Naidu, R.Venugopal, M.N.2014-06-132014-06-132007-02-08J.Plantn.Crops 1989 Suppl. v-16 p-267-271http://hdl.handle.net/123456789/2906Monitoring of forty nurseries raised through seed and voluntary seedlings and twenty two plantations situated at 6-9 Km from the source of inoculum revealed that voluntary seedings collected from infected plantations and the nurseries located in the vicinity of diseased crop from the primary foci of disease spread. Entry of disease also occurs in contiguous and nearby plantations up to 1,000 m from the external inooulum source. Further centrifugal influx was recorded around primary foci due to secondary spread by the vector. Spatial pattern of spread is concentrated within 40 m radius with occasional introduction of disease up to 90 m distance. Sharp difference in the pattern of spread was observed between the plots with and without roguing. The gradient of the disease decreases steeply near the source of inoculum and less steeply at great distances.enArticle