Tomato Trouble – Late Blight

| organic gardening

Tomatoes are a magical fruit - it seems that almost everyone who has a vegetable garden, or wants a vegetable garden, dreams of luscious, sun warmed tomatoes picked fresh from the vine.  I love when my tomatoes start to ripen and the avalanche of fruit hits the kitchen - I have yet to find my fill of tomatoes!

sun ripe tomatoes by mailelani

As much as they can be relatively easy to grow, tomatoes come with a list of potential diseases. First and foremost - we need to talk about late tomato blight.  Late tomato blight will kill your plants - causing them to collapse almost overnight.   And sadly, late blight  has started to appear in parts the United States, and it's arrival has sparked an cascade of emails, Facebook posting and warnings.

All blight photos below from Cornell University, Long Island...visit their page for more information and photos

Last summer was a terrible season for tomatoes here in the Northeast.  We had a huge tomato blight outbreak, fueled by diseased tomato plants being sold at chain stores.  Each of those infected plants was host to millions of spores of the Phytophthora infestans pathogen.  These spores spread and spread and before we knew it tomatoes were a rare commodity. Farmers lost entire harvests and thousands of dollars, home gardeners were deprived of their bounty and we were once again reminded of our inability to manage all that nature throws our way.

I cannot emphasize enough how nefarious this disease is. Late blight requires immediate community response - if you see affected plants in your garden immediately pull them and the plants right next to them (even if they appear to be healthy) double bag them and either incinerate or send them to the landfill. DO NOT COMPOST!  Let your neighbors and local county extension service know - everyone needs to be on board with this.  The Irish potato famine was caused by this pathogen and its control is on the top of the list for those of us who love tomatoes.

If blight has been spotted in your area monitor your plants everyday, several times of day. It appears quickly and must be dealt with quickly.

Late blight overwinters in infected potatoes left in the ground and is hosted in the wild tomato seedlings that pop up from last year's seeds.  Search your garden beds for these uninvited plants and treat them as you would poison ivy amongst your basil - no tolerance.  Pull them out and burn or trash them.  Again - do not compost them.

Prevention and  control is the only remedy for tomato blight.  There is no real treatment for it - organic or otherwise.  Do yourself and your community a favor and destroy infected plants.  There are fungicides that can be used as a preventative, but in my experience compost tea applications are a much healthier and safer choice.  But this is a preventative - if you see the blight on your plants no amount of compost tea will save them....burn them or throw them away.

More resources on late blight...please read these and familiarize yourself with the symptoms of and ways to prevent this terrible disease:

Connecticut Agricultural Experiment Station Fact Sheet

Cornell University - Long Island

Rodale Institute


Cornel University

Caroline Finnegan owns Ladybug Landscaping, a full service organic landscaping company. based in CT. She is a NOFA accredited landcare professional and when not designing gardens can be found rearranging her furniture or out at a flea market finding new goodies. She almost always has dirt under her nails.


  • That’s horrible, and I had no idea it existed. Thanks for letting your readers know.


  • This is very good to know. Thanks for the information. Last year we had problems with our tomatoes turning black on the bottoms of them. I think I read that it had something to do with the amount of rain we had gotten. But this year (after fighting aphids) we’ve produced great tomatoes!

  • love tomatoes! we are about to put out another round for fall crop down here. yum yum yum. great info, Caroline!

  • Caroline, I love any post that uses the word ‘nefarious’!

    Those nasty, infected photos might put me off tomatoes for life!! I thought compost tea was the magic cure-all for everything? Famine, war, celebrity drug addiction….

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