1978006:

Anthracnose of Sorghum In Brazil

F. T. Fernandes and R. E. Schaffert*

JIn the early seventies, when sorghum began toexpand in Brazil, it was noted that a relativelylarge number of diseases damaged the crop.lnorder to establ ish research priorities in the areaof sorghum pathology, a disease survey wasmade of ali Brazil, using a National DiseaseNursery and other national trials. Foliar an-thracnose was the principal sorghum disease,because of its frequency and intensity in mostareas of the country. Anthracnose damage wasmost intense in Central Brazil. particularly in thearea of Ribeirao Preto, São Paulo. As a result ofthe survey the plant-breeding program at theNational Maizeand Sorghum Research Center(CNPMS) was directed to obtain breeding linesresistant to anthracnose. Selections were madeunder field conditions in Ribeirao Preto and inSete Lagoas, Minas Gerais.

Research at the University of Sao Paulo inPiracicaba aimed at selecting plants resistanttoanthracnose in the greenhouse, is the topic ofseveral thesis problems. As sorghum was a newcrop in Brazil, it was necessary to import ad-vanced breeding materiais to begin the breed-ing programo Many breeding lines introducedfrom Texas A & M University in the USA wereconsidered to be elite with good disease resis-tance, including resistance to the pathoqen Col-letotrichum graminicola (TX-2536, SC-170, SC-173, SC-110, SC-5.99-6-1O,TAM-428, TAM-430).But many of these lines have not shown resis-tance to foliar anthracnose under our condi-tions. These lines were probably evaluated andselected for resistance to red rot (an importantdisease in the USA), and not to foliar anthrac-nose. Other breeding lines, such as TAM-2566,SC-175-14, P-721, TX-623 and TX-399, havebeen highly susceptible under our condrtions.

Actually, the number of lines resistant toanthracnose in our breeding program is small;

* Plant Pathologist, and Sorghum Breeder, CentroNacional de Pesquisa de Milho y Sorgo, EMBRAPA,Sete Lagoas, Brazi!.

they include SC-326-6 and derivatives of SC-326-6, SC-234, SC-239-14, Brandes, and an earlyselection from a late-maturing forage varietyknown as Santa Elisa. In order to increase thislimited genetic base, 400 breeding I ines - in-cluding many sorghum conversion entries-were evaluated last year in Ribeirao Preto andSete Lagoas. Some entries have shown excel-lent levels of resistance and are being evaluatedélgain this year. Unfortunately, last year was dryin central and southern Brazil and the levei ofanthracnose development was below normal.Other material in our germplasm bank is in theprocess of being increased and will beevaluated for anthracnose in the near future.

The pathogen has been identified by its lesiontype and its morphological characteristics (pre-sence of setae. and shape of conid ia) as Col-letotrichum graminicola. However, elongatedlesions have also been encountered, whichcould indicate the existence of other species ofColletotrichum such as C. falcatum.

Anthracnose lesions frequently occur on thepeduncle and stalk, in the panicle, and on thegrain. In the latter case C. graminicola may becontributing to reduced germination and seedl-ing vigor. Tests with seed fungicides are beinginitiated this year.

The inheritance of anthracnose resistance isbeing studied. F1Sand F2Sof crosses betweenresistant lines such as SC-326-6, SC-283, andBrandes I ines, with varying degrees of suscep-tibility such as Wheatland (TX-399), CK-60 (TX-3197), Redlan (TX-378), TX-623, and a male-sterile line BR-007 are being evaluated this year.Preliminary results of last year's workindlcatethat incomplete dominance is involved.

The National Maize and Sorghum ResearchCenter has worked in cooperation with otherinstitutions, principally with Texas A & M Uni-versity in the USA, to study the problems ofanthracnose more closely and would like toexpand these activities.

Our sorghum-breeding program releasodseveral grain-sorghum hybrids, fo~age-

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sorqhurn hybrids, and sweet-sorghum varietieswith.good agronom ic characteristics and excel-lent resistance to diseases during 1978.

Summary

A survey of sorghum diseases in Brazil hasshown anthracnose to be the principal diseaseof this crop because of its frequency and inten-sity. The greatestdamage from this disease hasoccurred in the region of Ribeirao Preto. Selec-tion for resistance to this disease is beingconducted by the National Maizeand SorghumResearch Center, in Sete Lagoas and RibeiraoPreto. Greenhouse studies on resistance arebeing conducted by the University of Sao Pauloat Piracicaba. Breeding stocks imported fromthe USA as sources of anthracnose resistancehave reacted as susceptible to foliar anthrac-nose in our conditions.

The number of resistant lines currentlyutilized in our breeding program is Iimited. Newsources of resistance are being identified fromour germplasm bank and from new introduc-tions.

The pathogen has been identified as Colletot-richum graminicola, though it is possible that C.falcatum could also be involved. Lesions can befound on ali plant parts, incfuding the seed.Preliminary field observations have indicatedthat the inheritance of resistance to this patho-gen is partially dominant.

Commercial grain and forage hybrids andsweet-sorghum varieties resistant to anthrac-nose were released for growing in farmers'fields in 1978.

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