Late Blight Update July 21 '10

Late Blight on Tomato Plant

Well, it's confirmed...Late Blight report in Waldoboro, Maine. Late Blight affects tomatoes and potatoes. It was the cause for the Great Irish Famine. It is lethal to tomato and potato plants.

Late Blight was a huge issue last summer due to all the rain, moisture, humidity. And it looks like it could be an issue again this year. Last year I lost my entire tomato crop; all 20+ plants and all the tomatoes that were on them. It arrived to my garden mid August, just as tomatoes were really beginning to rippen and I was getting ready for canning. From what I'm hearing Copper Sulfite is the only material available for organic gardeners to use that is effective on Late Blight. BUT....much caution must be used as it is toxic to fish and other aquatic creatures as well as bees and earthworms. So if you've got anything in flower please use this with extreme caution as we do not want to harm bees. Also, follow the container directions to the tea so as not to kill organisms in your soil.

Here's some information for you. Guidelines from Eric Sideman, the pest expert from MOFGA (Maine Organic Farmers and Gardeners Association) - "Copper must be used in a way that does not lead to accumulation in the soil. It is a necessary plant and animal nutrient, but like many other things is dangerous in high amounts. Follow the label, use as infrequently as you can, rotate fields of crops that often get diseases that need the spray so you do not spray the same field often, etc. But, copper is the only effective material available to organic producers if late blight arrives."

Also, here are a few websites with information and photos of Late Blight.
This one is about Late Blight on tomatoes -
http://www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm

And this one is about Late Blight on potatoes: http://www.longislandhort.cornell.edu/vegpath/photos/lateblight_potato.htm

And here's a website with detailed information on Copper Sulfite and the use of it. I highly recommend reading this.
http://extoxnet.orst.edu/pips/coppersu.htm Thanks Arlene for this link!

One last note. If you find you need to remove plant material from your garden that is infected with Late Blight, be sure to bag it up and throw it in the garbage. DO NOT COMPOST PLANTS AFFECTED WITH LATE BLIGHT!

Good luck and let's hope it's not as bad as it was last year. I'm thinking it won't be since we are aware of it and hopefully ready for it.

This is part of gardening..the bad with the good. Still I'd like to repeat...happy gardening; gardening makes the world clean and fresh...even when we deal with issues like late blight.
Mary