International Journal of Plant Protection

A. Ravikumar ¹, C. Chinniah ¹, S. Manisegaran ¹, S. Irulandi ², P. Mohanraj ³

Affiliations
1 Department of Agricultural Entomology, Agricultural College and Research Institute, Madurai (T.N.), IN
2 Krishi Vigyan Kendra, Pechiparai (T.N.), IN
3 Tamil Nadu Agricultural University, Coimbatore (T.N.), IN

Abstract

The present investigation was carried out to test the efficacy of biorationals against thrips, Scirtothrips dorsalis Hood on chilli. Field experiments were conducted at farmers holding during September 2009 - Febrauary 2010 and November 2009 - April 2010. Among biorationals tested, spinosad 45 SC @ 0.4ml 1^-1 and emamectin benzoate 5 SG @ 0.4g 1^-1 was found to be superior to the standard check dimethoate 30 EC @ 2ml 1^-1 registering the least population of 0.55 and 0.59 / leaf, followed by Beauveria bassiana @ 1 x 108 spores ml^-1 and neem oil 3 per cent which recorded thrips population of 1.01 and 1.11 / leaf. With regard to leaf curl damage by thrips, spinosad 45 SC @ 0.4 ml 1^-1 and emamectin benzoate 5 SG @ 0.4g 1^-1was very effective. Highest dry chilli yield of 1509 kg ha^-1 was registered in spinosad 45 SC @ 0.4ml 1^-1, which was on par with emamectin benzoate 5 SG @ 0.4g 1^-1 (1525 kg ha^-1) with respective additional income of Rs. 30,300 and Rs. 26,400. The highest cost benefit ratio (1:4.30) was obtained in spinosad 45 SC @ 0.4ml 1^-1 followed by 1:4.30 in emamectin 5 SG @ 0.4g 1^-1.

Keywords

Biorationals, Thrips, LCI, Yield, Chilli.

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B. Bebitha ¹, P. Mohanraj ², S. Manimegalai ³, C. A. Mahalingam ⁴

Affiliations
1 State Department of Horticulture, Kanchipuram (T.N.), IN
2 Directorate of Extension Education, Tamil Nadu Agricultural University, Coimbatore (T.N.), IN
3 Department of Sericulture, Tamil Nadu Agricultural University, Coimbatore (T.N.), IN
4 Department of Entomology, Tamil Nadu Agricultural University, Coimbatore (T.N.), IN

Abstract

Silkworm has a greater biotic potential and the resistance is continuously offered by the environment which includes biotic and abiotic factors thus influencing the cocoon production qualitatively and quantitatively. The abiotic environmental resistance component largely includes the weather factors such as temperature, relative humidity, photoperiod etc., in respect of silkworm and unfavourable weather conditions that lead to poor harvest of mulberry. The abiotic factors usually affect the growth and development of silkworm and predispose the silkworm to the biotic causes i.e., infectious diseases. The biotic factors responsible for low cocoon crop production are the silkworm diseases caused by protozoa, fungi, bacteria and viruses. Extent of crop loss due to fungal disease caused by white muscardine and green muscardine was 5-20 per cent,virus disease caused by grasserie (NPV) was 15-20 per cent, bacterial disease reduces the crop loss upto 10-15 per cent and pebrine gives 5-10 per cent damage, respectively. The history of sericulture reveals devastating impact of microsporidiosis in several sericultural countries resulting in severe damage to sericulture industry. Though, the disease is known from very remote times, it attracted the attention of sericulturists only during the 17th century. The first scientific record of the occurrence of the disease came from European countries in 1809 and the disease wiped off sericulture there. This was followed by another report from France in 1845 where the annual production of cocoons came down from 26,000 tones in 1853 to 4000 tones in 1865 due to epizootics of microsporidiosis and subsequently collapsed the French and Italian silk industry. Later the disease spread to Spain, Syria and Romania (Steinhaus, 1949). In India, the first report of the occurrence of the disease was from Mysore in 1866 followed by an epidemic level outbreak of the disease in Kashmir in 1878 (Baig et al., 1997).

Keywords

Silkworm Disease, Relative Humidity, Photoperiod.

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