Hundreds of mango trees in the district have been affected by dieback disease, locally known as aga mora, much to the worry of growers in the area famous for producing a variety of quality mangoes.

At least 17 trees that died of the disease were removed from the orchard of the district administration at Court Bagan in Chapainawabganj town recently.

The disease usually affects trees from the tip and spreads downward, causing cracks on the infected stem and numerous pycnidia are formed on dead twigs.

Twigs die, giving a scorched appearance to the limb.

The young green twigs start withering first at the base and then extend outwards along the veins of leaf edges, said scientists of Regional Horticulture Research Station in Chapainawabganj.

The affected leaf turns brown and its edges roll upwards. Leaves scorch and fall, leaving a dead branch.

In severe condition, branches dry one after another and the whole tree dies eventually.

It is a fungal disease caused by lasiodiplodia-theobromae, scientists said after observing the affected trees at different places in the district.

The disease, which normally spreads from November to March, has affected quite a few orchards in the district, causing death even to old trees.

If the disease could be detected at initial stages, the trees could be saved by using Bordeaux paste, said Dr Shorof Uddin, a senior scientific officer of the research station.

"The pathogen can live on dead wood and bark of dead trees and twigs where the spores are released by air and spread to healthy trees. Spread of the disease can be checked by removing dead trees," he said.

Regular monitoring and integrated pest and disease management techniques can help reduce loss of mango yield, he added.

Mango is the most important cash crop in Chapainawabganj that produces nearly 350 varieties of the delicious summer fruit, said sources at Department of Agriculture Extension (DAE) and Regional Horticulture Research Station.

Some of the well-known commercially grown varieties are gopalbhog, khirsapat (himsagar), fazli, langra, lakkhanbhog, and ashwina.

Last year, 2.30 lakh tonnes of mango was produced from 18.50 lakh trees on 24,250 hectares of land in the district, DAE sources said.