Tuesday, April 12, 2011


My friend Theresa (Hi Theresa - thanks for looking at my blog!!) asked me on facebook about tomato blight so I thought my first post-introductory blog would be all about this ferocious fungus and how to fight it! (Theresa, don't feel guilty - we got it last year too!) Tomatoes are my favorite garden food, especially the heirloom Black Prince and Black Krim from Eastern Europe. I could eat these tomatoes every day! So, last year, when our tomatoes were infected, I did the research after the fact and learned how I could have prevented this loss! Early blight can affect the Nightshades, which include both potatoes and tomatoes. It is caused by a fungus called Alteranan Solari (yes, I googed it!) and like any fungus, the spores are carried by the wind and can arrive in your garden soil through no fault of your own. When your tomato plant is infected, symptoms (like the ones pictured!) usually start at the bottom of the plant and move up. Brown sores and yellow discoloration appear on the tips of the leaves and gradually overwhelm larger portions of the plant, even affecting the fruits. In this blog, I'll go over what to do to prevent blight, what to do when your plants are infected, and what to do in the following seasons...

    If You Have Never Had Blight...

  • Remember that fungus thrives in humid, moist, cloistered environments. Don't be shy about watering, but take the steps to make sure your tomatoes don't breed these conditions!

  • Water in the morning, so that afternoon sun dries any water that splashed up.

  • Stakeyour tomatoes early and don't plant them too close together! (Voice of experience speaking!)

  • By the way, water regularly. Dry periods followed by wet periods followed by dry periods cause that cracking that you sometimes find in tomatoes.

  • Choose healthy plants to begin with.

  • A fungicide (chlorothalonil) can be purchased online or in garden stores to prevent this fungus. But I don't know how this might diminish your dreams of an organic garden!

  • Mulch. This creates a barrier between your plant and the soil below that may harbor the fungus. This year Reed and I are trying a red plastic mulch layer that is supposed to increase yield by bounched far-red light back to the plant. Will let you know how that works out!

  • Plant in full sun where the soil is suitably drained.

If you find Blight on Your Plant...

  • You can pull the infected leaves off the plant. This will slow the spread, but isn't a cure. Apply fungicide according to directions. If you choose to pull up an infected plant, do not put it in the compost!

The Season After the Blight...

One of the most infuriating things about Blight is that it lies dormant in your soil for 3 years or more after infection. So, if you plant your tomatoes in the same place, these healthy plants are likely to become infected too.

  • Practice crop rotation and don't plant nightshades where it appeared before.

  • Plant in raised beds or a clay pot if you are truly worried about it.

  • Compost well!
That's about the summation of my knowledge on this topic! If you can add anything at all - please let me know in the comments section!!

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