A low cost method for early detection of airborne Puccinia rust spores using glass slides and foldscope in the sugarcane field

The rust pathogens ( Puccinia spp.) affect many cereals, pulses and sugar crops causing a major threat to crop production and productivity throughout the world. The sugarcane crop is being affected by Puccinia melanocephala and P. kuehnii causing brown and orange rust respectively. Sugarcane rust is an important constraint in popularizing the new and high potential varieties due to its appearance on the foliage. Under the changing climatic conditions many popular cultivars are showing rust infection from mild to severe form depending on the weather conditions during the crop seasons. Being an obligate pathogen, the rust is present on sugarcane throughout the year but the appearance and severity is highly influenced by the weather parameters such as temperature, relative humidity and the physiological maturity of the crop. Trapping the uredospores using Vaseline coated microscopic glass slides helped to determine the inoculum load at various time intervals in the air. The uredospores can be observed with the help of Foldscope, which broadens the scope of detection of uredospores without depending on the compound microscope in remote areas. By connecting with the mobile phone, the spores can be photographed and digital pictures can be shared for further confirmation. The frequency and quantity of the uredospores trapped will help in quantifying the spores in the field for management of sugarcane rust well in advance before the appearance of the symptoms in hot spot areas. This simple tool will be a boon for detection of rust spores in the field during the latent period before the appearance of the symptoms thus enabling management of rust in time.