Different Kinds of Tomato Blight and How to Tell Them Apart

At least two common tomato problems are referred to as tomato blight and another one is often thrown into the same mix:

• Early blight
• Late blight
• Septoria leaf spot

They’re each caused by a different fungus. You can tell these three problems apart by what they look like, what parts of the tomato they affect, and when their symptoms appear. But the good news is this: all three can be treated and controlled similarly with biofungicides or fungicides and by practicing good preventative care.

	Early Blight	Late Blight	Septoria
Photo	Photo: University of Minnesota Extension	Photo: Iowa State University	Photo: Cornell University
Cause	fungus: Alternaria solani	fungus: Phytophthora infestans	fungus: Septoria lycopersici
Characteristics	Dark, concentric spots ¼ - ½” on lower leaves and stems Spots on fruit near stems Lower leaves yellow and drop	Blue-gray spots on leaves which turn brown Dropped leaves Irregular brown, greasy spots on fruit White mold rings on spots	Small black or brown spots on the lower leaves Lower leaves yellow and drop
Parts affected	leaves stem fruit	leaves stem fruit	leaves stem
Timing	early- to mid-season in wet weather	mid- to late-season in wet weather	early- to mid-season in wet weather

Tomato problems from diseases

How to identify and treat early blight ...

How to identify and treat late blight ...

How to identify and treat Septoria leaf spot ...

How to identify and treat gray leaf spot ...

How to identify and treat fusarium wilt ...

How to identify and treat verticillium wilt ...

How to understand tomato disease resistance codes ...

How to choose a garden sprayer that is best for you ...


Tomato pests

Tomato hornworm: how to identify and control it ...

Tomato worms-cutworms: keep them away with stem collars ...

Stink bugs: how to identify and control them on tomato plants...


Tomato problems from growing conditions

Blossom end rot: how to identify, treat, and prevent it ...

Why a tomato cracks and what to do about it ..

Tomato sunscald: why too much sun can be hazardous to tomatoes...

Blossom Drop: why fruit doesn't set and what to do about it ...

Are bumps on tomato stems harmful to plants?

How to identify tomato problems and prevent them...

Return from Different Kinds of Tomato Blight to Tomato Dirt home