See:
Greenhouse Plants, Tomato - Leaf Mold
Cause Passalora fulva (syn. Fulvia fulva, formerly Cladosporium fulvum), a fungus that is primarily a problem in greenhouse production. The fungus is most destructive when humidity is greater than 85% and the temperature ranges between 68°F to 75°F. The disease usually will not be severe if the relative humidity at the leaf surface is kept below 85%.
Symptoms White spots that rapidly enlarge and become yellow appear on the upper surfaces of older leaves. The patches' lower surfaces become covered with a velvety, olive-brown fungus growth. When the disease is severe, much of the foliage is killed, and the crop is greatly reduced.
Cultural control
- Treat seeds with a hot water treatment (122°F for 25 minutes).
- Stake and prune plants to promote air movement within canopy.
- Varieties reported resistant to some strains of the fungus include Santa Fe, Globelle (pink fruit), Bay State (red fruit), and Vetomold (red fruit).
Chemical control
- Affiance (Group 3 + 11) at 9 to 12 fl oz/A on 7- to 14-day intervals. Preharvest interval is 1 day. 12-hr reentry.