Dieback disease - The Hindu - 29/12/22

Context:
Neem trees has been identified as twig blight and dieback disease in Telangana.
Relevance:
GS1
About:
->Neem:
-Neem is a member of the mahogany family, Meliaceae. Neem trees are attractive broad-leaved evergreens that can grow up to 30 m tall and 2.5 m in girth.
-The roots penetrate the soil deeply. When injured, they produce suckers – This suckering tends to be especially prolific in dry localities.
-It is grown from the southern tip of Kerala to the Himalayan hills, in tropical to subtropical regions, in semiarid to wet tropical regions, and from sea level to about 700 m elevation.
-Neem trees are strong can take considerable abuse.

->Dieback disease:
-The dieback disease affects leaves, twigs and the inflorescence of neem trees of all ages
-It causes almost 100% loss of fruit production in severely infected trees
-The dieback disease is mainly caused by the fungi Phomopsis azadirachtae.
-The dieback disease was first reported in the country during the 1990s near Dehradun in Uttarakhand, while it was first noticed in Telangana in 2019.
-The appearance of symptoms starts with the onset of the rainy season and becomes progressively severe in the later part of the rainy season and early winter.

->Control measures:
-The twigs affected by the disease should be cut and a blend of fungicide and insecticide can be sprayed after their removal.
-Alternatively, a pit should be dug around an affected tree, and water mixed with fungicide and an insecticide should be poured into it.
-However, the efforts to treat the affected trees should be taken up as a cluster either in a village or in a residential locality in urban areas as the fungus is airborne.
-Spraying chemicals on big trees is a difficult task as it may hit insects like butterflies and also pollute water bodies nearby.

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