Abstract

India is one of the important groundnut growing countries in the world. Tamilnadu occupies the third place in India as for as groundnut is concerned. Rosette disease of groundnut caused by a virus is gaining importance in India. Sundararaman (1926) first reported the occurrence of the disease at Palur and called it "clump disease". Storey (1935) is of the opinion that natural spread of rosette virus is by the vector Aphis laburni. Storey and Ryland (1955) pointed out the importance of apterous and alate aphids in spreading the disease under field conditions. Rogur Hull (1964) has pointed out the effect of spacing on the primary spread by winged aphids before secondary spread. A thorough knowledge of the source of infection, rate, distance and mode of spread of any disease is essential for devising control measure for the disease. Information on the sources of infection can often be gained by studying the distribution of infected plants within a crop which may in turn, suggest the method to be adopted in controlling the disease. Van der Plank (1946) has distinguished two kinds of spread, namely, random distribution and distribution in groups. He has suggested a formula for estimating random distribution of the disease within a crop. Using this formula studies were made on the pattern of spread of rosette disease in irrigated crop of TMV-2 variety of groundnut in the 1964 season at Coimbatore and Bhavanisagar.

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