What was identified as the active substance causing the Bakanae disease in rice seedlings?

Step-by-step solution

The ‘bakane’ (foolish seedling) disease of rice seedlings, was caused by a fungal pathogen Gibberella fujikuroi. E. Kurosawa reported the appearance of symptoms of the disease in uninfected rice seedlings when they were treated with sterile filtrates of the fungus . The active substanceswere later identified as gibberellic acid.