Resistance to rust (Puminia arachidis Speg.) and late leafspot (Cercospridium personaturn (Berk. & Curt.) Deighton) in some peanut genotypes was studied under field conditions. Late leafspot development was also assessed in the glasshbuse and the parameters lesion diameter, defoliation percentage and sporulation gave highly significant correlations with the field disease scores. Several genotypes were found to be resistant to both rust and late leafspot and should be useful sources of multiple diseaseresistance in a breeding program.
Rosette is the most destructive virus disease of groundnut in sub-Saharan Africa. It is caused by a complex of three agents, namely groundnut rosette assistor virus, groundnut rosette virus and its satellite RNA. The disease appears to be indigenous to Africa as it has not been recorded elsewhere. Thus rosette represents a newencounter situation as the disease is thought to have spread to the introduced groundnut from indigenous host plants. Rosette has been known since 1907 and much information has been obtained on the main features of the disease, viz. its biology, transmission, viral aetiology and diagnosis, and the impact of chemical control of the aphid vector, cultural practices and virus-resistant varieties on disease management. However, there are still many gaps in the available knowledge, especially the reasons for the large and unpredictable fluctuations in the incidence and severity of rosette disease throughout sub-Saharan Africa. Three unresolved issues of particular importance concern the nature of the primary source(s) of inoculum, the means of survival of virus and vector during unfavourable periods, and the distances over which the aphid vector can disperse and disseminate virus. Now that the aetiology of the disease is understood and diagnostic tools have been developed, the time is opportune for new initiatives in understanding the ecology and epidemiology of rosette. Substantial progress can be made by developing a co-ordinated multi-disciplinary research programme and making full use of the latest techniques, approaches and experience gained elsewhere with other insect-borne viruses. This information would help to explain the sporadic disease epidemics that cause serious crop losses and sometimes total crop failure, and would also facilitate the development of disease forecasting methods and sustainable integrated disease management strategies. Davies J C. 1972. Studies on the ecology of Aphis criicci\ww Koch (Hem., Aphididae). the vector of rosette disease of groundnuts. in Uganda. Birllrtiii of Eritoriinlagii.tr1 ReseciriA 62: 169-1 8 1. Davies J C. 197%. Insecticides for the control of the spread of groundnut rosette disease in Uganda. PANS 21: 1-7. Davies J C. 197%. Use of Menazon insecticide for control of rosette disease of groundnuts in Uganda. Tropical Agric~tltitre. Triiiiil~iil 52:359-367. Davies J C. 1976. The incidence of rosette disease in groundnut in relation to plant density and its effects on yield. Anrials of Applied Biology 82:489-501. Davies J C, Kasule F K. 1964. The control of groundnut rosette disease in Uganda. Tropicril Agriculticre. Trinidrd 41 303-309. de Berchoux C. 1960. La rosette de I'arachide en Haute-Volta. Comportenient des lignees resistantes OlPagirieux 15229-233. Demler S A, Rucker D G, de Zoeten G A, Ziegler A, Robinson D J, Murant A F. 1996. The satellite RNAs associated with the groundnut rosette disease complex and pea enation mosaic virus: sequence similarities and ability of each other's helper virus to support their replication. Jourriiil of' Gerie...
7'hcc~ulti~utedpc~a,r1~/ (Arachis hypogaea. Fubaccac) is belic~ved to have orlginutcjd ulorrg I/?(, C~U S I C~I I slo/)c,s (?f ihr ..lnrl(s in Bo111.ia und northerr1 Argentina. The crop 1s t~orc groLt,tr thronghout i r o~~i c~u l utid warm tonpiJralr regron.c. .4rnong diseases uttac.krn,q pc,ut~lrrs, rlitr cwlr.,c~/ hjl Puccinia arachidis arid larr, Ieuf'spot cuuscd hj, Phaeoisariopsis personata urea flic r?io.sl rt?iportan/ and dcstrurttvc~ on a ~, o r l d~, i d r .\c,olc. noti? pa//iogc,tr~, rr,stric./cd rn host run@, to Arachis, prohahly originated and c,oc,vol\,ed irl .Siiut/r .,ltnrriiu alclt~y ~i'ith thrir /~ost.s. In rcwnr years there has heen 1?11i(./r ~rtlphusr.\
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