Dieback disease

In News: Neem trees has been identified as twig blight and dieback disease in Telangana.

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.
• They can easily withstands pollarding (repeated lopping at heights above about 1.5 m)
• Neem shows antibacterial, antifungal, and other versatile properties
• But neem trees are sometimes hit by insect and fundal infestation

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.
• Even if treatment is carried out for one tree, the fungus spores from a nearby tree can affect the treated plant again.
• Spraying chemicals on big trees is a difficult task as it may hit insects like butterflies and also pollute water bodies nearby.

Source: The hindu