Ergot is a serious endemic disease in most of the sorghum (Sorghum bicolor) producing countries of the wor ld, wi th most recent outbreaks being in central and South Amer ica (Reis et al . 1996). It is caused by the fungus Claviceps spp. Three species are predominant: C. africana is prevalent in southern and eastern Af r ica, South Amer ica, Southeast Asia, Aust ral ia, and India; C. sorghi in India and Southeast Asia; and C. sorghicola in Japa

Navi, Shrishail

Thein, Moung

Tonapi, V.

Tooley, P.

Vinh, Dang

Wirojwattanakul, Komin

English

Ergot is a serious endemic disease in most of the sorghum (Sorghum bicolor) producing countries of the wor ld, wi th most recent outbreaks being in central and South Amer ica (Reis et al . 1996). It is caused by the fungus Claviceps spp. Three species are predominant: C. africana is prevalent in southern and eastern Af r ica, South Amer ica, Southeast Asia, Aust ral ia, and India; C. sorghi in India and Southeast Asia; and C. sorghicola in JapanThis article is from International Sorghum and Millets Newsletter, 44 (2003): 95–97.</p

Digital Repository @ Iowa State University (ISU)

Prevalence of Sorghum Ergot in Southeast Asia

Ergot is a serious endemic disease in most of the sorghum

(Sorghum bicolor) producing countries of the wor ld, wi th

most recent outbreaks being in central and South

Amer ica (Reis et al . 1996). It is caused by the fungus

Claviceps spp. Three species are predominant : C. africana

is prevalent in southern and eastern Af r ica, South

Amer ica, Southeast Asia, Aust ral ia, and India; C. sorghi

in India and Southeast Asia; and C. sorghicola in Japan

Tonapi, V A

Wirojwattanakul, K

Vinh, D V

Thein, M M

Navi, S S

Tooley, P W

ICRISAT Open Access Repository

prevalence of C. sorghi as a predominant species in thisregion. The type 4 sclerotia observed here suggest thecoexistence of C. sorghi and C. africana in India.Based on a comparat ive study of C. sorghi and C.africana, Frederickson et al . (1991) and Bandyopadhyayet al . (1998) indicated that the abi l i ty of C. africana inproducing secondary conidia may be considered as a di f ferent iat ing character of this species. Subsequently,occurrence of C. africana in India was reported by Bogoand Mant le (1999). Further, Pazoutova et al. (2000)reported that C. africana has a greater epidemiologicaladvantage, ie, dispersal ef f ic iency, than C. sorghi as itproduces secondary conidia in v ivo . However, in thisstudy, profuse product ion of secondary conidia was alsoobserved in C. sorghi. Therefore, the product ion ofsecondary conidia may not be considered as a di f ferent iat ingcharacter of the two species. Pazoutova and Bogo (2001)have concluded that C. sorghi is present in Central Indiaas a minor pathogen. However, in this study, only one ofthe 74 isolates resembled C. africana and the remaining73 were morphologica l ly s imi lar to C. sorghi indicat ingthat it is a major pathogen in South India. Thus C. sorghi has retained its or ig inal niche wi thout replacement byC. africana It is necessary to conduct further studies onC. sorghi and to better understand its diversi ty anddistr ibut ion.ReferencesBandyopadhyay R, Frederickson DE, McLaren NW,Odvody GN and Ryley MJ . 1998. Ergot: a new disease threatto sorghum in the Americas and Australia. Plant Disease82(4):356-367.Bogo A and Mantle PG. 1999. Claviceps africana discoveredin India. Plant Disease 83:79.Frederickson DE, Mantle PG and deMilliano WAJ. 1991.Claviceps africana sp. nov., the distinctive ergot pathogen ofsorghum in Africa. Mycological Research 95(9): 1101-1107.Frederickson DE, Odvody GN and Isakeit T. 1999. Sorghumergot distinguishing sphacelia and sclerotia of Claviceps africana in seed. Texas, USA: Texas Agricultural ExtensionService, Texas A & M University.Pazoutova S, Bandyopadhyay R, Frederickson DE, MantlePG and Frederiksen RA. 2000. Relation among sorghumergot isolates from the Americas, Africa. India and Australia.Plant Disease 84:437-442.Pazoutova S and Bogo A. 2001. Rediscovery of Claviceps sorghi (Ascomycotina: Clavicipitaceae) in India. Mycopathologia153:99-101.Rajasab A H . 1980. Aerobiological investigations on somediseases of sorghum. PhD thesis, Mysore University, Mysore,India. 228 pp.Ramaswamy C. 1968. Meteorological factors associated withthe ergot epidemic of hajra (Pennisetum) in India during thekharif season, 1967 - A preliminary study. Current Science37:331-335.Sangitrao CS. 1982. Studies on sorghum ergot in Vidarbharegion. PhD thesis, Dr Panjabrao Deshmukh KrishiVidyapeeth. Akola, Maharashtra, India. 208 pp.Tsukiboshi T, Shimanuki T and Uematsu T. 1999. Claviceps sorghicola sp. nov., a destructive ergot pathogen of sorghum inJapan. Mycological Research 103(11)1403-1408.Prevalence of Sorghum Ergot inSoutheast AsiaVA Tonapi1,2*, Komin Wirojwattanakul3, Dang VanVinh4, Moung Moung Thein5, SS Navi1,6 andPW Tooley7 (1 . ICRISAT, Patancheru, 502 324, AndhraPradesh, India; 2. Present address: National ResearchCentre for Sorghum, Rajendranagar, Hyderabad 500 030,Andhra Pradesh, India; 3. Division of Plant Pathologyand Microbiology, Department of Agriculture, Chatujak,Bangkhen, Bangkok 10900, Thailand; 4. Wheat ResearchDepartment, Vietnam Agricultural Science Institute(VASI), Thanh Tri, Hanoi, Vietnam; 5. Department ofPlant Pathology, Central Agricultural Research Institute(CARD, Yezin-Pyinmana, Myanmar; 6. Present address:Department of Plant Pathology, College of Agriculture,Iowa State University, Ames, Iowa 50011-1020, USA;7. USDA-ARS, 1301 Ditto Avenue, Fort Detrick, MD21702, USA)*Correspondig author: vilastonapi@hotmail.comIntroductionErgot is a serious endemic disease in most of the sorghum(Sorghum bicolor) producing countries of the wor ld , w i thmost recent outbreaks being in central and SouthAmer ica (Reis et al. 1996). It is caused by the fungusClaviceps spp. Three species are predominant: C. africana is prevalent in southern and eastern A f r i ca , SouthAmer ica , Southeast Asia, Austral ia, and India; C. sorghi in India and Southeast As ia ; and C. sorghicola in Japan.Ergot can cause widespread damage of male-fert i lecultivars in farmers' fields when environmental condit ionsfavorable to the pathogen occur at f lower ing (Mole fe1975, Kukedia et al. 1982, Nav i et a l . 2002). In addi t ion,ergot has great potential to damage sorghum nurseriesand cause signif icant damage to hybr id seed product ion.Losses f rom ergot have been estimated at 1 0 - 8 0 % inIndia and South A f r i ca and 10 -100% in Braz i l(Bandyopadhyay et al. 1996). In this art icle, we reportI S M N 44 ,2003 9 5prevalence and dist r ibut ion of ergot pathogens indif ferent geographic regions of V ie tnam, Thai land andMyanmar.Materials and MethodsLocations surveyed. The object ive of the survey inSoutheast Asia was to understand the diversi ty insorghum ergot pathogen and prevalence of di f ferentspecies as was done in India by Bandyopadhyay et al .(2002). The disease was ident i f ied using theident i f icat ion keys of Frederiksen and Odvody (2000).Incidence and severity f r om each sorghum f ie ld wasrecorded f rom an area of approximately 12 m2 at threespots selected at random. Disease incidence (%) wasrecorded based on number of plants infected out of thetotal plants counted, and the severity was recorded on0 - 1 0 0 % based on f loral infect ion (%) in ind iv idualpanicles ( 0% = healthy and 100% = entire panicle infected).Extensive on- farm disease surveys were conductedbetween August and November 2002 in V ie tnam,Thai land and Myanmar . We surveyed 21 farms in twoprovinces (Sonla and Nghean) in V ie tnam; 178 farms in 7 provinces (Nakhon sawan, Lopbur i , Saraburi,Kanchanaburi, Nakhonratchasima, Sa Keo and Suphanburi)in Thai land; and 87 farms in 10 townships (Taktone,Nyaungoo, Onetwine, Nwahtogy, Nyangoo, Tuangtha,M o n y w a , Chuangoo, Yezagyo and Kyaukpadaung) inMyanmar.Ergot prevalence and sampling. A total of 24 ergotsamples were col lected dur ing the survey (Table 1); ofthese, two were f rom V ie tnam, 18 f r om Thai land, andfour f rom Myanmar . The samples were placed separatelyin b rown paper bags, air-dr ied and stored at laboratorycondit ions (25±1°C) for further studies at the Uni tedStates Department of Agr icu l ture ( U S D A ) laboratory ofDr Paul Tooley at Fort Det r ick , Mary land , U S A for theircul tural characteristics and their genetic diversi ty.Pathogenicity test of samples collected in Tha i land.Conid ia l suspensions of the ergot samples col lected inThai land were spray-inoculated separately using conidia lspore suspension at the concentrat ion adjusted to 1 x 106conidia ml-1 (Tonapi et a l . 2002) on to sorghum cul t ivar296A at st igma emergence stage. The study wasconducted under contro l led environment at the D iv i s ionof Plant Pathology and M ic rob io logy , Department ofAgr icu l tu re , Bangkok, Thai land. The inoculated panicleswere covered w i t h b rown paper bags and incubated for3-5 days at 25±1°C. Further, the plants were incubatedunder greenhouse condit ions (25±1°C) for diseasedevelopment. F rom the infected panicles, 5 - 6 infectedspikelets were col lected in steri l ized paper bags anddispatched to the Foreign Diseases and Weed ScienceResearch Inst i tute, U S D A , Fort Detr ick,Cropping PatternSorghum is a minor crop in V ie tnam and is g rown in verysmall areas in remote h i l l y regions main ly for fodder.Table 1. Prevalence of sorghum ergot in Southeast Asia.No. of No. of Disease Disease No. ofProvince/District/ fields fields incidence severity samplesDivision/Township Village surveyed with ergot (%) (%) collectedVietnam 21 2Mochau Hangchang Traces 2-7 2Thailand 178 18Lopburi, Moung Nikhom 8-10 2-60 2Lopburi, Moung Khoktoom Traces 2-10 3Lopburi, Pathanikhom Delang 2-5 5-15 1Lopburi, Moung Khoukeinlai Traces 2-15 2Nakhon sawan, Moung Nongpring Traces 10-40Saraburi, Wang moung Manavan 10-30 50-90Saraburi, Wang moung Namsuk 5-20 30-70Saraburi, Paphuthabat Saraburi 2-15 20-100Kanchanaburi, Dhamakantiya Dhamakantiya Traces 10-100Sa Keo, Wangnamyen Sa Keo 20-60 80-100Saraburi, Wang moung Wang moung 5-20 60-100Suphanburi, Uthong Suphanburi 15-80 45-100Myanmar 87 4Onetwine, Mandalay Shawbin 2-40 10-80 2Onetwine, Mandalay Beckone Traces 5-40 1Onetwine, Mandalay Oktwin 2-15 20-80 196 I S M N 44, 2003The sorghum genotypes were ta l l , w i th sweet stalk, redgrains, and take >150 days to mature. In Thai land, hybr idsorghums are predominant over varieties and foragetypes. In Myanmar , sorghum is g rown for food as we l l asfor fodder. Sorghum varieties in Myanmar were simi larto those of Thai land and V ie tnam. Dur ing the survey thecrop was in various growth stages f r om vegetative tophysio logical matur i ty or harvestable matur i ty stages.Prevalence of Ergot in Farmers ' FieldsThe most obvious external symptom of ergot observed onpanicles (on nodal t i l lers or on the main plant) was thehoneydew exudation f rom the infected f lowers.Honeydew was either un i fo rmly ye l l ow-b rown to p ink orsuperf ic ial ly du l l whi te. However , no sclerotial stagesymptoms were observed.In V ie tnam, ergot incidence was in traces w i th a severity f rom 2 to 7%. In Thai land, disease incidenceranged f rom traces to 8 0 % and severity f r om 2 to 100%whi le in Myanmar, disease incidence ranged f rom tracesto 4 0 % and severity f rom 5 to 8 0 % (Table 1). Thesamples f rom Myanmar and Vietnam appear to be C.sorghi. Putative C. africana types were observed only inthe Thai land samples col lected f r om Saraburi, Manavanand Namsuk vil lages (Saraburi province) and Suphanburi(Suphanburi province). Claviceps sorghi was alsoobserved in some samples f rom Thai land. Reproductivepotential of ergot pathogen(s) is an importantdetermining factor, wh ich decides the relativepredominance of one species, over the other. Resultsf rom molecular analysis are awaited to dist inguishspecies or var iabi l i ty w i th in the species.Acknowledgment. This research project was funded byU S D A , USA. The views expressed are not necessarilythose of U S D A . The cooperation of farmers, non-government organizations (NGOs) , staff of agriculturaluniversit ies, research stations, v i l lage counci ls andDepartment of Agr icu l ture in V ietnam, Thai land andMyanmar is acknowledged. We thank Suresh Pande,I C R I S A T , Patancheru, India and R Bandyopadhyay,I I T A , Niger ia for their guidance and help dur ing thissurvey.ReferencesBandyopadhyay R, Frederickson DE, McLaren NW andOdvody G N . 1996. Ergot - a global threat to sorghum.International Sorghum and Millets Newsletter 37:1-32.Bandyopadhyay R, Muthusubramanian V, Tooley PW,Chakraborty S, Pazoutova S and Navi SS. 2003. Distributionand diversity of the sorghum sugary disease pathogens in India.Pages 75-79 in Sorghum and millets diseases (Leslie JF, ed.).Ames, Iowa, USA: Iowa State University Press.Frederiksen RA and Odvody GN. 2000. Compendium ofsorghum diseases. Second edition. St. Paul, Minnesota, USA:American Phytopathological Society.Kukedia M V , Desai KB, Desai MS, Patel RH and RajaKRV. 1982. Natural screening of advanced sorghum varietiesto sugary disease. Sorghum Newsletter 25:117.Molefe TL . 1975. Occurrence of ergot on sorghum inBotswana. Plant Disease Reporter 59:751-753Navi SS, Bandyopadhyay R, Nageswara Rao TG andTooley PW. 2002. An outbreak of sorghum ergot in parts ofAndhra Pradesh, India. International Sorghum and MilletsNewsletter 43:68-70.Reis E M , Mantle PG and Hassan HAG. 1996. First report inthe Americas of sorghum ergot disease caused by a pathogendiagnosed as Claviceps africana. Plant Disease 80:463.Tonapi V, Ryley M, Vic Galea, Bhuiyan S and Wearing A.2002. Influence of temperature and relative humidity on pollentraits and ergot severity in sorghum. International Sorghumand Millets Newsletter 43:74-76.Simple Techniques for Productionof Secondary Conidia and ErgotInoculation in SorghumVA Tonapi1,*, MJ Ryley2, V Galea3, S Bhuiyan3 andA Wearing3 (1. ICRISAT, Patancheru 502 324, AndhraPradesh, India; Present address: National Research Centrefor Sorghum, Rajendranagar. Hyderabad 500 030, AndhraPradesh, India; 2. Agency for Food and Fibre Sciences,Department of Primary Industries, PO Box 102, T o o w m b a ,Queensland 4350, Australia; 3. School of Agriculture andHorticulture, University of Queensland, Gatton, Queesnald4343, Australia)*Corresponding author: vilastonapi@hotmail.comIntroductionErgot (sugary disease), caused by several species ofClaviceps inc lud ing C. africana, is a serious panicledisease in most of the sorghum (Sorghum hicolor) producing countries of the wor ld (Bandyopadhyay et al.1998). A i rborne secondary conidia are the pr imarysource of inoculum of C. africana (Bandyopadhyay et al.1998) and are responsible for the rapid spread of thepathogen (Frederickson et al. 1989,1991,1993). Secondaryconidia are produced on sterigmata f rom germinatedmacroconidia f rom the honeydew. To date, al l infect ionstudies have been conducted w i th mixed suspensions ofmacroconidia and secondary conidia, sprayed ontostigmas. However, in nature this does not occur, as theI S M N 44 , 2003 97

Prevalence of sorghum ergot in southeast Asia

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Prevalence of Sorghum Ergot in Southeast Asia

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