Management of blight disease of litchi (Litchi chinensis) caused by Alternaria alternata

Abstract

Litchi or Lychee (Litchi chinensis Sonn.) is a member of the Sapindaceae family and is regarded as one of the most popular and nutritious fruit. Blight, in the form of leaf, panicle and fruit, was observed in litchi plants cultivated at the farm in ICAR-National Research Centre on litchi, Muzaffarpur, Bihar (India). Based on disease severity, an attempted was taken to control this newly emerged disease caused by Alternaria alternata using different fungicides and bio-control agents in laboratory, glass house and field conditions. Among different fungicides, Difenoconazole at 1000 ppm, Copper Oxy chloride at 1500 ppm, Azoxystrobin at 2000 ppm completely inhibited (100%) mycelial growth of A. alternata under in vitro condition. Two indigenous bio-control agents viz. Trichoderma viride (NRCL T01) and Bacillus subtilis (NRCL BS01) showed 63.3% and 53.8% of Percent Inhibition of Radial Growth (PIRG) of Alternaria alternata in dual culture plate respectively. In glass house condition, Azoxystrobin (PDI=16.7% and PDC=80.2%), Difenoconazole (PDI=18.5% and PDC=78.0%), Thiophanate methyl (PDI=19.3% and PDC=77.1%) and Copper oxy chloride (PDI=24.4% and PDC=70.9%) were found to be highly effective in reduction of leaf blight. In addition to this, for management of panicle and fruit blight, experiments were also conducted in field condition at season 2017 and 2018 where almost same trends of effectiveness of fungicides were observed. Besides, bio-control agents viz. Trichoderma viride (NRCL T01) and Bacillus subtilis (NRCL BS01) also reduce the incidence of both panicle and fruit blight. Present study is not only giving a promising solution to minimizing the loss caused by Alternaria alternata in litchi by using available commercial fungicides but is also providing an alternate option of using eco-friendly bio-control agents.