Are My Tomatoes at Risk?

Late Blight symptoms on tomato leaves - water-soaked lesions.

Late Blight symptoms on tomato leaves - water-soaked lesions.

Can you relate to the kind of sinking feeling in your stomach that happens when you think of a summer without tomatoes! That is what happened to me when I found out the Irish potato famine fungus is “out there”…in Rhode Island [and the rest of the Northeast]. Yikes! Late blight! My tomatoes are at risk! First I panicked, and then I decided to get some useful, factual information about this.


OK, so the reason for raising the caution flags is that while late blight occurs sporadically in the Northeast in any given year it is different in 2009 compared to most seasons. One reason is that it is the earliest this disease has been reported over such a broad region of the country. Then, more tragic for the Northeast, is that infected plants have been distributed to large local retail stores from Maine to Ohio. Never before has such an extensive distribution to local retail stores occurred. The problem is this fungus is exceptionally contagious.


Symptoms of Late Blight on tomato fruit.

Symptoms of Late Blight on tomato fruit.

Here’s what we need to know. The symptoms that develop on tomato leaves, stems, and fruit are quite dramatic and they are obvious to the naked eye. (That’s a relief.) The leaf lesions appear water soaked when the foliage is wet and their edges will be covered with white fungal growth. When the lesions dry out they may appear lime-green or beige in color. This is a good start for identification, but when you see brown to black lesions on the stems…and on the fruit…you KNOW your plants are infected. Here’s the good news: you can still eat the fruit after you remove affected areas because the fungus is not harmful to humans. However, if you have infected plants you must remove the plants from your garden immediately and put in plastic bags for disposal. DO NOT COMPOST.


Tomato stems infected with Late Blight fungus.

Tomato stems infected with Late Blight fungus.

Here are your choices: Spray your tomatoes with a fungicide (must contain the chemical chlorothalonil, as, for example, Daconil) that is a protectant and could keep your plants from being infected. The bad news: the chemical is a carcinogen. The alternative is to do nothing, check your plants daily, and be prepared to give them up if you see any symptoms. The most important thing is that you act quickly to avoid spreading the fungus beyond your garden to neighbors or a nearby commercial grower.


My advice: Enjoy those BLTs…and don’t panic!

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7 Responses to Are My Tomatoes at Risk?

  1. beth says:

    It seems that your tomato are at risk. BTW nice blog. Keep it up the good work.


  2. Kathy Girard (HerbDoc) says:

    Thanks for posting the information on the late blight fungus! It truly has panicked local gardeners but will mostly present a problem for commercial growers of tomatoes and potatoes. I too wouldn’t use Daconil as a preventitive measure. Bordeaux mix (copper sulfate and hydrated lime) is an accepted organic farming control provided that the number of applications is strictly followed to prevent copper accumulation in the soil. It can be purchased premade and should be applied early in the morning on a dry and sunny day. Bordeaux mix may not be as effective as the chemical Daconil but it is said to control many problems incuding flea beetles, anthracnose, bacterial blight and wilt, black spot, powdery mildew, rust and late blight.
    Personally if I spotted late blight on my plants they would be immediately removed, bagged up and trashed. Gardeners need to know that there is nothing they can do to save already infected plants.



  3. Layanee says:

    So far so good with my tomatoes but then again I didn’t buy them at the box store which purchased them from Annie’s in Alabama where the outbreak is thought to have originated. Those are good pictures of the fungal disease.


  4. Thank you for this very informative post, which I found via a posting from The Brooklyn Kitchen. We bought our plants at the SCLT plant sale and so far, all appears to be well, but this is frightening, and all the more reason to buy local from people you know and trust.


  5. dirtynailz says:

    Thanks for your comment, Jennifer. I love your blog!



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