Diseases of sugarcane and their management (गन्ने के रोग एवं उनके रोकथाम)

1. WELCOME

2. Diseases of Sugarcane
(Saccharum officinarum)
Dr. Shivam Singh
Assistant Professor
Department of Plant Pathology
School of Agriculture, LPU

3. Important diseases of sugarcane
1. Red rot: Colletotrichum falcatum
2. Whip smut: Ustilago scitaminea
3. Pokkah Boeng: Fusarium moniliformae
4. Ratoon stunting: Clavibacter xyli
5. Grassy shoot: Phytoplasma

4. 1. Red rot
Causal organism: Colletotrichum falcatum
Perfect stage: Glomerella tucumanensis
Symptoms
• Typical symptoms of red rot are observed in the
internodes of a stalk by splitting it longitudinally.
• The presence of cross-wise white patches are the
important diagnostic character of the disease.
• The diseased cane also emits acidic-sour smell. As the
disease advances, the stalk becomes hollow and
covered with white mycelial growth.
• The pathogen also produces tiny reddish lesions on the
upper surface of leaves with dark dots in the centre.

6. Pathogen
• The pathogen produces specialized structures known as
acervuli, which support profuse sporulation.
• Conidiophores are closely packed inside the acervulus,
which are short, hyaline and single celled.
• Spores (conidia) are hyaline (clear), oblong, single-celled
and produced in a slimy matrix.
• Fungus also produces large number of globose and dark
brown to black perithecia with a papillate ostiole.

10. Survival and Spread
• They rely heavily on water, particularly rainfall,
for dissemination.
• The fungus is sett-borne and also persists in the soil
on the diseased clumps and stubbles.
Favourable Conditions
• Successive ratoon cropping.
• Water logged conditions and injuries caused by
insects.

11. Management
• Use disease free setts.
• Hot water treatment at 52˚C for 10 mins.
• Use of resistant varieties viz., Co 86032, Co 86249,
CoSi 95071, CoG 93076, CoC 22, CoSi 6 and CoG 5.
• Cut ends and setts should be dipped in 1% Bordeaux
mixture.
• Use fungitoxic chemicals like Bavistan, Benomyl,
Topsin and Aretan @0.1% for 18 min. at 52ºC for
dipping setts.

12. 2. Whip smut
Causal organism: Ustilago scitaminea
(Syn. Sporisorium scitamineum)
Symptoms
• Affected plants are stunted and the central shoot is
replaced by a long whip like, dusty black structure,
several feet in length.
• In early stages this structure is covered by a thin
silvery white film, which rupture exposing the mass of
dense, black dust.

14. Pathogen
• The fungal mycelium spores are echinulate, light brown
and spherical, measuring 6.5 – 8.5 µ in diameter.
• They germinate readily in water, producing 2-3 celled
promycelia.
• Sporidia arise terminally or laterally and are hyaline,
thin walled, single celled and elliptical to linear.

15. Disease cycle
• Teliospores may survive in the soil for long periods, upto
10 years.
• The smut spores and dormant mycelium also present in
or on the infected setts.
• The primary spread of the disease is through diseased
seed-pieces (setts) and also present in soil, which cause
soil-borne infection.
• The secondary spread in the field is mainly through the
smut spores developed in the whips, aided by air currents.

17. Management
•Use disease free setts.
•Avoid ratoon cropping.
•Diseased clumps and setts must be uprooted.

18. 3. Pokkah boeng
Causal organism: Fusarium moniliforme or
F. andiyazi or F. sachhari or F. subglutinans
Symptoms
The general symptoms of Pokkah boeng are mainly of
three types:
1. Chlorotic Phase: The earliest symptom is a chlorotic
condition towards the base of the young leaves and
occasionally on the other parts of the leaf blades.
Frequently, a pronounced wrinkling, twisting and
shortening of the leaves accompanied the malformation or
distortion of the young leaves.
First reported from Java in 1896.

19. 2. Acute Phase or Top-Rot Phase: The most advanced
and serious stage is a top rot phase.
• The young spindles are killed and the entire top dies.
• Leaf infection sometimes continued to downward and
penetrates in the stalk.
• Later, the entire base of the spindle and even growing
point showed a malformation of leaves, pronounced
wrinkling, twisting and rotting of spindle leaves.
• Red specks and stripes also developed.
3. Knife-cut Phase: It is characterized by one or two or
even more transverse cuts in the rind of the stalk /stem
in such a uniform manner as if, the tissues are removed
with a sharp knife.

20. Chlorotic Phase

21. Top Rot Phase

22. Knife-cut Phase

23. Survival and spread
This is an air-borne disease and primarily transmitted
through the air-currents and secondary transmission is
through the infected setts, irrigation water, splashed
rains and soil.
Favourable conditions
20-30°C temperature and the average relative humidity
higher than 70 to 80% with a cloudy weather, drizzling
rains favors the growth of pathogen.

24. Management
• Removal of plant debris.
• Use of resistant varieties.
• Spraying of different fungicides like
Bavistin (0.1%) or Blitox (0.2%) or
Copper oxychloride or Dithane M-45
(0.3%).

25. 4. Ratoon stunting
Causal organism: Clavibacter xyli
(Syn. Leifsonia xyli)
Symptoms
• The affected plants are stunted, the stunting being most
severe in stubble and ratoon crops.
• In infected stocks, the presence of pin head like
orange coloured dots of bacteria on the internal soft
tissue in the nodal region.
• The setts taken from diseased plants germinate poorly
and the few shoots that are emerged grow very slowly.

27. Etiology
• Colonies on semi-solid media are circular with
entire margins, convex and non-pigmented.
• They are small, thin and rod shaped.
• Non-motile.
• Gram-positive.

28. Management
• Planting of healthy and disease free seed cane.
• Growing resistant varieties.
• Hot water treatment of the seed cane @51°C
for 2-3 hours.
• Chemical disinfectants that may be used on
cane cutting knives includes, Lysol, Dettol,
ethanol, Mirrol and Roccal.

29. 5. Grassy shoot
Causal organism: Phytoplasma (MLO)
Symptoms
• Initial symptom appears in the young crop of 3-4
months age as thin papery white young leaves at the
top of the cane.
• Later, white or yellow tillers appear in large number
below these leaves (profuse tillering).
• The cane becomes stunted with reduced internodal
length with axillary bud sprouting.
• Cane formation rarely occurs.

31. Etiology
• Two types of bodies are seen in ultrathin sections of
phloem cells of infected plants.
• The spherical bodies of 300-400 nm diameter
and filamentous bodies of 30-53 nm diameter.
Disease cycle
• The primary spread of the phytoplasma is through
diseased setts and cutting knifes.
• The pathogen is transmitted secondarily by
aphids viz., Rhopalosiphum maydis, Melanaphis
sacchari and M. idiosacchari.
• Sorghum and maize serves as natural collateral hosts.

32. Management
• Eradication of diseased parts as soon as symptoms
are seen.
• Avoid selection of setts from diseased area.
• Pre-treating the healthy setts with hot water @52°C
for 1 hour before planting
• Treating them with hot air @54°C for 8 hours.
• Spraying the crop twice a month with insecticides.
• Application of tetracyclin.

33. Other diseases
1. Sett Rot/ Pineapple disease: Ceratocystis paradoxa
2. Red stripe/Top rot: Pseudomonas rubrilineans
3. Gummosis: Xanthomonas compestris pv. vasculorum
4. Leaf scald: Xanthomonas albileneans
5. Sugarcane Mosaic: Sugarcane mosaic potyvirus