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Rust (Cystopus candidus and Mildew)

(Cystopus candidus) and Mildew (Peronospora parasitica). The former produces white patches on the leaves, and also grows on and deforms the flowers, causing an enlargement of all their parts, and rendering them sterile (see Rusts). The Mildew (see Peronospora) is much less noticeable in its effects, but is not less hurtful to the plants.

INSECTS. Radishes are apt to suffer from the ravages of the same insects as feed on Turnips. Roots of Radishes are eaten by the usual subterranean foes that attack other fleshy roots. Among these are Julus and other Millipedes (which see), and the larvae of certain Noctuae, or Night Moths. The most dangerous of the foes that live on the roots are the larvae of several species of flies that belong to the same genus as the Onion Fly (which see). All of these larvae eat the roots of other Cruciferae, also, e.g., Cabbage; but one species (Anthomyia radicum) has received the name of Radish Fly, from its preference for this plant. This fly is very common throughout the summer. Its body is about 1/5in. long, and its spread of wings from 1/3in. to 1/2in. The body is covered, not very thickly, with stiff hairs. The male has the thorax black, with two short, grey, narrow stripes lengthwise; the abdomen is grey, with a black line down the middle and three black lines across it; the forehead is white, with a black, triangular spot; the face is whitish-ochreous; the legs and antennae are black; the wings are transparent, and the third and fourth veins in each converge slightly. The female differs from the male in the broader body, and the ash-grey colour; the stripes on the thorax are faint-coloured, and there is only a slender, dark line down the middle of the abdomen. The larvae have neither head nor limbs, but are blunt behind, and taper to a point in front. They are yellowish, fleshy, and wrinkle. On the blunt hinder end are several fleshy lobes, and breathing-pores in two groups of three each. The larvae eat into the roots, and cause them to rot. When full-fed, they leave the roots, and change, in the soil, into dull ochreous pupae of the form usually met with in Diptera. The larvae of Anthomyia floccosa, Macq. (? A. floralis, Fall.), also feed in the roots of Radishes, Cabbages, and allied plants, as do likewise the larvae of A. Brassicae (see Cabbage Fly) and of A. (Homalomyia) canicularis; and those of A. Raphani feed on Radishes in North America. All of these insects are very like the Radish Fly, and it is unnecessary to describe them, since the habits of all are much the same in all stages. The larvae have been found in large numbers feeding in dung, and the insects have been reared from this. It has also been observed that when ground is manured with farmyard dung, the root-crops are apt to suffer from the attacks of larvae of these flies. Remedies. The most effectual seems to be crude carbolic acid, in solution. Successful results have followed its use, in the strength of half a pint of acid mixed with one gallon of boiling water, to which about a quart of soft soap has been added. This should be diluted with fifty gallons of water; or it may be used even in a weaker solution. The plants should be watered with this fluid every week, after they appear above ground. Instead of this, much-diluted gas-water may be used; or gas-lime may be sprinkled along the rows. Farmyard manure is not safe, if there are maggots in it; mineral manures may be substituted in their stead.

Radish leaves are occasionally eaten by larvae of the White Butterflies (Cabbage Caterpillars), and of various Moths (Mamestra, Plusia, Potherb Moths), as well as by the Turnip Flea (Phyllotreta nemorum), and by other small beetles allied to it. The seeds are destroyed in the fruits by larvae of Ceuthorhynchus assimilis (Turnip-seed Weevil), which is closely allied to the Weevils that make galls on roots of Cabbage, Turnip, Charlock, and Wild Mustard. For the nature of the injuries in each case, and for the appropriate remedies, see the heading quoted for each.

SORTS. Of these there are many in commerce which may be classed as Long-rooted and Turnip-rooted varieties. There are also intermediate globular forms, and these are much esteemed. The following varieties are amongst the best: BLACK SPANISH, an excellent hardy sort for autumn and winter use. CHINA ROSE, root oblong or somewhat conical, bright rose-coloured; also a fine variety for autumn and winter . EARLY FRAME (Wood's), one of the earliest, shorter than the LONG SCARLET, of which it is a sub-variety; fine for forcing. EARLY ROSE GLOBE, a very early and much-esteemed sort, of a fine, clear rosy-scarlet, compact FRENCH BREAKFAST, a beautiful olive-shaped variety, with white tip, of quick growth, and very mild flavour; one of the best for forcing and summer use. LONG SCARLET, SHORT-TOP, one of the best and most esteemed long varieties, because of its bright colour; much cultivated for market. OLIVE SCARLET, an excellent sort, of quick growth and fine colour. RED TURNIP-ROOTED, crisp, and of mild flavour; very extensively grown for market, and well adapted for general summer use, because it withstands dry weather. WHITE TURNIP-ROOTED has a white skin, but otherwise differs very little from the red variety; it is equally good, but the colour of the latter is generally preferred.