.

Dr. S.P.Mishra Professor

Dept. of Plant Pathology College of Agriculture,

Rewa

STUDY OF DISEASES OF

SUGARCANE

RED ROT OF SUGARCANE

1.The disease RED ROT firstly notic by Went in year 1893.

2.During 1939-1942it caused heavy losses in Bihar and U.P.

3.Butler and his associates in India investigated the disease in great detail during 1914-1918.

Red spots on the midrib

of the upper leaf surface

develop pale yellow to

white centres, merging

to cover the length of

the leaf. Similar spots

also occur on the leaf

blades.

1.The hyphae are inter and intracellular, thin, septet, hyaline in the beginning turning to dark at maturity.

2.The hyphae produce large number of Chalmydospores in the pith. This can survive in soil for a long time.

3.Thick-walled hyphae, occasionally from dark-green or brown stroma, which develops conidiophores at the epidermis .

4.Long hair like rigid setae,100-200um long develop around in the stroma.

5.This is the developing acervulus.

Microscopic view of a single spore mass shows the crescent (the curved

sickle shape of the waxing or waning moon.) moon-shaped spores which

spread to other plants to cause new infections.

6.These acervuli have conidiospores which are small,aseptate,20X8 um.

8.From the vegetative mycelium, conidia produced.

9.Conidia are hyaline, unicellular, falcate or sickle-shaped and some times fusoid (Like macro conidia of Fusarium) measuring 16-48X4-8um with oil globule.

Symptoms

Symptoms 1.first symptom of red rot in the field is

discoloration of the young leaves.

2.The tissues are reddened throughout

the basal portion, especially the vascular

bundles, which are intensely red.

3.In the infected plants the leaves show

symptoms in the form of dark red lesions

in the midrib, which elongate, turning

Blood-red With dark margins and later

on with straw- colored centers.

Transmission

Primary transmission through soil

and diseased sets, while the

secondary transmission through

air, rain splash and soil.

The fungus also persists in the soil on diseased clumps and dry leaves left in the field after harvest.

If the conidia settle on the leaves they germinate.

Stem infection takes place through insect bores and root primordial.

The soil-borne fungus also enters the healthy sets through cut-ends, and causes early infection in the shoots.

MANAGEMENT

1.The cut-ends, and preferably the entire sett,

should be dipped in a fungicide solution, such as

one per cent Bordeaux mixture, to protect it from

invasion by soil-borne pathogen

. 2.Dipping setts in fungitoxic chemicals like

Bavistan, Benomyl, and Aretan at 0.1 per cent

for 18 min. at 520C gave almost complete

elimination of rot infection.

By the growing of resistant varieties

Co.6806

Co.62198

Co.776

Co.975

Co.8014

Here Co. denotes Coimbatore

Pre disposing (environmental) factors

Mono-culturing of sugarcane

Continuous ratooning

Dry weather during tillering stage

favours the disease

PATHOGEN: PHYTOPLASMA

•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.

• This disease appears in isolated clumps.

Grassy shoot disease

Cultural method:

Growing resistant varieties viz., Co 86249, CoG 93076 and CoC 22

Avoid ratooning if Grassy Shoot Disease incidence is more than 15 % in

the plant crop

If disease symptoms are visible within two weeks after planting, such

plants can be replaced by healthy plants.

Uprooted infected plants need to disposed of by burning them.

Physical method:

Rogue out infected plants in the secondary and commercial seed nursery.

Treat the setts with aerated steam at 50°C for 1 hour to control primary

infection.

Treating them with hot air at 540C for 8 hours and spraying twice a month

with aphidicides.

Chemical method

Spray dimethoate @ 1ml in 1 litre of water to control insect vector

Apply pesticide methyl-demeton @ 2ml/lit of water for controlling aphids.

Causal Organism: Cephalosporium sacchari Class: Deuteromycetes

Order:Moniliales

Family:Moniliacease

1. This is one of the early known diseases of sugarcane in India.

2. It was first reported by Butler and Khan in 1913, from North India.

3. 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

This is an imported disease of

sugarcane and common in Vishakapatnam

and Nizamabad , MP districts and Shrilanka.

The disease occurs singly or in

combination with red rot.

The disease is more is wilt sick soils and in

alkaline soils.

Moisture stress aggravates the disease.

The first symptom of the disease is

visible in the canes of 4-5 months ago.

The canes may wither in groups.

The affected plants are stunted with

yellowing and withering of crown leaves.

The midribs of all leaves in a crown

generally turn yellow, while the leaf

lamina may remain green.

The leaves dry up and stem develop

hollowness in the core or pith.

The pith shows reddish discoloration with

longitudinal red streaks passing from one

internodes to another.

In severe cases, spindle shaped cavities

tapering towards the nodes develop in

each internodes.

The canes emit a disagreeable odour, with

lot of white mycelial threads of the fungus

covering the cavity.

Weight gets reduced due to hollow canes.

WILT DISEASE

•The fungal mycelium is hyaline, septate

and thin walled. The fungal mycelium

are 4-30 x 3-4micron meter.

•The conidiophores are simple, slender or

swollen on which hyaline, single celled,

hyaline, oval to elliptical microconidia

collecting in a slime drop. Macroconidia

are not produced.

High day temperature 30-35dc,

humidity 50-60percent,

low soil moisture, alkaline soils

and excess doses of nitrogenous

fertilizers.

1. The fungal mycelium is abundant in the infected canes.

2. The hyphae are hyaline, thin walled and septate.

3. They produce numerous microconidia on simple or

branched, lateral or terminal hyphae, but NO

macroconidia are produced.

4. This is an important character which is distinct 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 septa.

5. Conidia readily germinate to produce single germ

tubes.

6. 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.

7. Root formation in such setts may be very poor. The fungus can also survive in soil as a saprophyte for 2-3 years.

8. Near-neutral and alkaline soils are favoured by the fungus. The perfect stage is not known.

Select the seed material from the

disease free plots.

Avoid the practice of rationing in

diseased fields.

Burn the trash and stubbles in the

field.

Grow coriander or mustered as a

companion crop in the early stages

of crop.

Treat the sets in hot water at 50dc for

2hrs followed by dipping in 0.05 %

Carbendazim for 15 min.

Dip the sets in 40ppm Boron or

Manganese for 10min.

Avoid alkaline soils for growing the

crop

Grow resistant varieties like CO 617

and BP 17.