In these cases, it is best to look at the plants in the early morning, while the leaves are still wet from dew. A leaf may also be removed and put in a plastic bag with a piece of moist paper towel and left overnight, usually at a normal room temperature. Spot Gray mold and ghost spot diseases of tomato are caused by the fungus Botrytis cinerea . Botrytis causes disease in practically all plants, including tomatoes. The fungus is everywhere, especially in greenhouses.
Plants become more susceptible as they get older.
Plants with dense or succulent foliage are most heavily damaged. The disease causes a loss of leaf area and fruit quality, including losses during storage and shipment. Light tan or gray spots appear on leaves, which become covered with gray-brown fungal growth. The leaf later collapses and withers. The fungal growth is dense and may resemble felt.