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Medwyn Williams

Hello. I'm Medwyn Williams – eleven times Gold medal winner at the Chelsea Flower Show, Past Chairman of the Royal Horticultural Society Fruit Vegetable and Herb Committee and President of the National Vegetable Society.

Horse Manure, New Zealand Flatworms and a visit to Scottish Crop Research Institute, Dundee


Horse manure leads to thinking about worms, which leads to thoughts about the New Zealand Flatworm, plus a visit to the Scottish Crop Research Institute, Dundee

Horse Manure for the Celery Bed

One task that I shall be getting on with quite soon is my annual trip to a farmer friend of mine for some manure, the manure that I shall get is horse manure and seems to do really well in my celery beds. It will be few years old as he has a huge pile of it and one of the best sights that I can have is to see those red worms working their way through it. In time these will of course work their way into my soil and thereby, through natures own process, the organic content of my celery beds will be raised as will the humus content.

New Zealand Flatworms

Whilst thinking about worms my mind went back a couple of years ago to gardening programmes and gardening magazines that were all doom and gloom regarding the invasion of the New Zealand flatworm. After that initial period I never heard no more about it and I really thought that the whole matter had either been well over hyped or that the problem had just, either been controlled or was never any danger in the first place anyway.

On my recent trip to Dundee for the National Vegetable Society Championships I visited the Scottish Crop Research Institute stand and was quite alarmed to hear that not only was the flatworm still around, it was spreading. More alarmingly was the fact that from the original New Zealand flatworm Arthurdendyus triangulatus that first recorded in Scotland during 1965, we now have 3 more species. These three new species were discovered in the last five years and are as follows: Australian flatworm Austroplana sanguinea first recorded in 1995, Edinburgh flatworm Arthurdendyus albidus first recorded in 1996 and described in 1999; the third is Arthurdendyus australis first recorded in 1997.

Surveys carried out for the Scottish Office Agriculture and Fisheries Department and Tomorrow’s World, showed that it initially spread only slowly and was mainly found in Botanic gardens, nurseries and garden centres. However by 1994 it was usually found in domestic gardens and is now recorded from most of Scotland including the islands of Skye, Coll, Islay, Orkney, Shetland and Lewis. Since then the percentage of garden centres infested has decreased and now the New Zealand worm is probably mainly spread by the exchange of containerised plants between neighbours, relatives and friends.

The reason for my concern with this particualr flatworm is because it is a predator of our earthworms which keeps our soils in good condition as well as being a source of food for lots of animals and birds. They have been known to reduce earthworms to below detectable levels. The New Zealand flatworm likes cool damp conditions and reproduces by laying an egg capsule which usually has inside it 6 to 7 creamy coloured ‘hatchings’. It probably feeds at night on the soil surface where it catches the earthworms and digests them externally and then sucks up the resulting ‘soup”. During the day the new Zealand flatworm hides under polythene bags, bits of wood or stones and that is the best place to look for them.

Do keep your eyes open for these as I certainly don’t want to see them in my garden, they are quite distinctive because as the name implies, they are quite flat in shape and quite different from the round friendly earthworm.

Reporting New Zealand Flatworms

If you see any of these flatworms then you could help towards the research work that is going on into these aliens by contacting Mr Brian Boag at the Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA or telephone on 01382 562 731.


Also at the Dundee show, daily Seminars were organised jointly by the RHS and the NVS; one of the speakers there was Dr Jack Dunnett B.Sc.(Agric.) Ph.D, M.I.Biol., F.R.Ag.S. from Caithness. Whilst at the seminar he introduced his new book called A Scottish Potato Breeders Harvest which is about his lifetime work in breeding new and exciting varieties of potatoes. Undoubtedly Dr Dunnett has become a legend in his own lifetime within the potato world having introduced varieties that will surely be with us for many years to come. To list just a few of the most popular varieties: Nadine, Stroma, Winston, Kestrel Swift, Celine, Maxine, Osprey, Harmony, all of these when well grown would win at any level. Indeed during his talk that day he mentioned that five of the six dishes staged in the World Potato Championships and three of the four dishes in the Scottish Potato Championships were of his own breeding.

The book is certainly compelling reading to anyone who has an interest in breeding potatoes and covers a lifetime of work, 46 years in total, and the first paper in the book is a text of the first lecture he gave as a private potato breeder some fifteen years ago.

The book is available from Thompson and Morgan, Poplar Lane, Ipswich. IP8 3BU and the price is £24.00 inclusive of post and packing.

Tomato Question

Duringa question and answer session at the above show a question was raised regarding the bronzy colour that one grower had coming through on the skin of his tomatoes. No one seemed to have the right answer for this one, after the event I had a letter from Robert Foster from Mansfield who had experienced this phenomenon and he says that the bronzing is part of a range of skin discoloration”s attributed to tomato mosaic virus; the colouring is brought about by necrotic (dying) cells.

Tomato mosaic virus is the main cause of these symptoms, but poor growing conditions such as incorrect temperatures, poor light, excessive watering and nutrient levels can increase the chances of this problem occurring. Choosing tomatoes that have a tolerance to tomato mosaic virus will go a long way to avoid the problem.

I just hope that the gentleman who raised the question at the seminar will appreciate this reply.


Growing Parsnips

25th July 2007 I am often asked what is the best method of growing both long carrots and parsnips for the show

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