I have a bad case of gray mold on my tomatoe plants in my greenhouse, I also have had a large fan on them all the time. In the past years I have been alble to trim it out . will I have to clean every thing with bleach and change all soils at end of season in order to replant tomatoes next year?
You will have to thoroughly clean and sanitize the greenhouse before attempting further production.
As for this year, remove all dead and dying plant parts on and around plants and take them out of the greenhouse, maintain a relatively dry environment (humidity below 90%), increase spacing between plants for better air circulation, and avoid splashing water on foliage during watering. Definitely use your fan for increased air circulation.
Also, eliminate weeds from inside the greenhouse and around doorways and vents outside the greenhouse.
A calcium to phosphorus ratio of 2 or higher will help in the control of Gray Mold.