Irises And Disease

The Gardeners’ Chronicle, p.248, June 15, 1918

Irises and Disease. -Even at the risk of incurring the title of " faddist," which Mr. Watson bestows on those who transplant rhizomatous Irises in summer, I cannot let his remarks, on p. 233, pass unchallenged. It has probably been my lot to plant and replant as many kinds of Irises in the last ten or fifteen years as most gardeners deal with in a much longer period, and I doubt very much whether it is really " so utterly opposed to nature to dig up rhizomatous Irises when in full leaf " as Mr. Watson appears to imagine. If he will dig up a plant that is just going out of flower he will find that the roots attached to the main axis which ends in the flowering stem are brown and withering. Obviously they have done their work in nourishing the stems and the flowers. It is to the lateral growths that we must look for flowers in the following year, and here he will find that root-growth is beginning. There may be young, unbranched fibres a few inches in length, and, besides, there are sure to be a number of points of new roots just pushing out from the rhizome. Surely, then, this is the moment at which transplantation may be carried out without detriment to the plant. Mr. Watson does not tell us when he would transplant such Irises, but presumably he would do it in the autumn or in the early spring. In the former case, root-growth has ceased for the year, and the plants lie in the ground through the winter without taking hold of it, and are often actually lifted out of the soil by frost and thaw, while in the latter case the flowers for the coming season are either entirely sacrificed or at least stunted. I wish Mr. Watson could have seen my garden a week or two ago. There were many beds of Irises in full flower, although all the plants in them were transplanted in June, July and August last year. On the other hand, there were a few in which the Irises had had to be planted later. In these the plants were stunted and the flower-stems few. For the disease from which apparently the Kew collection is suffering there is a very simple remedy, namely, superphosphate of lime. I must confess that my garden is never entirely free from traces of this disease, but, on the other hand, I think I can truthfully say that it has never yet carried off all my plants of any variety or species. I seem to recollect that I was once told that, when the disease first appeared at Kew, the beds were dressed with lime. If this is so, it is hardly surprising that no cure was effected, for once the bacillus that does the harm is present, it is an acid reagent, such as superphosphate, and not the neutralising lime, that is required to destroy it. When leaves turn yellow and rhizomes rot, usually at the neck, level with the ground, the diseased portions should be pulled or cut out and superphosphate sprinkled liberally all round and watered in. Within the narrow limits of my garden I am unable to give my plants fresh soil as often as I should like to do, but it has become mv practice always to dress the surface fairly liberally with superphosphate whenever Irises are being transplanted, and so far. at any rate, my collection has not suffered to any appreciable extent.

W. R. Dykes, Charterhouse, Godalming.

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-- BobPries - 2014-06-19