The Association said rainfall in upper Assam, lower Assam, Dooars, Terai and Darjeeling was lower by an average of 60 per cent.
The estimated crop loss in Assam only during the period was estimated to be around 23 million kg, ITA said in a statement.
ITA said till March, barring Darjeeling and Terai, there was some gain in crop, however the situation deteriorated badly from April to May.