17.red rot of sugsrcane and its management practices

red rot od sugarcane

1. Red rot of Sugarcane

2. Etiology
•Caused by Collectotrichumfalcatum, a facultative
saprophyte.
•sexual stage known as Glomerellatucumanensis
•Mycelium: both intracellular and intercellular
•Asexual fruiting bodies known as acervuli
•Conidiophores: linear or club shaped, hyaline,
septate
•Conidia: elongated, single celled, thin walled,
uninucleate, colourless, sickle shaped (Falcate)
with granular protoplasm with a large oil globule
•Chlamydospores: thick walled, greenish black
•produce a phytotoxic metabolite-anthroquinone
compound

3. •Thefirstsymptomsofthediseaseareseen
whenthevegetativegrowthoftheplantis
stoppedandsucroseformationbegins,i.e.,
afterrainyseason.
•Thepathogencanattackanypartofthe
sugarcaneplanti.e.stalk,leaf,budsor
roots.
•Theleaveswithergraduallydownwards
withtheprogressofthedisease.
•Usuallythethirdorthefourthleaffrom
thetopisaffectedandlateronthewhole
crownwithersanddroops.
•Ifthefungalsporesentertheleafsheath
throughtheleafmidrib,thenreddishspots
canbeseenonthebacksideoftheleaf
midribalso.

4. Symptoms
•Typical symptoms of red rot are observed in the
internodes of a stalk by splitting it
longitudinally.
•Reddening of the internal tissues which are
usually elongated at right angles to the long
axis of the stalk.
•With the advancement of disease, the stalk
becomes hollow and covered with white
mycelial growth.
•Later on the rind shrinks longitudinally with the
protrusion of minute black, velvety fruiting
bodies.
•The infected cane emits acidic-sour smell while
its juice emits alcoholic smell.

5. Disease cycle & epidemiology
•Theperpetuationofredrotisthroughinfectedsetts/canes,diseased
stubble/debrisandbyrestingpropagulesinthesoil.
•Thepathogenattacksthecaneplantfromtheverybeginning,i.e.,germination
andcausegerminationfailureorcausedeathofgerminatedseedlings.
•Thesecondarytransmissionofthefungusduringmonsoonismediated
throughirrigation,rainwater,rainsplash.
•Thepathogenmainlyinfectscanesthroughnodesandmainportalofentryare
leafscar,growthring,rootprimordiaandbuds.
•Thepathogencanalsoenterthestalkthroughrootlets,growthcracksandcut
endsofthesetts.

6. •Mean temperature range of 29.4 to 31°C is optimum for the
development of the disease.
•pH 5-6
•Drought conditions during the initial growth phase.
•High atmospheric humidity (90%).
•Water-logged conditions of the soil.
•Lack of cultural practices that result in the growth of weeds.
•Continuous cultivation of same variety in the field.
•Presence of susceptible varieties in the surroundings.

7. Management practices
•Cultural method:
•Disease free seed nursery should be established in each farm and farmer’s field.
•To minimisethe soil borne inoculum, crop rotation should be adopted by growing some
other crop for 2-3 years.
•Crop debris, trash and stubble should be burnt prior to planting
•Extremely dry and wet soils should be avoided
•Ratooning should not be done in case of heavily infected plant crops.
•Flow of irrigation water from diseased to healthy plants should be discouraged to avoid
the spread of disease through water medium.
•Long setts should be used for planting. Three or four budded setts are very suitable seed
setts for the control of soil born inoculums of red rot.
•Growing of recommended resistant and moderately resistant varietiesviz., Co
86032, Co 86249, CoSi95071, CoG93076, CoC22, CoSi6 and CoG5

8. •Physical method:
•Removal of the affected clumps at an early stage and soil drenching withCarbendazim
50 WP (1 gm in 1 litreof water)
•The cut ends and entire setts should be dipped in a fungicide solution, such as one per
cent Bordeaux mixture.
•Biological method:
•Red rot disease of sugarcane was observed to be biologically controlled through
Trichoderma harzianum, T. virideand Pseudomonas spp.
•Botanical:
•Ocimum, Ginger, Onion and Garlic were found to inhibit the mycelial growth.
•Use of essential oils, viz. Peppermint oil, Menthaoil, Geranium oil, Patchouli oil and
Palmarozaoil were effective in inhibiting the growth of mycelia.
•Leaf extracts of Curcuma domesticaand Datura metelinhibited the conidial as well as
mycelial growth.

9. •Chemical method:
•Adopt sett treatment with Carbendazimbefore planting (Carbendazim50 WP (0.5
gm in 1 litreof water) along with 2.5 kg of Urea in 250 litreof water.
•Soaking of sugarcane setts in 0.25% suspension of thiophanatemethyl for 24 h
before planting was found to be effective in controlling debris-borne infection.
•Dip treatment of setts in Agallal(0.5%) for 15 min was found effective.