Groundnut Ruct Disease: Epidemiology and Control 1 U# P

Groundnut Ruct Disease: Epidemiology and Control 1 U# P. Subrahmanyaml and D. McDonald2

Abstract

Kesearrh on rust dueasc qfgroundnut at ICRIS.4 TCcnterfrorn l!j:h to 198.i is br~e/'l,.. . rc.l,irrc,c~c/. Sprcori of the d~seawin Indin is documented, and the role of conlinuous cultrr~arionqfgroundrrtrt in pcrpetuntinp the disccr\e crnphasi:ed. Daa on ?.ic>ldlosscj frorn ri~stcur prrsc*ri/rtl. .Ilcthoc!s r!f.,c.rct,ning pc,rnrj~lci~mclrlrl hreedrnp llnes ,for resislnnce to rust nrr deccribed, and the rdt,nrr/ird sor~rceso/' reslstcmcc ore lrsted. Cornponrnts ?/ resistance lo rust und their possible use In greenhouse er~nluntlono/ rust rc,srstnnce tue disrussrd. Thr rcsr~lt~o,frnul~iloration testing r!f rilst-rcsis~antprrrn~~lc~rnlincs arr coni(!rrc(i. Thc rffcr~s drficrrnt agronomrc sJ.slerns on cprphvtotlw of rust are d~scussed.

Hnl~illede I'arachidc3--i.pidi.miologie et 111t1e. I,e( arrtrirrrf~cissen~en rc.rut~lorrchcrchc>t mcr~Pes wr la rollrllc d~ l'nrochide au Centre ICRIS.4 T cntrc 157h el 1981 L 'i.tucie tic In Irroprc8\cron dc la nlalcidre en Indr soul~pelc r6/~de I'e~plo~t(~ioncontinue dt, cette culture dans la propcvnflon dc la mcilntl~r.Lrs donnks sur IPJ ycrfes dc rcndcnlrnt hw6 la rou~~I~~onfprLt~ntPes.Lci desrript~on des mdhotic*stic rr~hlqr dcs rrssources ptntlrqua ct des 1rLptcs de s6lect1on pour la r6.s1srancecst si~rrtc d'unr lrsrc de sources de rtsutance repErPcs Les carort?re~lntervenant dans la rblstance sont exwninfs arm1 que lour utllisatron ' Atentuelle duns les A~cllrruhonsen serre de la r&~stanceiL la rourlle. Les rbultats des essais rnr~lliloccu~xciu rnalhr~clgPnitique rhutant son1 prbentb. Enfin, les e/fets d~sdlffirents systPmes agronomrques sur l'ipiphytre de la rourlle son[ Ptud~b.

The rust disease of groundnut (Arachis h~pogaeaL.) Yield losses from rust are substantial, damage being caused by Puccinio arochidis Spegazzini has particularly severe if the crop is also attacked by the increased in importance in recent years. Prior to two leaf-spot fungi (Cercosporo arochiriicola Hori 1969, the disease was largely confined to South and and Plloeoisariopsis personata (Berk. & Curt.) v. Central America, with occasional outbreaks occurr- Arx). ing in the southernmosl groundnut producing areas Rust epidemics arc regular and se\.ere on suscepti- of the USA. The disease was also recorded in the ble groundnut genotypes at ICKlSAT Center. This USSR (Jaczewski 1910), Mauritius (Stockdale paper briefly reviews research on the disease carried 1914), and the People's Republic of China (Tai out in the Groundnut Pathology Subprogram from 1937), but did not become permanently established 1976 to the present time. in these countries (Bromficld 1971). In recent years groundnut rust has spread to, and became established in, many countries in Asia, Australasia, Ocea- Biology of Groundnut Rust nia, and Africa (Hammons 1977, Subrahrnanyam et al. 1979, and Subrahmanyam and McDonald 1983) The life cycle and taxonomy of P. uruchiilis are (Fig.1). Rust is now of economic importance in described in detail by Hennen et al. (these Proceed- almost all groundnut-growing areas of the world. ings), lnvestipations were carritd out on the biology

I. Pathologisr: and 2. I'rinc~p.~l(;roundnut Pa~holog~+t.Lcgulne~ I'rogram. Interr~al~onalCrop Rebearch Insr~ruteIcir ~heSe~ni-Ar~d Tropic\. Patanchcru. A.P. .(0!!2J. Indla.

ICRISAT (ln~crni~rionalCrops Krsedrch In,t~tu~efor thc Scrnl-Ar~dTropics). 19x7. Groundnu1 rust d~scase:I'rocccdlngc of a I)lscusrlon Group Xlecting. 24-18 Sep 1984. I<'KIS,\T Center. India. I'atancheru, ~\.f'. 502 32.1. In41.i ICKISA I. (('I'405) Table 1. Effects of storage temperature on vinbilitj of urediniospores (from 1982). Percentagcl of urediniosporcs \.iablc Storagc rernp. after storage (days) (O'C) 5 13 28 30 48 60 70 78 99 110 120

I IOOn cporcs per sample F~pureslo nearest uhole number Light intensity (. 1000 LUX) Figure 3. Effect of light intensity on urediniospore germination. Arrow indicates germination percentage of the same spores in dark.

(5000 lux and above) was found to inhibit urediniospore ~errnlnation (Fig.!). Urediniospores on exposed infected crop debris lost viability within 4 weeks under postharvest conditions at ICKISAT Cen~er(Table 1).Pods and seeds from rust-affected crops are commonly surface-contaminated with urediniospores at harvest. Tests on urediniospores taken from surface-contaminated seeds stored at 5 10 I5 20 25 30 35 room temperature showed viability10 decrease from Temperature ("C) an initial 95% to zero after 45 days. Inoculation of Figure 2. Effect of temperature on urediniospore twoday-old seedlings of a rust-susceptible cultivar germination. grown in petridishes showed that urediniospores

Table 2. Viabilit! of urediniospores after \arious periods ofelposure lo weather on infected crop debris(from Subrahma-- - n)nm and hlcDonnld 1982). Pcrcenragcl of urcd~niospores\,iablc Rain! -season crops Poslrainy-season crops - 1976 1977 1976-77 1977-78

120 JJ 0 0

120 L wealth 13 Dec 1976 7 Yo\ 1977 4 Aln!. 1977 2 hlay 1978 1. ~~~~~~~hic~\distribution of Pur&ia arachidis (lop) prior (0 1969 (based On map 16, issued 30 June 1966) and lboltomi in 1983 (based on cOmmOnxealth I'rr~od 10 10 10 ro ,cooca of test 7 Jan 1977 2 L)cc 197i 30 Xfa! 1977 28 May 1978 \~,colopicaI. -. Institute map 160, issued I Apr 1980). RHCi 0714 h b0.7 $3 5 M.7 60.7 1414 h pores could be stored for long periods at low temper- 26.0 46.6 26 9 23.9 Temp. ('C) Max. 26.3 28.0 of P, orarhidi~to determine what factors influenced atures without loss of viability. but that at hi6k 37.6 39.7 and spread. Biological data were h41n. 13 4 19.5 24.9 25.6 its temperatures they lost \liability within 5 days (Tab" needed for the dei,e\opmen[ of 1). Temperatures in the range of 20-2PCWere 0pti 1. IN0 spore, pcr zamplc F~purcslo ncares! uhole number screening methods. Ut,oratoriexperimenfi that uredinios- mum for urediniospore germination (Fig.2) Ligh in Tamil h'adu, Andhra f'radesh, Karnataka, and total of 8000 genotypes werc scrcelled ill the pel.ic)d ould germinate on the surfaces of hgpocotyls and Maharashtra States, probably becau- of extensive 1977-83. ,otyledons but no infection developed. Plants grown and continuous cropping (Subrah ;am et a]. Preliminary screening was done on germplasm n sterilized soil from seeds heavily contaminated 1979). During the disease sumey in Gu~arat0 State in multiplication material in the rainy seasons. Geno- with urediniospores, did not become infected with the 1977 rainy season, rust was not obsened in the types were grown in unreplicated, single-row plots. -us1 discase (Subrahmanyam and McDonald 1982). main groundnut-growing tract (Sourashtra region), Rows of the cultivars TMV 2, and Robut 33-1, There is no record of the occurrence of anycollat- but a survey in the 1978 rainy season sho\r'ed rust to known to be highly susceptible to groundnut rust, ~ralhosts of groundnut rust outside the genus Ara- be present and causingserious damage to groundnut were arranged throughout thegermplasm fields uith chis. The possible occurrence of other hosts was crops throughout the state. Rust is now a well estab- I to every I0 test genotypes. One week before harvest considered, and various crop and weed plants grow- lished and destructive disease of groundnut in all each genot!.pe was scored for the development of ing in or near rust-affected groundnut crops on the major groundnut-growing states in lndia. rust using a 9-point scale in which I = no disease, and ICRISAT farm and in farmers' ficlds were examined 9=50-100% foliage destroyed. Genotypes with for rust. Some were also inoculated with uredinios- scores of 5 or less u,ere selected for adwnced pores in the glasshouse. No infection was recorded Assessment of yield losses screening. on any of the plant spccies examined (Subrahma- Advanced screening was done in both rainy and nyam and McDonald 1982). Rust and leaf-spot diseases normall!, occur together postrainy seasons. Genotypes were grown in repli- and it is difficult to allocate indi\.idual rcsponsibilit!, cated plots. Test plots were separated by single infec- for the resulting losses in crop yteld. During the tor rows of a mixture of the culti\,ars Th/V 2 and 1979, 1980. and 1981 rainy seasons. !,ield losscs were Robuf 37-1 soun I4 da!*s bcforc the test material. stimated by applying se1ectn.e fungicides on a wide Figure I. Groundnut cropping seasons in India. Cultivars T.Zl\' 2 and Kobut 33-1 were also soi4.n on ange of susceptible and resistant genotypes; chloro- O~erlnppingof these seasons helps to perpetuate test plots to monitor disease spread from infector halonil to control both rust and leaf spots, carben- rows. Due to the dry atmosphere, rust development rust disease attack. lazim to control only leaf spots, and tridemorph to rs not usuaiiy high during thc postrain), seasor) at ,ontrol only rust. Loss estimates are presented in ICRISAT Center. Therefore, a field-inoculation rable 3. In general. yield losses ujere less in the P. orochidis is known almost exclusively by its technique was developed. Infector rows sown as esistant than in the susceptible genot!,pes (Subrah- described above were inoculated with a uredinios- uredinial stage. There are a,few records of the occur- nanyam et al. 1984). rence of the telial stage on cultivated groundnut pore suspension at the time of peak flowering. The (Fig.+a) and on wild Arachis species (Hennen et suspension (50000-100000 spores ml-1) was made up in tap water to which a small amount of the a\.-these Proceedings). Only the uredinial stage Resistance to groundnut rust (Fig.4(b)) of the rust has been found despite constant wetting agent Tu,een 80 had been added. lnoculation was done in the evening following furrow irrigation. examination of many groundnut germplasm lines Screening of germplasm and wild Arachis specie? at ICRISAT and of rust- Potted "spreader plants" heavily infested with rust were placed systematically throughout the field to infected groundnut plants from various parts of Screening of the world collection of groundnut India. Attempts to induce telial formation by modi- serve as additional sources of inoculum (Fig.6). Fol- germplasm for resistance to rust u,as started at lowing inoculation, the fields u8ere irrigated using fication of environmental factors failed. It was con- ICRISAT Center in the 1977 rainy season, and a cluded that urediniospores were the main, if not the o\,erhead sprtnklers. on alternate days initially, and only, means of rust carry-over and dissernination in rhen as rrqgired b!.climatic conditions until harvest. India. The practice of continuous cultivation of The genot!,pes were scored for rust development groundnut in southern lndia(Fig.5)appears to be an just before hawest using the %point scale. Geno- Table 3. l'ield losses from rust and leaf spot\, ICRISAT important factor in the perpetuation of groundnut t!,pes found resistant to rust at ICRISAT Center are Center, rain! scnsons, 1979. 1980. and 1911. rust in the country (Subrahmanyam and McDonald listed in Table 4, together with their mean rust scores 1982, 1983). Percentage pod-y~eld10,s~ on the 9-point scale. Some of these genotypes are also resistant lo late leaf spot disease (Subrahma- 1-caf Rust and nyam ct al. 1980 a. 1980 b, 1982, and 1983 a). It is Genotjye K uct spo~s Icsf $pots Survey of groundnut rust in India interesting that most of the rust-resistant genotypes Robut 33-1' 57 .5 .5 68 listed in Table 4 originated in Peru, which is beliebed TMV 23 40 3 7 5 8 to be one of the secondary "gene centers" of culti- From 197 1 to 198 1 surveys were made in all major PI 259747' 3 I 2 7 29 groundnut-growing states in lndia to obtain lnfor- \,ated groundnut (Gregory et al. 1980, Ramanatha EC 76416(29?)' I? 10 17 Rao-these Proceedtnps). mation on rust and other diseases ofgroundnut,and NC Ac 17090' 4 I3 26 to assess their relative importance in different Pod and haulm yields, and shellingpercentagesof I. Mean of 1979. 1980. and 1981 rain!-sca\on flrld trials regions. Rust and late leaf spot werc the most corn- all resistan1 genotypes wre estimated in almost all 2. Standard susccpt~blccultirars. the seasons; results of the 1982;83 postrainy and Figure 4. (a) Tcliospores (x 800) and (b) Uredinio- rnon and severe diseases in all major groundnu- 3. Resr.r~antgrnnr!pcs growing areas of India. Rust was particularly serious 1983 rainy-season trials are presented in Table 5 spores (x 800) of Puccinia arachidir.

generations were grown in the field and screened for Table 5. Conrrnued. Table 6. The FESR (Federal Experiment Research Sta- tion Puerto Rico) breedinp, lines rust resistance using the "infector-row"rnethod. The 1982 87 postrain! sawn' leaf spot at ICRISAT Center. populations were classified as resistant (2 and 3 on Yield (kg hir-I) - the 9-point scale), moderately resistant (43, and 6 on Yleid (kg ha-') Shclling Shelling Dixase scores' the 9-point scale), and susceptible (7,8 and 9 on the Pods Haulma (?;,I Pods Haulms (5) Genot!.pe Genotype HUSI I~teleaf spot 9-point scale). Selected lines were advanced by pedi- 190 1 68.3 NC Ac 17142 4299 7475 64.5 1252 TMV Z1 9.0 9.0 gree and bulk pcdigree methods on the basis of yield 4225 86 14 5 1.3 17.22 1803 63.3 and disease reaction (Subrahmanyarn et al. 1985, PI 393646 2543 65.3 FESR 5-P2-Bl 2.0 3 .O PI 259747 421 I 8497 57.2 I333 FESR 5-PI7-BI 2.0 3.0 Reddy et al.-these Proceedings). FESR 7-P13-Bl 2.0 3 .O NC Ac 17506 FESR 9-P3-8, 2.0 3 .O USA 63 Screening of wild ArarJ1i.r species PI 405132 FESR 9-P4-Bl 2.0 4.3 EC 76446(292) FESR 9-P7-8, 2.7 3.3 NC Ac 17090 FESR 9-1'7-B1 2.7 4.3 Sixty-one accessions of wlld species, representing FESR 9-P8-R2 2.0 3.0 five sections ofthe genus Arachis, were evaluated for NC Ac 17132 FESR 9-P12-Bl 2.0 2.7 reaction to rust during the 1980 and 1981 rainy PI 350680 seasons at ICKISAT Center. They were furth~: PI 341879 FESK I I-PI I-B, 2.3 2.7 C.Ko.45-23 FESR 1 2-P4-El 2.0 3.0 tested in the laboratory by inoculation of rooted XC Ac 17133-RI' FESR I?-PS-HI 2.0 2.7 detached leaves (Fip.7). hlos! of he specics werc

FtSK 12-1'6-H, -.17 , 2.1q - immune. 6 were highly resistant, and 2 were suscepti- PI 393526 FESR 12-P14-Rl 2.0 3.3 ble (Subrahmanyam et at. 1983 d). The reactions of PI 393516 FESR 13-PI2-El 2.0 2.7 selected u,iId Aracht.~species to rust disease are pres- Krap.st.16 - ented in l'able 7. NC Ac 927 i. On a 9-point scale, u hcrc I - nod~cea\e,and 9 = 50-IWi follagc RMP 12 destroyed. Several diploid wild Aracl~isspecies resistant to 2 Standard susccpl~blecult~tar. rust andior late leaf spot were crossed with high- PI 390595 yielding but susceptiblegroundnut cultivars,and the PI 381622 resulting sterile or fertile tetraploids were treated RMP 91 P1 215696 with colchicine to produce fertile hexaploids. Fol- together with yields of four disease-susceptible NC Ac 15989 lowing field evaluation of hexaploids for disease Indian cultivars for comparison. Several of the resis- resistance, promising selections were backcrossed PI 414331 tant genotypes outyielded the established Indian cul- with the cultivated groundnut cultivars to produce PI 393641 tivars. In addition to the sources of rust resistance NC Ac 17129 listed in Table 4, several other sources of resistance NC Ac 17127 to both rust and late leaf spot diseases have been PI 414332 found in breeding lines from the Federal Experiment Research Station (FESR), Pueno Rico (Table 6). These lines originated from a natural hybrid selected for resistance to rust in Puerto Rico by USDA scientists. Although these lines have low yield poten- tial and poor agronomic characteristics, they are very good sources of resistance to both rust and late leaf spot, and are being used in the breeding program 1948 3.26 at ICRISAT Center (Kigam et al. 1980). cv (yo:,) 9.11' 8.50' 3.19' 17.49 I. Lou disease prcssurc. 2. 1I1gh d~seascprcssurc. Screening of breeding populations 3. S~andardhigh-ylciding chcck cult~tars. 4. Standard error of means for cntrlcl appcxm"n Ihc same block. 5. Standard error of mcans fnr cntrlcs not appcdring In the same block. Several of the sources of rust resistance listed in 6. Efficiency of la~~iccover RBI) IS IOO.LI5C. Tables 4 and 6 haw been extensi\,ely used in the 7. Efficiency of latticc owr RRD is 103.53%. breeding program at ICRISAT Center, and crossed 8. Ffficicncy of lalricc o\cr RRL) IS 112.2%. with high-yielding but susceptible cultivars (Nigam Figure 7. Susceptible groundnut cultivar TMV 2 et al. 1980, Reddy et at. 1984). The F, hybrid plants (left) compared with (right) wild Arachis sp with were normally grown in the greenhouse. Subsequent immunity to groundnut rust. 'Table 7. Reaction of some wild Arochi~species to Puccinia arachidis (from Subrahman!am et PI. 1983 d). USD.4 plant lCRlSAT groundnut Section, series ~n\entory accession 7~ust and spec~es (PI) number number (ICG) reaction Section: Ararhis

Series: Annuor A. bari:ocoi 8124 Immune A, duranrnsis 8123 Immune A. .spr~a::inii 8138 Immune

Series: Perennes .A. (orrcnrrno Immune A. s~rr~u.\pi,rt?io ll ighly resistant A, rordenosii lmmune A. C/IU~'OPIISC Immune A. i.i/loso lmniunc Figure 8. Scanning electron micrographs (x 400) of pustules of Puccinia arachidis on (a)the susceptible cultivnr TMV 2 and (b) on the resistant genotype NC Ac 17090.

Series Tr.rro/oiialr A. opprcssiprloi .A, poru~uarii~n.ris' Tnhle 8. Components of resistance to rust in groundnut genotypes (after Subrnhmanyam et al. 1983b, 1983~). Rust Incubation lnfcction I'ustule Pustules Spores Urediniosporc 5131 lmmunc field period frequency diameter ruptured mm-2 pustule germination Genotype score1 (days) (lesions cm-2) (mm) (%) area (%I Section: E.vrroner\~o~ae TMV 2 (Check) 9.0 9.3 13.5 1.12 100.0 855 75.1 A. \~illosulirorpa1 8142 Immune NC Ac 17090 2.2 ' 19.3 5.9 0.68 0.5 12 1 37.2 EC 76446(292) 2.8 17.5 6.2 0.59 13.5 6 1 48.1 Section: Rhi:oma~osae PI 405132 2.4 18.3 8.1 0.63 5.6 127 48.1 Series: Eurhi:onia~osoe PI 407454 2.8 18.5 4.7 0.58 4.7 139 42.6 A, hagenhrckii 338305 8922 Immune PI 393643 3.O 14.7 5.5 0.73 9.2 12 1 43.3 A. glahrara 338261 8 149 lmmune I. Mean rust scores recorded at the ICRlSAT Center over the years 1979-82. using a 9-point disease scale, where I = no disease, and ! So PI number allocated because the source ma5 not the USDA. . 9 2 50.100% lollage datroyed.

breeders' lines with 40 chromosomes. These tetra- fungus died shortly after entering the substornatal greenhouse, but classification of moderately resis- ploid. or near-tetraploid, lines were evaluated in cal-ity (Subrahman!fam et al. 1980 b). Differences in tant genotypes in this way was less effective than by Table 9. Rust reactions of lour groundnul genot!pn 30 field-screening trials for rust and late-itaf spot resis- resistarm sere associated with differences in rate use of field scores (Subrahrnanyam et al. 1983b). days after inoculation at three physiological stages of tance, using the "infector-row" method. and several and extent of rnycelial development within the cavity development in the greenhouse(after Subrahmnnyam et al. The extent of rust damage to foliage is dependent lines with rust resistance and high yield were selected and w,ithin leaf tissues. The rust resistanceat present 1980). on the physiological age of the plant. Young plants (Singh et a1.-these Proceedings). available in the cultivated groundnut is of the "slow Percent leaf area damaged by rust rusting" type i.e., resistant genotypes have increased are most susceptible to rust attack and the suscepti- incubation period, decreased infection frequency, bility declines with age (Table 9) (Subrahmanyam et Plant stage at inoculation al. 1980a). Components of rust resistance and reduced pustule size, spore production (Fig.8), Peak Nearing and spore gcrminability (Tahlc 8) (Subrahmanyam -Genotype Seedling flowering maturity In studies of components of resistance to groundnut et al. 1983 b, 1983 c). TMV 2' , 100.0 85.5 41.1 The possible use of the resistance components in Stability of rust resistance rust, it was found that neither the size nor the fre- SC Ac 17090' 4.0 6.5 2.8 quency of stomata were correlated u.ith resistance. greenhouse screening of germplasm has been stu- The International Groundnut Foliar Diseases NC Ac 171291 26.7 38.1 5.9 Urediniospores germinated on leaf surfaces and the died. All the components were significantly corre- PI 2597471 Nursery (IGFDN),a cooperative international pro- 50.1 30.8 2.9 fungus entered through stomata irrespective of lated with mean field rust scores. Resistant and gram, was initiated in 1980. Through the assistance I. Culuvar susceptible lo rust. whether a genotype was immune, resistant or sus- susceptible genotypes were readily separated on the of cooperators in locations throughout the SAT, the 2. Cultivar resistant to rust. ceptible to rust. However, in in~muncgcnot!rpes the basis of resistance components measured in the [ion ilr pcrrrntagc leaf area damaged lrom isafbpota tGFDN aims to check under a range of cnrlron- Table 10. Effect of the h!perpurnsite J'erticillium kcani Sul)rmt~~nan)u~~~,P., Iimn~n~onr. W.O., Sigmtti, S.S., mer\ts the stability of resistance to rust and late on groundnut developme between sole and iniercrop systems, but the percen- hlcDunald, D., Gibbons, R.W., Fnn,M.Y.,and Ych,IV.L. leaf-spot diseases of genotypes identified as resistant tage leaf area damaged from rust u wer in the 1983a. International cooperative screening for resistance of to these diseases at ICRlSAT Center. A collection intercrop situation. peanut to rust and late leaf spot. Plant Disease 67:1108- assessed by measuring of 43 resistant and susceptible genotypes identified Investigations on the effccts of blending rust and 1111. andlor assembled at ICRISATW~Sincluded in the infection Leaf late leaf-spot resistant and susceptible genotypes on Subrahmanynm, P., and McDonald, D. 1982. Groundnut nursery. At present, the nurseries have been located Inoculation frequency area the development of these diseases, and on yields rust - its survival and carry-oi,er in India. Proceedings of (lesions cm-2) damaged (%,) in 8 countries in Asia, l I in Africa, and 3 in the treatment were carried out during the 1981-82 postrainy, 1982 the Indian Academy of Scicnccs, Plant Scicnccs 91;93-100. Americas. In India, nurseries were established at 14 Rust pathogen alone 12.6 19.9 rainy, and 1982183 postrainy seasons. Two trials Subrahmanyam, P., and ~i~onald,D. 1983. Rust disease locations through cooperation with the All India were conducted in each season, with two sets of Rust + h1,perparasite of groundnut. (Summary in Fr.) Information Bulletin resistant and susceptible genotjepesphysically mixed Coordinated Research Project on Oilseeds (mixture) 7.3 8.6 no.13. Patancheru, A.P., 502324, India: International (AICORPO). in difierent ratios. In general, the resistant genotypes Crops Research Institute for the Semi-Arid Tropics. Preinoculation uith the grown in mixed crops showed higher percentage The results obtained so far have not been consist- Subrahman)am, P., McDonald, L)., Gibbons, H.W., hj pcrpamslte 5.3 7 4 defoliation than those grown as pure crops. There ent and it is not yet possible to conclude if the rust Nigam, S.N., and Scvill, D.J. 1982. Resistance to rust and resistance identified at ICRISAT is stable or not. In were no significant yield advantages from blending late leaf spot diseases in some genotypes of Arachis hyo- many locations the entries wcre only e1,aluated resistant and suscrptible genotypes. gut2u. Peanut Scirncr Y:6-10. under IOU' disease pressure. Howcver. useful data Suhrahmanjarl~,P., >lrDonnld, I)., Gibbons, H.\V.,and have been obtained from a few locations. It is inter- Rao, P.V.S. 1983b. Cornpollrnts of resistance to Plcc,citiiu esting that the entry NC Ac 17090, which is highly uruclucl,~.Ph!,topathology 73:?53-256. resistant to rust at lCRlSAT Center, \\,as found to Subrnhnian~nrn, P., hlcDonnld, D., and Hao, P.V.S. be only moderately resistant in the People's Repub- caricis (Fr.) 0. Ericks, and Acrer?~oniuntpersi~inurn References 1983~.Influence of host genotype an uredospore produc- China and susceptible in Taiwan. In contrast, (Nicot). if'.Gams have been found growing on P. lic of tion and gcrminabiliry in Puc,cir~iunrarhidis. Phytopathol- oral*ilidisand their pathogencity has been confirmed the entry PI 298 1 15, which is only moderately resis- Bromfield, K.R. 1971. Pcanut rust: a reiio~oi Ilterature. ogy i3:7?6-729. tant to rust at ICRISAT Center. was highly resistant in laboratory inoculation tests. Preliminary investi- Journal, Arncrican Peanut Research and Education Asso- in the People's Republic of China and in Taiwan. gations on the biological control of rust with V. cialion 3:111-121. Subrahmanyam, P., hlehnn, V.K., Ncvill, D.J., and Ieca~~iin the laboratory using detached leaves hIcDonald, D. 1980b. Research on fungal diseases of Rust isolates from many parts of the world are being Gregory, W.C., Krapovikas, A., and Gregory, hl.1'. 1980. showed considerable reduction in rust development groundnut at ICKISAT. l'aprs 193-198 in Procecdlngs of tested for pathogenicity to a range of groundnut Structure, variation, evolution, and classification of Ara- the International Workshop on Groundnuts. 13-17 Oct (Table 10). genotypes by workers in the United Kingdom. chis. Pages 469-481 in Advanccs in legume science. Vol. I. 1980, lCRlSAT Center, India. Patancheru, A.P., 502 324, International Legume Conference, 31 Juld Aug 1978, India: International Crops Research Institute for The Kew, Surrey, UK. (Summerfield, J.. and Bunting, A.H., Serni-Arid Tropics. Biological control of groundnut rust Epiphjtotics of groundnut rust in different eds.). Kew, Surrey, UK: Royal Botanic Gardens. agronomic systems Subrahrnanynm, P., Moss, J.P., and Rao, V.R. 1983d. Hammons, R.O. 1977. Groundnut rust in the United States Resistance to peanut rust in wild Arocllis species. Plant The fungi, Verticillium lecani (Zimmerm.) Viepas and the Caribbean. PANS 23:300-3W. Disease 67:209-2 12. (Fig.9) Penicillium islandicum Sopp., Eudarluca Many small-scale farmer; in the SAT intercrop groundnuts; traditional combinations often involv- Jaczewski, A. 1910. Year book on the diseases of plants, p. Subrahmanyam, P., Rcddy, D.V.R.,(;ibbons, R.W., Rao, 465 (in Russian). (Publisher not known.) ing up to 5 or 6 crops. Although information is V.R., and Gnrren, K.H. 1979. Current distribution of a\.ailable on crop combination, genotype interac- Nigam, S.N., Dwivedi, S.L., and Gibbons, R.W. 1980. groundnut rust in India. PANS 25(1):25-29. tion, proportion of each crop in the intercropping Groundnut breeding at ICKISAT. Pages 6248 in Proceed- Subrahmanynm, P., Reddy, I..J., Gibbons, H.W., and system, land rquivalcnt ratio, etc., very little is ings of the International Workshop on Groundnuts. 13-17 >lcl)onald, D. 1935. f'e;tnut rust: a major threat to peanut known of how intercropping affects foliar diseases at 1980, lCRlSAT Center. India. Patancheru, A.P., production in the semi-arid tropics. Plant Disease 69:813- 1ndia:lnternational Crops Research Institute for the Semi- of groundnut. Trials were carried out at ICRISAT 819. Arid Tropics. Center during the 1980, 198 1, and 1982 rainy seasons Subrnhman)nm, P., \Villiurns, J.H., hlcDonuld, D., and to investigate the effect of intercropping groundnut Heddy, L.J., Nigam, S.S., Submhmanyam, P., Dwivedi, Gibbons, R.W. 1984. The influence of foliar diseases and with cereals on thedevelopmcnt of rust and leaf-spot S.L., Gibbons, R.W., and McDonald, D. 1984. Develop- their control by selective fungicides on a range ofground- diseases. In the 1980 rainy season, there were statisti- ment of foliar diseases resistant groundnut lines at ICRI- nut (Arochis h~pogoeaL.) genotypes. Annals of Applied SAT. Proceedings of American Peanut Research and cally significant differences in percentage defoliation Biology 104:467476. Education Society 16:38. Llobile, Alabama, USA: the and percentage leaf area damaged from rust and leaf Socicty. Tai, F.L. 1937. A l:st of fungi hitherto unknown from spots between sole-crop and intercropspstems. Rust China. Science Reports of the National Tsing tlau Univer- and leaf spot severity was higher on groundnut Stockdale, F.A. 1914. Annual report. Xlauritius: Dcpart- sity, Series R 2:191-639. ment of Agriculture. grown as a sole crop than in intercrop situations. Results obtained from the 1981 rainy season were Subrahmanynrn, P., Gibbons, R.\V., Sigam, S.N., and Figure 9. Urcdinia of Puccinia arachidis parasitized largely in agreement. In the 1982 rainy season there Hao, V.R. 1980a. Screening methods and further sources of resistance to peanut rust. Peanut Science 7:lO-12. by Varticillium Iecani. were no significant differences in percentage defolia-