HYDERABAD: At a time cotton was sown in 50 per cent of the total sown area (18,61 lakh hectares) in Telangana, a serious threat to cotton farmers in the country and especially in the state has emerged in the form of Tobacco Streak Virus (TSV). Telangana being the third largest cotton producing state in country is now reported to be the worst affected by TSV among the cotton producting states.
A study titled ‘Tobacco streak virus: an emerging threat to cotton cultivation in India’ that was published last week in Phytoparasitica journal, has reported that TS was observed to have highest incidence rate of TSV among cotton fields surveyed across Telangana, Andhra Pradesh, Tamil Nadu and Maharashtra. The study was conducted by researchers from Department of Plant Pathology, TN Agriculture University.
The researchers calculated Percent Disease Incidence (PDI), which is the percentage of number of TSV infected plants out of the total number of observed plants, for the surveyed cotton fields in four states. They found that the mean PDI value for TS was 25.3 per cent and the maximum value was found to be as high as, a shocking 51 per cent. Compared to this AP had PDI of 16.47 pc, TN had a maximum PDI of 12.51 and in some filds it was completely missing whereas in Maharashtra mean PDI was just 6.22 pc.
Dr P Renukadevi, the lead author of the paper, told Express, “It was observed that in Warangal, from where the samples for TS were collected, the farmers were either not knowledgeable or were ignorant regarding thrips. They are very minute insects that infect cotton plant with TSV unlike Whitefly which is clearly visible. Moreover, it was observed that Partheneum was in close surroundings of TSV infected fields. While Parthenium does not get infected by TSV, its pollen can carry the virus and when it lands on cotton, it infects the plant.”
When contacted, Dr Vijaya Bhaskar Rao, Senior Scientist at the Regional Agricultural Research Station, Warangal said, “Since past few years, there has been a gradual increase in the occurrence of TSV. It can be easily controlled by spraying pesticide that kills thrips but the farmers must be made aware of the disease.”
The study also reported that TSV infection was severe in cotton hybrids compared to varieties and that in TN temperature, relative humidity and leaf wetness played a major role.