A natural, safe, environmentally friendly treatment for potato blight using horsetail instead of copper sulphate

According to recent news reports, a record 30% of organic potato farmers asked for special permission from the Soil Association to use large amounts of copper sulphate pesticides to prevent potato blight. No one really knows whether this is an eco friendly, safe and sustainable way to treat blight so what is the alternative?

Copper, in small amounts is a necessary trace mineral for human health. It helps the body to utilise iron, maintain normal function of the thyroid gland, maintains the integrity of bones and connective tissue and preserves the myelin sheath that surrounds and protects the nerves. (see Book “The World’s Healthiest Foods, Essential Guide to the Healthiest Way of Eating” by George Mateljan. ISBN 0976918544).

Excessive copper intake can cause abdominal pain and cramps, nausea, diarrhea, vomiting, and liver damage which is why the jury is still out on whether or not the use of copper sulphate in organic farming should be allowed.


From our own experience, the use of copper sulphate is unnecessary. We have used a far more natural and sustainable method to successfully treat blight in the past by using horsetail.

Ok, I’ll admit it. For six years I have tried my hardest to get rid of the horsetail in our garden. But now I’ve learned to love my weed that thrives in our heavy clay soil as it has saved an entire potato crop from the dreaded blight.

Horsetail has powerful antifungal properties that are effective on blight and other fungal infections (in both humans and plants!)


Here’s the recipe we used:

1. In a large glass or stainless steel pot, mix 1/8 cup of dried horsetail leaves in 4 1/2 litres of unchlorinated water

2. Bring to a boil, and simmer for 1/2 hr.

3. Cool, strain, bottle and label. The infusion will keep for a month which is long enough for you to keep reapplying to your crop. Any left overs can be used as a wonderful hair rinse.

4. To use, dilute the 1 part horsetail concentrate to 5-10 parts unchlorinated water. Spray infected plants once every week or two in dry weather or daily if it is raining.


  1. Muppet on March 12, 2008 at 2:00 am

    Now I’m starting to be jealous that I don’t have horsetail in my garden!

  2. Mrs Green on March 23, 2008 at 4:40 pm

    Do you know, Muppet, we have seriously considered whether we could dry the stuff and sell it!

    I’m sure there would be all sorts of red tape over doing this, and of course, no one would actually want it to take root in the garden, but it has other medicinal uses too.

    Like helping with cystitis and other urinary tract infections. It’s also great for skin and hair – full of silica, so can be drunk as a herbal tea. You can even use it as a hair rinse or as a ‘scourer’ to clean saucepans………..

    Great to see you and keep up the good work on your own blog. You’ve had some great offers on there 🙂

    Mrs G x

  3. […] reign. And if you’re worried about potato blight, be sure to read my post about using Horsetail to arrest the development of potato […]

  4. Mandy on November 7, 2012 at 12:36 am

    Thank you so much ! We have a lot of horsetail and now there is a good use for it after the sadness and frustration of losing half our potato crop to blight this year. Thank you, thank you 🙂