Question
newly planted tomatoes in greenhouse are showing brown blotches on leaves,think it may be mosaic disease,this is second time,destroyed first attempt,have over wintered geraniums and fuschias in same greenhouse, your comments please....

Answer
Hi Victor,

The most common mosaic that affects tomato is Tobacco mosaic virus.  This is characterized by yellowish-green blotches with pronounced leaf-curl evident and small blisterings of the leaves.  This does not sound anything like what you describe.  Most of the described mosaic diseases of tomato are virus related and have similar symptoms.

There are several diseases that give brown spots including Septoria leaf spot (_Septoria lycopersici_) and Early tomato (potato) blight (_Alternaria solani_).  Each of these can affect young plants, but they produce well defined, discrete brown lesions that are not usually described as a mosaic.  Some may have "halos" around the brown lesions.  (Mosaic usually describes a mottling of the leaf.) Again, by your description, this doesn't sound like your "mosaic".  

I would be interested to know whether there is any intermediate stage before the "brown" appears.  Are there areas of chlorosis (yellowing) before the areas become brown.  There are certain chemical deficiencies that can cause leaves to discolor.  Among them are phosphorous, manganese, and calcium.  If you are potting your seedlings in new potting medium (peat-based), then your minerals will be exhausted at approximately four weeks, earlier in warm wet conditions.  

I would encourage you to e-mail me a photo of the leaves.  Please get as close as possible, maintaining good focus. Also, did you seed these tomatoes or did you buy them already potted from a grower/retail source?  



The plants that you describe (Pelargonium spp. and Fuschia spp.) are not closely related to tomato or to one another, so the chance that there is a common link via a common pathogen is remote.  If you have not noticed any problems with the over-wintered specimens, and you have had no insect problems, it is very unlikely that those plants contribute in any way to the tomato symptoms you are visualizing.