Biosynthesised silver and copper nanoformulation as foliar spray to control bird's eye spot disease in tea plantations

Tea leaves have economic importance in preparation of the popular beverage of the world “tea”. Bird’s eye spot disease of tea leaves creates significant revenue loss in tea trade of many tea plant cultivating countries. Management of this disease by silver (AgNps) and copper (CuNps) nanoparticles that are biosynthesised by efficient antagonists was studied. The biocontrol agents like Pseudomonas fluorescens, Trichoderma atroviride and Streptomyces sannanensis were evaluated for nanoparticle synthesis against Cercospora theae isolates namely KC10, MC24 and VC38. Initially, the freshly prepared extracellular AgNps showed high disease control (59.42 – 79.76%), but the stability of antagonistic property in stored nanoparticles were significantly high in CuNps (58.71 – 73.81%). Greenhouse studies on various treatments imposed also showed reduced disease incidence percentage of 13.4, 7.57 and 10.11% when treated with CuNps synthesized by P. fluorescens, T. atroviride and S. sannanensis respectively. Various treatment schedule in fields suggested the use of Bionanocopper@1.5 ppm for highest yield (3743 kg/ha) with 66.1% disease prevention. The results suggest the use of biosynthesised CuNps using Streptomyces sannanensis for controlling the tea plant pathogens causing foliar disease with higher stability in releasing the antagonistic activity during sporadic disease incidence of bird’s eye spot disease in tea plants.Inspec keywords: silver, copper, crops, plant diseases, nanoparticles, air pollution, agrochemicals, nanobiotechnologyOther keywords: biosynthesised silver, biosynthesised copper, nanoformulation, foliar spray, bird eye spot disease control, tea plantations, tea leaves, economic importance, revenue loss, tea trade, tea plant cultivating countries, silver nanoparticles, AgNps, copper nanoparticles, CuNps, biocontrol agents, nanoparticle synthesis, Cercospora theae isolates, KC10, MC24, VC38, greenhouse studies, antagonistic property, P. fluorescens, T. atroviride, S. sannanensis, fungicides, synthetic nanomaterials, bionanomaterials, disease prevention, green leaf yield, BionanoCu, tea plant pathogens, foliar disease     

Antifungal activity of biosynthesised copper nanoparticles evaluated against red root-rot disease in tea plants

The synthesis of metal nanoparticles is an emerging area of advanced research and technology with potential application in plant protection. In the current study, with an eco-friendly approach, a convenient method was adopted, where copper nanoparticles are biosynthesised extracellularly by using Streptomyces griseus. Further, the existence of nanoparticles was confirmed by UV–visible spectroscopy, transmission electron microscopy, X-ray diffraction analysis and Fourier transform infrared spectroscopy characterisation. We assessed the field effectiveness of copper nanoparticles through soil application in P. hypolateritia infested tea plants. In response to seven different treatments, carbendazim exhibited superior control followed by nanocopper at 2.5 ppm dosage. However, maximum leaf yield was observed in plants treated with nanocopper. In addition, nanocopper-treated plants showed improved soil macronutrients considerably when compared to bulk copper and carbendazim treated plants. In addition, there was trivial variation in population dynamics of microbes noted in plants treated with nanocopper. These encouraging results confirmed that nanocopper could act as an efficient novel fungicide which may be used for the management of red root-rot disease in tea plantations.