Shimla: Recently there were some reports received from the Baghi region of Shimla district regarding the problem of drying of branches and trees of cherry. Acting on these reports YS Parmar University of Horticulture & Forestry, Nauni rushed two teams of scientists of the university to the affected area.
A spokesman of the university said the teams interacted with the growers, assessed the conditions of the orchards and collected the diseased plant samples. An exhaustive survey of different orchards in Baghi panchayat was also done.
Sanjeev Chauhan, Director of Research at the university said the teams met with the affected growers to understand the severity of the prevailing problem and it was recorded that the problem was confined to Baghi and adjoining areas only.
Information was also gathered from the cherry growers in the Kandyali area which is not affected by the problem. Chauhan said in all the affected plants, leaf yellowing, tattering, reddening and bronzing symptoms were observed which were found slowly spreading to the entire plant leading to the death of the affected plant.
The roots of the infected plants were found healthy which ruled out the association of any soil-borne fungal or bacterial pathogen with the affliction.
The systemic nature of infection and symptoms matched closely with phytoplasma, a kind of phloem-limited cell wall-less bacterium. Therefore, the samples were further subjected to laboratory testing and the presence of phytoplasma was confirmed through fluorescence microscopy.
The spread of this pathogen is through an insect commonly called leaf hopper. The parts of the leaf hopper collected around the affected trees were also examined through fluorescence microscope and the presence of phytoplasma was confirmed.
To apprise the farmers about the management and control the spread of this disease, the University will be organizing awareness camps in the affected areas in September-October.
The university has further recommended the following ad-hoc management practices to control this disease in cherry trees.
Make holes in the trunk of the affected trees and pour oxytetracycline hydrochloride (OTC-HCL) antibiotic @ 2 g and citric acid @ 10 mg dissolved in 10 ml of water drop by drop through these holes with the help of a pipette. Plug the holes with clay soil and FYM paste (1:1 w/w) after the absorption of the solution.
Spray Imidacloprid 17.8% SL @ 50 ml/200 L of water or Oxy-demeton Methyl 25 per cent EC @ 200 ml/200 L of water for the control of leaf hopper vector.
Avoid the use of bud sticks from symptomatic trees as the infected plants serve as the source for spread of the phytoplasma.