Hi 

I have special thanks in advance for your cooperation.

I talked a bout this disease with owners greenhouse, he said me this disease has been developed in cold weather and was transferred Easily by hands. 

I prescribed  Applying  fungicides that control Fungus alternaria that is produced by Bayer company entitled Nativo. What do you think about it???

Leaf mold, caused by the fungus Fulvia fulva (synonym Cladosporium fulvum), is a common and destructive disease on tomatoes worldwide grown under humid conditions. Leaf mold is primarily a problem on greenhouse tomatoes, but occasionally develops on field and garden-grown tomatoes if conditions are favorable. The disease is most destructive in the greenhouse during the fall, early winter, and spring when the relative humidity is most likely to be high, and air temperatures are such that heating is not continuous. Whenever possible, keep the relative humidity in the greenhouse below 85 percent, and keep free moisture from forming or persisting on leaves. This will inhibit the development and spread of the

leaf mold fungus.a. Provide good ventilation and as much light as possible. Circulate air with fans to eliminate dead-air pockets. b. Keep night temperatures in the greenhouse warmer than outside air temperatures. If leaf mold becomes a problem, some night heating may be needed in Illinois through late spring and again in early fall. c. Attempt to avoid wetting the leaves when watering. Water early in the day to allow leaves to dry by mid-afternoon. d. Maintain a temperature of at least 60° to 65°F (16° to 18°C) throughout the season. e. Provide adequate plant and row spacing to avoid excessive shading.

Hi Mr Ravi Kant Upadhyay 

thnks a lot for your attention you.

You can apply the following active ingrediends:

mancozeb

chlorothalonil

zoaximide + mancozeb

mandipropamid + difenoconazole

Nativo ( trifloxystrobin and tebuconazole)

trifloxystrobin belong to Chemical Family:Strobilurins / local penetration

tebuconazole belong to Chemical Family:Sterol Inhibitors / systemic upward

Hi

thanks so much

All previously mentioned answers are quite good, but I think that there is very important point was neglected.  Its well established that this pathogen contains very high account of races, therefore its very important to identify the most prevalent races in your place and chose one of the most resistant variety to decrease disease severity.  

Dear Elaheh,

probably my comment is taken for granted, but to add a point to the useful comments above, do not forget -whenever possible and available - to use resistant tomato cultivars/hybrids.