Indian Phytopath. 55 (2) : 173-177 (2002)

Diseases of ginger and their control withTrichoderma harzianum

P.P. RAJAN1, S.R. GUPTN, Y.R. SARMN and GVH. JACKSON4

Ginger Disease Task Force Laboratory, Tadong, Gangtok, Sikkim 737 102

ABSTRACT: Ginger (Zingiber officina/e Rosc.), is the second most important cash crop of Sikkim. Diseasesare important production constraints and often associated with Ralstonia (Pseudomonas) solanacearum,Pythium spp., Fusarium oxysporum and Praty/enchus coffeae. Pathogenicity experiments conducted,showed the involvement of Pythium sp (soft rot), Fusarium oxysporum (dry rot) and R.solanacearum (wilt)and also noticed that, Praty/enchus coffeae increased the severity of infection along with F.oxysporum.From the indirect pathogenicity experiments, the specific chemicals, targeted to particular pathogensensured the involvement of different pathogens as well as effectiveness of chemicals on control of gingerwas diseases. A biocontrol agent, T.harzianum, isolated from Sikkim was found effective in control of gingerdiseases substantially.

Key words: Pythium sp., Fusarium oxysporum, Ralstonia solanacearum, fungicides, nematicide,Trichoderma harzianum

Ginger (Zingiber officinale Rosc.), is the secondmost important cash crop of Sikkim, after largecardamom and is widely grown by small holderson about 4500ha. It is cultivated as a monocrop oras intercropped with maize and mandarin orange.Production of ginger in this hilly state is hamperedby different diseases and pests. During the cropseason, foliar yellowing and wilting are moreconspicuous and at the time of harvest, dry rotand rotten rhizome are noticed which reduce themarket value of the produce and makes it unfit forseed purpose. Diseases in the field were oftenassociated with Ralstonia (Pseudomonas)solanacearum Smith (Yabuuchi), Pythium spp.,Fusarium oxysporum Schlecht. and Pratylenchuscoffeae (Zimmerman) Filipjev & Schu.Stekh.

For correspondence: raL 15465@yahoo.com;rajanpp35@hotmail.com1.3 Indian Institute of Spices Research,

Calicut 673 0122 Department of Horticulture, Govt. of Sikkim,

4 24 Alt Street, Queens Park, NSW 2022, Australia

Involvement of Fusarium oxysporum withrhizome rot of ginger in Queensland was reported(Teakle, 1965). In India, Fusarium yellows hasbeen reported from Madhya Pradesh (Haware andJoshi, 1973) and Presence of Meloidogyneincognita and Pratylenchus coffeae in ginger yielddecline has been reported by Kaur et al., 1989.

Present study was undertaken to study theeffect of different ginger pathogens on severity ofdisease in Sikkim. Different pathogenic fungal andbacterial cultures, isolated from differentagroclimatic regions of Sikkim were tested for theirvirulence and used for pathogenic studies. Anumber of antagonistic fungal and bacterial Isolateswere obtained from different parts of Sikkim andscreened against ginger pathogens. One isolate ofTrichoderma harzianum was found most promisingfrom initial screening which was mass multipliedand tested against above-mentioned pathogens,in pot culture.

MATERIALS AND METHODS

Different ginger pathogens viz; Pythium sp.,Fusarium oxysporum and R.solanacearum were

174 Indian Phytopathology

isolated from infected ginger. For isolation ofPythium, P10VP (Tsao and Ocana, 1969), forFusarium oxysporum, Potato Dextrose Agar (PDA)and for R.solanacearum, selective medium (TTC-Kelman,1954) were used. Pythium sp., F.oxysporum and R.solanacearum were purified andstored in PDA slants. Pratylenchus coffeae wasisolated from ginger rhizomes with dry rotsymptoms. Cortical tissues were collected fromnematode infested area as peelings and blendedwith the help of a mixer. The ginger tissuesuspension was passed through nematologicalsieves (100 and 400) and kept for extraction.Nematodes were collected and washed with steriledistilled water 4 times to avoid other contaminants.To avoid bacterial and fungal contamination,nematode suspension was passed through 0.1%mercuric chloride and streptomycin solutions andwashed 4 times with sterile distilled water. Thesterile nematodes were cultured on carrot callus,incubated at 20°C for one month and used forinoculation. The fungal pathogens were massmultiplied in potato - dextrose broth, while thebacterium R. solanacearum was multiplied innutrient agar (Hi-media).

Two month old ginger plants grown in plasticbuckets containing sterile soil, were inoculatedwith respective pathogens. Before the applicationof pathogens, upper layer of soil (around the collarregion) was removed. For fungal pathogens, themycelial suspension (CFU = 23 x 104/ml for Pythiumand 28 x 104/ml for Fusarium oxysporum) wasapplied at the collar region @ 75ml/pot and forbacteria, R.solanacearum suspension (CFU= 1.3x 10B/ml) was applied at the collar region @ 30ml/pot and covered with soil. For nematodeinoculation, nematodes were applied @ 200nematodes/pot. Wherever the combinations ofdifferent pathogens were used, equal quantity ofeach inoculum was used. For each treatment 8replications (eight pots with 3 ginger plants in eachpot) were maintained in Randomized Block Design(RBD). For comparison, eight pots with 3 gingerplants each were maintained as control. All thepots were irrigated daily with boiled-cooled water.Infected seed lots were collected from field andpresence of all four pathogens was confirmed by

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the methods already described. Before planting,the seed lots were treated with different chemicalslike Ridomil Mancozeb-WP, carbendazim (Bavistin),copper oxychloride (Fytolan) and phorate (Thimet).Seed )pieces were treated with the chemicalsolutions for half an hour and for phorate(nematicide) treatment, 15g of phorate granuleswere applied on the surface of seed pieces, bygentle mixing seed with phorate. The remaininggranules were added into the respective bucketswhile planting.

Wherever the fungicides and nematicide wereapplied together, the seed pieces were treatedwith respective chemical first and followed bynematicide. Wherever, the combination of differentfungicides used, solution of different fungicideswas prepared and used as seed treatment. Secondand third round application of fungicides asdrenching was done two and three months afterplanting. For comparison, healthy seed with hotwater treatment (51°C for 10 minutes), infectedseed with hot water treatment and infected seedalone were also included in the treatments. Foreach treatment, 8 replications (8 pots with 3 plants/pot) were maintained and arranged in RBD.

From the dual culture studies, one isolate ofTrichoderma harzianum was found effective againstboth the fungal pathogens iPytnium sp. andFusarium oxysporum) and this efficient isolatewas used for the pot culture study.

The moistured (100 ml/250 g) broken wheatgrains filled in poly propylene bags (8x12') @250g/bag were sterilized at 121°C and 151bpressure for one hour. Spore suspension of T.harzianum was prepared in sterilized water &filtered through sterilized muslin cloth. The sterilizedwheat grains were inoculated with sporesuspension of T.harzianum @ 5ml/bag with thehelp of a hypodermic syringe. Inoculated bagswere incubated at room temperature for 15 days.Colony forming units (CFU) at the time ofapplication were as 9.9 x 10B/g. The biocontrolagents (BCA) inoculum was incorporated into thesoil at the time of planting and applied @ 50g/pot.The pathogens were incorporated into the soil twomonths after planting as described earlier.

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RESULTS AND DISCUSSION

Symptoms of various diseases which appearedon artificially inoculated plants vary very muchsimilar to the symptoms appearing in the fields.Tillers with disease symptoms were removed withrhizome and presence of pathogens was confirmedby isolating them using appropriate culture media.

First symptoms of R. solanacearum infectedplants were, downward curling of leaves and goldenbrown/rusty brown discoloration seen on olderleaves. The symptoms developed after about 12days of inoculation and wilting occurred after 15days of inoculation. In Pythium sp. inoculatedplants, disease symptoms, as foliar yellowing frombottom to top and disintegration of soft rhizometissues appeared after about 13 days of inoculation.Fusarium infection resulted in foliar yellowing(golden yellow), especially at margins of leaf,which, progressed from bottom to top. The initialsymptom were noticed on plants at about 45 daysafter inoculation. The plants wilted andsubsequently death of the plants was observed.But there was no sudden death of the plantsnoticed where P.coffeae alone was applied, thoughthere was yellowing and little decay of rhizome.When P. coffeae was applied along withF.oxysporum, the disease severity was increased,it proved the involvement of nematodes onaggravation of disease along with fungal pathogen.

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The present study supported the earlier findingsof Lum (1973), who conducted a pathogenicitystudy with R.solanacearum by cross inoculationtechnique and proved the pathogenicity ofR.solanacearum on bacterial wilt in ginger. Samueland Mathew (1983) could prove that, bacterial wiltin ginger could aggravate in the presence ofnematodes. Pegg et al. (1974) proved theinvolvement of nematodes on aggravation ofstorage rots in ginger. Pythium aphanidermatumand P. myriotylum associated with rhizome rot ofginger in India has been reported by many workers(Uppal, 1940; Shahare and Asthana, 1962;Bharadwaj et aI, 1988). Involvement of Pythiumspp. and Fusarium spp. in storage and field rotshas been reported (Dohroo and Sharma, 1983).

From the present study, it was inferred thatthe individual fungal and bacterial pathogenscaused maximum disease and combination ofpathogens did not increase the disease incidence.The nematode did not cause wilting, but it couldincrease the disease incidence caused by thefungal pathogens. Maximum rhizome rot (75%)was noticed in plants where Pythium sp. appliedalong with F.oxysporum. Maximum number ofplants died, where the plants inoculated withR.solanacearum (90.24%) followed by Pythiumsp. (85.36%). It was also noticed that, whereverR.solanacearum inoculated along with other

Table 1. Relative severity of diseases caused by different pathogens of ginger

Treatments % Rhizome Root RhizomeMortality Rot (%) Rot(%) Yield (g /pot)

Pythium 85.3 73.0 77.0 061.8Fusarium 60.7 13.0 14.0 126.2

R solanacearum 90.2 70.0 71.0 087.5

Pratylenchus 00.0 20.0 20.0 183.1

Pythium + Fus. 78.7 75.0 78.0 063.7Pyth. + R.sol. 64.6 46.0 48.0 130.6

Pyth. + Praty 70.0 34.0 48.0 190.6Fus. + Rsol. 75.9 68.0 63.0 091.2

Fus. + Praty 62.5 50.0 50.0 160.0

Rsol. + Praty 85.96 63.0 80.0 068.7All pathogens 79.16 73.0 81.0 097.5Control 00.00 00.0 01.0 196.2

LSD at 5% 05.3 28.0 30.0 49.3

• Average of eight replications

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pathogens, the death rate was more. From theexperiments with the agro-chemicals, the use ofCOC (Fytolan) on the reduction of diseaseincidences as well as their role in the diseasemanagement was proved.

All the chemical treatments reduced therhizome rot. Copper oxychloride was effective inthe control of root rot and mortality due to different

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pathogens. All other treatments were either lesseffective or ineffective in the control of the diseases.(Table 2).

In general, T. harzianum controlled rhizomerot, root rot and mortality caused by both fungaland bacterial pathogens. However, when thepathogens were applied in combination, efficacy ofT. harzianum in their control varied (Table 3).

Table 2. Efficacy of various chemicals in the control of seed borne infection of pathogens of ginger

Treatments % Rhizome Root RhizomeMortality Rot (%) Rot (%) Yield (g/pot)

25.0 08.1 05.6 113.737.0 08.1 12.5 126.300.0 05.6 00.0 114.4

50.0 08.1 01.3 124.4

12.0 01.3 02.5 116.312.0 02.5 06.9 126.300.0 08.8 12.5 125.000.0 00.0 00.0 151.300.0 03.1 13.8 177.537.0 06.3 00.0 118.837.0 26.9 15.0 083.8

05.6 13.2 00.5 038.1

Ridomil (Matco) 500ppmCarbendazim(Bavistin)Q.2%COC* (Fytolan)0.2%Phorate (Thimat) 15g/potMatco + PhorateBavistin + PhorateCOC + PhorateMat+COC+Bav+PhoHealthy seed + HWInfected seed + HWInfected seed

LSD at 5%

Table 3. Efficacy of Trichoderma harzianum on control of ginger pathogens

Treatments Rhizome Root % of RhizomeRot(%)* Rot (%)* Mortality Yield (g/pot)

SCA + Pyth. 03.0 01.0 00.0 218.8SCA + F.oxy. 04.0 01.0 00.0 202.5SCA + R.sol. 28.0 26.0 25.0 137.5SCA + Praty. 06.0 12.0 00.0 195.0SCA + Pyth. + F.oxy. 61.0 62.0 00.0 098.8BCA + Pyth. + Praty 23.0 23.0 00.0 152.5BeA + F.oxy. + Praty 04.0 01.0 00.0 202.5BeA + R.sol. + Pyth. 45.0 43.0 25.0 101.3BeA + R.sol. + F.oxy. 53.0 55.0 12.5 087.5BeA + R.sol. + Pyth. + F.oxy. 08.0 06.0 12.5 163.8BeA alone 00.0 00.0 00.0 183.8Pythium sp 81.0 77.0 75 ..0 197.5F.oxysporum 27.0 31.0 00.0 075.0R.solanacearum 69.0 71.0 50.0 155.0

LSD at 5% 28.0 33.0 00.9 073.5

* Average of eight replications

• Average of eight replications

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From the above experiments, it has beenproved that Pythium sp., Fusarium sp. and R.solanaceaum are involved in ginger diseases.Further, the role of the different chemicals as wellas the use of Trichoderma harzianum on gingerdisease management in Sikkim has been proved.

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Shyam, K.R (1988). Biological control of rhizomerot of ginger in storage. Indian J. PI. Pathol. 6: 56-58.

Dohroo, N.P. and Sharma, S.L. (1983). Evaluation offungicides for the control of rhizome rot of gingerin storage. Indian Phytopath. 36: 691-693.

Haware, M.P. and Joshi, L.K. (1973). Yellow diseasesof ginger (Zingiber officinale) from Madhya Pradesh.Indian Phytopath. 26: 754-755.

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Lum Keng, Yeang. (1973). Cross inoculation studiesof Pseudomonas solanacearum from ginger.MARDI. Res. Bull. 1: 15-21

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Teakle, D.S. (1965). Fusarium rhizome rot of ginger inQueensland. Queensland J. Agrl. and Animal Sci.22: 243-272.

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Received for publication July 11, 2001