Dan's Gardening and Birding Blog: Tomato Blight

Welcome back and as always, thanks for reading.

As promised, I am writing a post about tomato blight.You probably have heard about early blight, late blight, and more. In this post I will try to break them down and provide prevention and control tips.

Over the last few weeks, I have noticed that my tomato plants have developed some early blight. Although this can be a little discouraging, this is not unusual at this point in the gardening season. Both types of blight thrive in warm and humid conditions.

Early blight occurs at this time of the growing season. Late blight occurs later on as the name implies. These two blights are caused by different organisms, both of which are fungi.

The differences are very well explained on the following site: http://organicgardening.about.com/b/2009/07/05/diagnosing-tomato-diseases-is-it-early-blight-late-blight-or-septoria.htm

As mentioned above, these two types of blight are caused by two different fungi. Early blight is caused by the fungus Alternaria solani and usually appears as tan colored spots with concentric rings on the tomato leaves and also as dark sunken spots on the stem end of the tomatoes themselves. This blight will ultimately turn the leaves and stems yellow as they die. It normally occurs on the bottom of the plants, therefore it can be controlled organically by removing the bottom affected stems and leaves.

Early Blight/Will Also Turn Stems Yellow

Blight can also be controlled by using a copper or sulfur based based fungicidal spray or even a baking soda spray. For more information, refer to the following link: http://www.veggiegardener.com/tips-for-preventing-and-treating-tomato-blights/

Late blight, however, is more likely to kill the entire plant. This blight is caused by the fungus Phytophthora infestans and appears as brown/black spots on the leaves and also fuzzy mold on the underside of the leaves. Unlike the early blight, late blight usually appears on the upper leaves and stems first. This type of blight will affect the entire plant and also the tomatoes themselves. It is recommended that you pull and destroy plants affected by the late blight. It is best to bag them and dispose of them with your trash. Do not place them on your compost pile or rototill them into the garden in the fall.as the fungus can survive the winter.

Late Blight

Blight Prevention Tips:

Try to rotate your crops every year so as not to plant your tomatoes in the same spot every year.
Do not plant tomatoes and potatoes near each other as potatoes can be affected by blight also.
Leave adequate space between tomato plants for better air flow.
Dispose of blight affected leaves/plants. Do not compost them or rototill them into the soil in the fall.
Use a copper or sulfur fungicidal spray or baking soda spray to prevent blight.

Finally some more photos from my garden: