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ABSTRACT
Impact of time of sowing and sun drying of cotton stalks and on the management of cotton stem weevil , Pempherulus affinis Faust was studied at Cotton Research Station, Srivilliputtur, Tamil Nadu. In early sown cotton crop infestation and plant mortality was more compared to the late sown cotton crop. It was also observed that off season crop (i.e., Winter season crop in the Summer Cotton Tract) was much affected compared to the regular season crop (i.e.,Summer season crop in the Summer Cotton Tract). Weevil emergence was nil from sun dried cotton stalks kept under sun in situ after pulling out. But weevil emergence was observed in stored / heaped cotton stalks. Importance of in situ drying of cotton stalks after pulling out the cotton stalks to arrest the carry over of the pest to next season is brought out in the present study.
Key words: Cultural method of pest control, cotton, stem weevil, Pempherulus affinis, effect of sun drying, time of sowing
INTRODUCTION
Stem weevil, Pempherulus affinis is not a serious menace in regular season crop and only less than 10 % mortality of plants is encountered. Of the economically important insect species, next to bollworms, the cotton stem weevil, Pempherulus affinis has been reported as a major pest in South India (Murugesan, 1988; Chandramani et.al., 2006). While discussing the seriousness of stem weevil in South India compared to Northern parts Krishnaayyar (1942) opined that extremes of climatic conditions in South India are not sufficient great to offer an effective check on its multiplication as in other parts of India. Growing cotton during the dry (winter) season avoids many insect pests endemic in the wet season (summer) and could permit the reintroduction of cotton to the semi-arid tropics in many parts of the world (Yeates et al., 2010).
In the recent years, farmers tend to raise cotton during the off-season i.e., during winter season in summer irrigated cotton tract viz., Madurai, Theni, Salem, Erode, Dindigul and Virudhunagar districts. Similarly, farmers of winter cotton tract opt for an additional summer crop. Under such conditions, mortality of cotton plants due to stem weevil is more than 60 % and becoming serious botheration to cotton growers. Moreover, in the off season (winter season in...