Wednesday, August 12, 2009

Late Blight, Continued

Right before I took off for Oklahoma for the 4th of July family gathering, I posted about late blight of tomatoes and potatoes having become a huge problem in the Northeast. My garden seemed okay, and I hadn’t heard any more about it in the news, so I quit thinking about it.

However, I’ve been reading garden blogs from other parts of the country, and it turns out that late blight is very widespread, killing plants all across the Northeast, East, and Southeast. After reading several posts by frustrated gardeners, I looked around online and found that late blight has been found in Georgia.

The Master Gardener blog for the Western North Carolina mountains posted on July 21st that late blight had been identified in a commercial field near Dillard, GA, in the northeast tip of the state.

They recommend that growers/gardeners read this webpage from North Carolina State University’s Plant Pathology Department to learn more about the disease, which can, apparently, wipe out a whole field of plants in a week or less. If your plants have late blight, this is what you’ll see:

“The pathogen attacks all aboveground parts of the tomato plant. The first symptoms of late blight on tomato leaves are irregularly shaped, water-soaked lesions (Figure 1); these lesions are typically found on the younger, more succulent leaves in the top portion of the plant canopy. During humid conditions, white cottony growth may be visible on the underside of affected leaves (Figure 2). As the disease progresses, lesions enlarge causing leaves to brown, shrivel and die (Figure 3). Late blight can also attack tomato fruit in all stages of development. Rotted fruit are typically firm with greasy spots that eventually become leathery and chocolate brown in color (Figure 4); these spots can enlarge to the point of encompassing the entire fruit.”

It is thought that the late blight is so widespread and early this year because it was introduced across the entire Eastern US on infected transplants from Bonnie Plants.

Interestingly, this 28 July ’09 article seems to indicate that the source of the late blight infection in Bonnie Plants was its “facilities in Georgia”!

I have been longing for rain here, and my yard did get a half inch this afternoon, but mostly it has been hot and dry for several weeks. Since late blight thrives in cool, damp conditions, maybe I should be a little happier with our current weather!

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