RATOON STUNTING DISEASE OF SUGARCANE

RATOON STUNTING DISEASE OF SUGARCANE

Causal Organism: Leifsonia xyli Subsp. xyli

Old- Clavibacter xyli

Vivek Kumar

Student [ B.Sc (H) Agriculture ]

School of Agriculture, GEHU (Dehradun)

 INTRODUCTION:

• The disease is present throughout the sugarcane growing areas of our country. CO 419 variety was worst affected in parts of Karnataka where it was withdrawn from cultivation. The disease appears in both plant and ratoon crop, but more pronounced in ratoon crop.

CLASSIFICATION:

• Domain: Bacteria
• Phylum: Actinobacteria 
• Class: Actinobacteria
• Subclass: Actinobacteridae
• Order: Actinomycetales
• Suborder: Micrococcineae
• Family: Microbacteriaceae
• Genus: Leifsonia 
• Species: Leifsonia xyli  Subsp. xyli

SYMPTOMS:

• Diseased clumps usually display stunted growth, reduced tillering, thin stalks with shortened internodes and yellowish foliage (mild chlorosis).
• When mature canes are split open, vascular bundles appear discoloured.
• In young canes, pink colour is seen in the form of minute pin head like areas near the nodes.
• The disease reduces the length, girth and the number of canes per clump.

           Stunted growth                     

Orange pin head dots on internode

        

ETIOLOGY:

• It infect the xylem (water transport) vessels of the sugarcane plant.
• The bacterium is rod shaped, typically with a slight bend and measures 0.25-0.5 μm by 1-4 μm.
• The organism that causes RSD is, Leifsonia xyli subsp. xyli, a small aerobic and Gram Positive bacterium.
• The genus of the pathogen was previously called Clavibacter.

Leifsonia xyli

Microscopic view

SURVIVAL AND SPREAD :

• The two primary methods of spread of the disease are by planting infected cuttings and by use of contaminated cutting implements.
• The bacterium is highly contagious and can be spread for many metres down a row after a planter or harvester cuts a diseased stalk or plant.
• The recirculating fungicide spray system on planting machines can carry the bacteria and spread the disease.

FAVOURABLE CONDITIONS:

• Infected setts.
• Dense planting.

DISEASE CYCLE:

• The disease spreads through use of diseased setts.
• The disease also 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.

DISEASE MANAGEMENT:

Cultural method:

• Select healthy setts for planting.
• Field should maintain at proper sanitation.
• Ungerminated setts should be removed and fill the gap with new setts which should be treated before planting.

Mechanical method:

• Treat the setts with hot water at 50°C for about 2 hours this gives 100 per cent control. A temperature higher than this would kill the cane and lower temperature than the specified enables the pathogen to survive.
•   Aerated steam therapy eliminates the pathogen from the infected canes. Use of disinfectants to clean seed cutting tools which would reduce the chance of spread of pathogen from the infected to healthy setts.

Chemical method:

• Chemical disinfectants that may be used on cane cutting knives includes, Lysol, Dettol, ethanol, Mirrol and Roccal. Atleast 5 minutes of contact with the cutting surface is needed to assure disinfection.

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GRASSY SHOOT DISEASE OF SUGARCANE

  GRASSY SHOOT DISEASE OF SUGARCANE

        Causal Organism: Candidatus sacchari

 Juhee Kumari

Student [B.Sc(H) Agriculture]

School of Agriculture, GEHU (Dehradun)

INTRODUCTION:

•  The grassy shoot disease (GSD) of sugarcane occurs in most of the Asian countries, affecting sugarcane production to a considerable level.
•  It was first noticed in India in 1919 in Maharashtra. 
•  The disease is caused by grassy shoot phytoplasmas. In India the disease occurs in all the sugarcane growing states.       

CLASSIFICATION:

•  Domain: Bacteria
•  Phylum: Firmicutes
•  Class: Mollicutes
•  Order: Acholeplasmatales
•  Family: Acholeplasmataceae
•  Genus: Candidatus
•  Species: sacchari   

     

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.   

Whitining of leaf

Profuse tillering

            Reduced internodal length  

             

Grassy shoot

             

ETIOLOGY:

•  Phytoplasmas, formely called Mycoplasma like organisms (MLOs).
•  Its large group of obligate, intracellular, wall less, Shape less.
•  It is Gram positive Bacteria.
•  Its found in the Phloem cells of infected plant.
•  Two types of bodies are noticed , spherical bodies of 300-400 nm diameter and filamentous bodies of 30-53 mm diameter in size.   

SURVIVAL AND SPREAD :

•  The grassy shoot disease is primarily transmitted through the diseased seed material (setts) and perpetuated through ratooning.
•  The MLO 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
•  This disease is also transmitted by -

            -Mechanically by cutting knife.
              -Insects (aphids, black hopper).  
-Dodder (root parasite).

FAVOURABLE CONDITIONS:

•  Dense planting.
•  Ratooning.
•  Presence of Insect.
•  Cloudy days.

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.

DISEASE MANAGEMENT:

   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.

References:

Diseases of Field Crops:V.K Gupta & Y.S Paul (2002), Plant Diseases : R.S Singh , Plantix.net , apsjournals.apsnet.org , sugarcane.icar.gov.in , www.cabi.org, researchgate.net , agropedia, springer, eagri.org , agritech.tanu.ac.in , NIPHM, NCIPM.

Thank You!!

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POKKAH BOENG DISEASE OF SUGARCANE

 POKKAH BOENG DISEASE OF SUGARCANE

Causal Organism: Fusarium moniliforme

Vivek Kumar

Student [ B.Sc (H) Agriculture ]

School of Agriculture, GEHU (Dehradun)

INTRODUCTION:

• Pokkah boeng , a Javanese term, which describe a disease as affecting to sugarcane tops, was first reported in Java by Walker and Went in 1886 and later reported by Edgerton (1955) and Martin et.al (1961).
• In india it was observed for the first time in Maharashtra on Co7219 and Coc671 varieties.
• The occurrence of the disease has been recorded in almost all the cane growing countries in the world.
• 3 to 7 month old crop growing vigorously is more susceptible to infection than older cane.

CLASSIFICATION:

•  Kingdom : Fungi
•  Division : Eumycota
•  Sub-division : Deuteromycotina
•  Class: Hypomycetes
•  Order: Hypocreales
•  Family: Nectriaceae
•  Genus : Fusarium 
•  Species : moniliforme

SYMPTOMS:

The general symptoms of Pokkah boeng are mainly of three types-

• Chlorotic Phase
• Acute Phase or Top-Rot Phase
• Knife-cut Phase

Chlorotic Phase-

• Chlorosis at the base of the young leaves and occasionally on the other parts of the leaf blades.
• Frequently, wrinkling, twisting and shortening of the leaves accompanied the malformation or distortion of the young leaves.
• The base of the affected leaves is seen often narrower than that of the normal leaves.

Acute Phase or Top-Rot Phase-

• The most advanced and serious stage.
• Leaf infection sometimes continued to downward and penetrates in the stalk by way of a growing point.
• In advanced stage of infection, 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.

Knife-cut Phase-

• The symptoms of knife-cut stage are observed in association with the acute phase of the disease 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, This is an exaggerated stage of a typical ladder lesion of a Pokkah boeng disease.

ETIOLOGY:

• Mycelium - Septate, branched, light pink Conidia.
• Macro conidia - boat shaped, hyaline, long septate, pointed at tip Micro conidia - small, curved, unicellular. 
• Conidiophores - simple, slender, short, produced in sporodochium. 
• Chlamydospore - spherical, thick walled.

Mycelium and spores of Fusarium moniliforme

 (Microscopic View)

                                                             

Fusarium

                                                                                 

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.

DISEASE CYCLE: 

• The fungus is soil-borne and remains in the soil as Conidia & Chlamydospore
• The disease is primarily transmitted through infected seed pieces.
• The secondary spread is aided by wind, rain and irrigation water.

DISEASE MANAGEMENT:

• Select the seed material from the disease free plots.
• Avoid the practice of rotooning in diseased fields.
• Burn the residue & stubbles in the fields.
• Grow coriander or mustard as a companion crops in early stages of crop.
• Dip the seats in 0.05%carbendazim for 15 minutes.
• Grow resistant varieties.
• Crop rotation.
• Managing root borer.
• Avoiding prolonged drought and water logging.
• Apply bulk manure.
• Apply Trichoderma in FYM.
• Spray Carbendazim, Propiconazole or Hexaconazole.

Thank You !!

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WILT DISEASE OF SUGARCANE

 WILT DISEASE OF SUGARCANE

Causal Organism: Fusarium sacchari

Old: Cephalosporium sacchari

Vivek Kumar & Juhee Kumari

Student B.Sc.(H) Agriculture

School of Agriculture, GEHU (Dehradun)

INTRODUCTION:

The wilt disease of sugarcane was first reported from Bihar in 1906, and now it is a common and destructive disease occurring in many parts of our country such as U.P., Bihar, Haryana, Punjab, Gujarat, Andhra Pradesh, and Tamil Nadu.

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

This disease caused great damage to sugarcane crop in the Deccan Plateau and to a lesser extent in other areas during 1965-67 and, because of it the sugar industry in the country was paralysed. This disease, however, often occurs in association with the red rot disease of sugarcane and is only second to red rot in causing economic loss to the crop.

Wilt of sugarcane appeared in epidemic form in many districts in Tamil Nadu during 1955-56 and, as a result, certain sugarcane varieties like Co419, Co449, Co453, Col 122 were withdrawn from cultivation. However, the disease is also known to occur in Bangladesh, Pakistan, Argentina, Philippines, South Africa, USA, Barbados, Trinidad, Columbia, Zimbabwe, and Mexico.

CLASSIFICATION:

  Kingdom : Fungi

  Division : Eumycota

  Sub-division : Deuteromycotina

  Class: Hypomycetes

  Order: Moniliales

  Family: Moniliacease

  Genus : Fusarium 

  Species : sacchari 

SYMPTOMS:

• The first symptoms of the disease become apparent only when the plant has grown for about 4-5 months.
• Then gradual yellowing and drying of foliage, shrinkage/withering of canes.
• If the affected canes are cut and examined, the pith will be Light to dark purplish or brown discolouration of ground tissue, pithiness and boat shaped cavities in the middle of the internodes.
•  A characteristic disagreeable odour is also associated with this disease.
•  Often a cottony white mycelium is seen in the pith region.

Yellowing of leaves

      Boat shaped cavity on the internode

Reddish discolouration in cane 

Shrinkage of cane

ETIOLOGY:

•  The fungal mycelium is hyaline, septate and thin walled. 
•  The conidiophores are simple or branched and produce single celled, hyaline, oval to elliptical microconidia. 
•  Macroconidia are straight with 3-5 septa measuring 27-73 × 3.4-5.2 mm.
•  Blastoconidia are either straight, sickle shaper or pike shaped with 2-3 septae. Moreover will be found as elliptical cell shaper structure with 1.-43x3.0-4.5 mm in size.

Conidiophores

Fusarium sacchari

                                     

                      

FAVOURABLE CONDITIONS:

•  High day temperature (30-35˚C).
•  Low humidity (50-60%).
•  Low soil moisture and alkaline soils.
•  Excess doses of nitrogenous fertilizers.

DISEASE CYCLE: 

• The fungus is soil-borne and remains in the soil as saprophyte for 2-3 years.
• The disease is primarily transmitted through infected seed pieces.
• The secondary spread is aided by wind, rain and irrigation water.

DISEASE MANAGEMENT:

   Cultural method:

• Selection of healthy seed setts from disease-free area for planting
• Grow resistant varieties like Co 617 and B.P.17 are more resistant than other varieties
• Crop rotation, managing root borer, avoiding prolonged drought and water logging and hygienic practices.

  Biological method:

• Many species of Streptomyces and Bacillus are known to be the natural antagonists of the wilt pathogen. However their commercial has not been worked out.

  Chemical Method:

•  Dipping the setts in 40 ppm of boron or manganese, or spraying the plants with either of these minor elements reduces the disease intensity.
•  Sett treatment with fungicide like Bavistin, 0.1 per cent before planting.
•  Apply carbendazim @ 2gm/lit of water at the root zone area and same as follow at 15 days interval.

References:

Diseases of Field Crops:V.K Gupta & Y.S Paul (2002), Plant Diseases : R.S Singh , Plantix.net , apsjournals.apsnet.org , sugarcane.icar.gov.in , www.cabi.org, researchgate.net , agropedia, springer, agritech.tanu.ac.in , NIPHM, NCIPM

THANK YOU....

if any suggestion than please comment below in comment section 🙏