This year, it wasn't too bad. The previous two years were quite bad. The year before that was awful. What is it? Tomato and potato blight - the scourge of veg growers.
OK, we have blight-resistant varieties - the Sarpos, for instance. But I like to grow the varieties I like to eat.
Years ago, when blight was bad, I was happy to spray plants with Dithane and the control was excellent. Then that got taken off the market and so this year I used Bayer Garden Fruit & Vegetable Disease Control with good results. Then horror of all horrors, I read in Which? Gardening that copper-based fungicides are being withdrawn. Cheshunt Compound (which contains copper sulphate) is no longer available to buy from November 30, 2010 and any existing tins must be used up by November 30, 2011 or disposed of safely. The report goes on to say: ”Other products containing copper sulphate, copper oxychloride...are also being withdrawn. Bordeaux mixture, which contains copper sulphate, is currently approved for use until the end of 2013." Bayer Garden Fruit & Vegetable Disease Control contains copper oxychloride. So, I did some checking around - including the PSD website - and also got this information: "Bayer is going to continue to support Fruit & Vegetable Disease Control and so it will go on beyond 2012/2013." So I'm happy.
There were some reports in the summer about genetically-modified resistance to potato blight and then I saw this today on the Horticulture Week website (www.hortweek.com): Researchers from the University of Dundee, the Scottish Crop Research Institute examined the behaviour of Phytophtora infestans and how it interacts with potato plants, and identifying the proteins secreted by the pathogen that play an essential role in infecting the plants. The researchers now know a lot more about how P. infestans gets round the potato plant's natural defences and what it takes for the plant to resist infection. They can now look at a potato plant's genetic make-up and say whether it will be sustainably resistant to late blight. All good news.
The other weapon in my blight arsenal is the Blight Watch website (www.blightwatch.co.uk) where you can put in your postcode and get a warning when blight is forecast in your area. All very clever.
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