LAKHIMPUR KHERI, May 2 -- Suresh Pal of Bhangaiyachat village in Nighasan tehsil of Kheri district stood desolately in his orchard, staring at his mango trees that had promised a bumper harvest this year.

"Among the 35 mango trees in my orchard, I expected a good crop as all the trees bore a rich blossom, or 'baur', this season," he said, tracing the soot-like residue on a withered branch. "However, for reasons I don't know, all the 'baur' withered and darkened, shattering my hopes of a good harvest," he added.

Suresh Pal's experience is not an isolated case.

"A similar trend is being reported across the mango belts of the Terai region and other parts of north India this season, where an initially promising bloom has largely failed, af...