White mold (aka timber rot) has been observed occasionally on Long Island in tomatoes growing in the field and in high tunnels. Other crops observed affected in the area include pepper, lettuce, and cabbage.
Diagnostic feature for white mold is the black, hard structures resembling rat droppings the pathogen forms on or in diseased tissue (sclerotia). These are inside tomato stems that are white and dry because of the disease. Sclerotia are how the pathogen survives for many years. It is worthwhile, especially in high tunnels, to remove affected plant tissue and thus the pathogen’s survival structures.