIRAL DISEASES

SUGARCANE MOSAIC VIRUS (SCMV, Potyvirus group)

Symptoms:

• Mottling of young crown leaves showing a definite pattern of alternating dark and light green coloured patches of varying size and run parallel to the midrib of leaf.

Transmission: Transmitted through mosaic infected sets and an aphid.

Alternate hosts: Maize and sorghum.

Control: Planting virus free sets and avoid ratooning of diseased crop.

PHYTOPLASMA DISEASES

GRASSY SHOOT DISEASE

• Pathogen: Phytoplasma • Hosts: Sugarcane

SYMPTOMS

• proliferation of tillers, which give it typical grassy appearance, hence the name grassy shoot disease.

• The plants appear bushy and ‘grass like’ due to reduction in the length of internodes,

• premature and continuous tillering.

• The leaves of infected plants do not produce chlorophyll, and therefore appear white or creamy yellow.

• The leaf veins turn white (Albino) first as the phytoplasma resides in leaf phloem tissue. include leaf chlorosis,

• no cane formation.

TRANSMISSION

• Transmitted via seed setts/planting material• by phloem feeding vectors as aphids • Phytoplasma infection also spreads through insect

vectors

Management

• Control vector by spraying Malathion or Dimethoate @ 2ml/lt

• Plant disease free setts• Remove and burn the infected clumps periodically• Avoid ratooning in problem areas• Hot Water Treatment (HWT) of setts at 52˚ C for

30min or Aerated Steam Therapy (AST) at 50˚ Cfor 1hr followed by steeping in fungicidal solution of carbendazim @ 0.05% for 15 minutes.

Thank You