Suspected ‘die-back disease’ outbreak hits neem trees in Telangana
Agricultural scientists, however, assure that there was nothing to worry and are confident that the impact of the fungus would diminish on its own thereby leading to rejuvenation of the trees.
Hyderabad: Neem trees across the state are wilting and many drying up in what is suspected to be an outbreak of a fungus suspected to cause ‘die-back disease’, causing dismay and triggering an alarm among people.
Agricultural scientists, however, assure that there was nothing to worry and are confident that the impact of the fungus would diminish on its own thereby leading to rejuvenation of the trees. Scientists are busy trying to establish whether the ongoing wilting and drying was indeed die-back disease. But they advised people not to chop off the trees believing them to be dead as there is every possibility of the trees rejuvenating themselves. They also cautioned against using any pesticides and fungicides to check the ongoing wilting.
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Last year, a similar infection was reported from several parts in the State. Professor Jayashankar Telangana State Agriculture University (PJTSAU) has now constituted a Special Committee to inspect, assess the situation and initiate measures accordingly. The Committee has already inspected several areas, including the Agricultural Research Institute in Rajendranagar in September, where a high incidence of infection in Neem trees was noticed.
This apart, many areas in Rangareddy, Sangareddy, Wanaparthy, Gadwal, Nagar Kurnool, Karminagar, Warangal and other districts have been inspected and mapping is being taken up extensively to create awareness among farmers.
Scientists say there could be different reasons, including excess rainfall and high humidity during August and September leading to this problem.The infected neem plants showed different symptoms like complete wilting, drying of entire tree, drying of twigs and gummosis, Professor Jagadeeshwar from PJTSAU said.
Soil samples, young twigs, stems, bark etc were collected from the infected trees and were examined microscopically in September. It was observed alpha and beta conidia of Phomopsis Azadirachtae and Fusarium conidia (Macro conidia) were the causative factors for wilting, drying and die-back symptoms in neem trees, he explained.
The fungus does not pose any threat to humans or livestock. Fresh leaves, twigs and other parts of the infected tree can be used for different purposes, he said.
Generally, spraying of Carbendazim or application of Mancozeb Carbendazim on the affected parts, spray application of Thiamethaxom or Acetamaprid is taken up to reduce the incidence. However, spraying chemicals to control the spread of infection could be harmful. Chemical residues on leaves could be consumed by cattle and it could be harmful to them. Similarly, the chemicals could also pollute the nearby water bodies and drinking such water could also be harmful, he added, stressing that neem trees rejuvenate themselves.
While protecting huge trees from fungus infection could be practically challenging, experts emphasize on protecting the saplings in Haritha Haram nurseries. A coordinated effort by horticulture, forest and municipal administration was required to this effect, they said.
FCRI experts say not to worry on Neem tree fungus
Professors at the Forest College and Research Institute, Mulugu said neem trees were inherently tolerant to the dieback disease and survive the disease without any external intervention. However, pruning operations should be done with the help of an arborist, and diseased twigs should be removed and burnt to stop further spread during the next season, said FCRI Assistant Professor (Plant Protection) Dr. Jagadeesh Batthula.
He said the dieback of neem affects leaves, twigs in trees of all ages and sizes. Generally, the symptoms appear with the onset of rainy season and become progressively severe in the latter part of the rainy season and early winter season, he said in a statement here on Tuesday.
Disease management operations should start from the nursery stage as the pathogen was both seed borne and seed transmitted. During sowing stage, seed treatment with fungicides or biocontrol agents reduces the infection. At seedling and sapling stage prophylactic sprays of suitable fungicides like Carbandazim with 2.5 gram dosage per litre or bio-control agents like Trichoderma, which can surely improve sapling health and impart resistance against diseases, he informed.
Laboratory studies were conducted at FCRI, Mulugu and Phomopsis Azadirachtae was identified as pathogen. Dieback disease was always present in neem trees and severe infections were relatively rare, he added, “Our neem trees are very strong enough to combat the damage caused by dieback,”
