What evidence in the text supports the theory that the fire may have been set on purpose? If this is the case, who set the fire?

From the text:

Mr. Jamison pulled off his hat and ran his fingers through his hair, damp against his forehead. Then, squinting, he looked over his shoulder at the field. 'Folks thinking.' he said slowly, as if he did not want to say what he was about to say, 'folks thinking that lightning struck that fence of yours and started the fire...' He pulled at his ear. ‘It’s better-, I think, that you stay clear of this whole thing now, David, and don't give anybody cause to think about you at all, except that you got what was coming to you by losing a quarter of your cotton...'

There was a cautious silence as he gazed up at Papa and Mr. Morrison, their faces set in grim, tired lines. '... Or some- body might just get to wondering about that fire...'