CARNATION RUST

Evening Star, Issue 22572, 13 February 1937, Page 24

CARNATION RUST

A HEW CURE Judging by the innumerable complaints received during recent seasons there can bo little douot that the rust of carnations is on the increase (writes the Auckland ‘ Herald’s ’ gardening contributor). In spite of all the various remedies which check its ravages temporarily there has until lately been no material or method which has kept the plant immune. Fortunately, however, there now seems to be hope of not only curing the disease, but preventing it, a very much more important issue. Lime as every gardener knows, is essential to carnation culture, but calcium oxide is not the only form of it. Neither has it the properties suitable for all soil conditions or the ability to mingle with it and thus render it akin to the original habitat of the dianthus family, which was dry nnd in most cases in steep, perfectly-drained, rocky areas. The carnation as a florist’s flower has been subjected more and more to conditions totally at variance with these simple needs in! order to obtain the largo blooms demanded not only for exhibition, but for ordinary garden purposes. The necessary, though sometimes excessive, fertilisation of the soil, either by organic or chemical means, or, both, is probably the chief source of disease and delicacy of constitution, leading to early decay and ultimate death of the plant. It is over 60 years since rust was first noticed, but, whatever the cause, its severity has meant the destruction of thousands of plants.. In the open ground, even in bad cases, the liberal use of well-weathered soot, dusted over the plants after they have been sprayed with a solution of one tablespoon of common salt to two gallons of water, will effect a cure. Two applications may be required, but it is not necessary to cut off any of the leaves, as the disease spores will dry up and disappear with this treatment. Under glass, however, it is not possible to use soot—except in extreme cases —to the extent that may be necessary as an overhead dust, although it is being used more and more as a topdressing at planting time. In the latter case it is thinly covered with compost. Very finely-ground carbonate of lime has come to be recognised as a great deterrent to disease. Rusty plants can be sprayed with the salt solution and then thickly dusted with the powdered limestone, which is left on to dry. This cures the disease and destroys the spores in a few weeks as a rule. Soot is only resorted to in obstinate cases, when a second application is necessary, the plant again being sprayed over as. before.