Potato Blight and Leek Rust
8th Aug 2007
strong> 8th August 2007
What crazy weather we had during July, I have never seen so much rain in all my life. I built my house 35 years ago and one afternoon during early July, the rain was so heavy that it was within a whisker of coming in through the back door, and our house is nearly on top of a hill!! The humidity that followed the rain has certainly caused havoc and I have never seen potato blight so bad.
A number of growers who came on to my display stand at Hampton Court were all devastated by both Blight on their potatoes and Downey mildew on their onions. The latter is becoming a major problem for the amateur grower as there are is no effective fungicide treatment that can be used. The former however can be controlled, to some extent, by spraying quite regularly with Dithane 945. I have never had the need to spray potatoes in my garden at all as I never had any blight. This year however I was well and truly caught out as were a dozen rows that I had in my field.
Once you have been caught out with the blight there is only one thing you can do and that is to remove the haulms as soon as possible after the leaves show signs of it. To really get the best information available on this I phoned Dr David Shaw from Bangor University who is accepted as a world authority on blight. David’s advice is to remove the haulms and leave the potatoes in the ground for a three week period before lifting them. This will allow the skin on the potatoes to set and prevent any blight spores from entering the potato through any fine scratches into the flesh.
David has been working for a number of years now with the Sarpo family in Czechoslovakia on blight resistant potato varieties and I am certainly going to plant these in my field next year. This year will also be a real test on his varieties to see how well they do stand up against the ravages of this disease. The Sarvari Trust that operates from Bangor, and controls the Blight free potato material, are holding an open day there tomorrow so I am looking forward tremendously to that visit and I shall be writing a report to Garden News about it.
One variety that I was very impressed with was the new trial one called ‘Una’ a new first early that can be ready as soon as eight weeks from planting. It has a lovely pink skin colour with very shallow eyes and may well have some potential for the show bench. It will however be a couple of years before these varieties actually make it on to the market. Currently there are only two blight resiisatnt varieties available from the Sarpo programme Axona and Mira and these are exclusively available from Thompson and Morgan.
There are some good leeks around this year as the weather appears to have been conducive towards a steady even growth under cooler temperatures. You will need to keep your eye out for the Rust disease though that can play havoc with your crop and knock back your chances on the show bench. The rust appears as small red pustules on the older leaves and from there it can really colonise and be devastating. The pustules release thousands of micro spores that can easily move around from plant to plant so the trick is to prevent that happening. A blob of vaseline applied on the rust spot or pustule immediately they are seen will prevent it from spreading further.