"Blight" has become a bit of a generic term. It gets applied to any leaf disease. There are only really two "blights" - Early (very common in the home garden) and Late (uncommon in the home garden). Most of the fungal and even some of the bacterial diseases have similar sorts of symptoms. It takes practice and a keen eye to tell them apart.
Anyways, brown spots can be fungal but a bit more detail would help. Are they simply spots? Or is there any sign of a "halo" around them?
This, for example, is Septoria Leaf Spot, probably the most common fungal problem in the domestic garden:
This is Early Blight, which rivals SLS for frequency in the domestic garden:
The identifier for Early Blight is those tiny rings you can see within the enlarged brown spots.
How exactly do your spots look, f&n?
