Target Spot is another fungal disease. All above ground parts of the plant may be attacked. Fruit lesions may be a problem. Given the cooler temperatures, early blight may not be a problem. It is not a very common disease because many greenhouse tomato varieties have some resistance.
Symptoms are a pale green to yellow flecking of the upper surface of the leaves.
When the leaf is turned over, a greenish mold may be associated with the colored areas. Timber rot is caused by Sclerotinia sclerotiorum . This fungal disease will be more common in greenhouses which have been infected in the past. Without careful removal of the diseased vines, the hard resting structures which were produced inside the stem will fall out. Some will be located in an area where they can germinate and produce spores.