SLEEPY DISEASE, or TOMATO WILT.—In its outward symptoms and effects this disease somewhat resembles an attack of Root-knot Eelworm, but the swellings are absent from the root. The plants for a time appear quite vigorous and healthy, but when full-grown they suddenly wilt and die within a few days. The malady is caused by the fungus Fusarium lycopersici, which first invades the roots and ultimately eats its way through the substance of the collar or stem near the surface of the soil, in consequence of which the supply of water taken up by the roots is cut off from the leaves above ground and the plant collapses. There is no remedy for the Sleepy Disease of Tomato, and plants which bear evidence of infection should be carefully dug up and burned.
TOMATO ‘STRIPE.’—This disease of the Tomato is comparatively common, and although the attacks are sometimes slight its ravages may be disastrous when conditions are favourable for its development. The presence of Tomato Stripe is usually first noticed about the time fruit is forming. The stems of the diseased plants then exhibit dark spots and elongated sunken stripes of a brown tint, and yellow patches, which turn brown later, appear on the leaves. Brown pits or depressions develop on the fruits and spoil their appearance. The disease has been traced to the action of a bacterium which closely resembles, or is identical with, that causing Stripe among Sweet Peas. This organism probably resides in the soil, and the signs of its attack are often visible in young plants. In severe cases the soil of the house should be removed and replaced with fresh loam. But when only slight traces of the disease are apparent, partial sterilisation of the soil by means of carbolic acid, as recommended for Root-knot Eelworm on page 425, may be adopted. One of the surest means of guarding against losses by Stripe disease, is to promote robust healthy growth, and to avoid extreme forcing conditions, particularly by the excessive use of nitrogenous manures. Where, however, forcing manures may have been employed in too large a quantity, an application of potash (in the form of kainit or sulphate of potash) and phosphatic fertilisers should be given to counteract the effect of the nitrogen. Immediately any trace of the disease is found, remove the affected part of the plant, if it is possible to do so without serious injury, but otherwise the entire plant should be uprooted and destroyed by fire. It should be remembered that the organism can be carried on the fingers and on tools, and therefore knives with which affected plants have been trimmed should be sterilised with lysol or some other antiseptic solution before being used on healthy plants.
TOMATO-LEAF RUST.—The leaves of the plant attacked by this disease rapidly become covered with a dull brownish velvety mould, or fungus, known as Cladosporium fulvum. From the mouldy spots and patches thousands of spores are readily carried by a slight current of air to the surrounding healthy crop, and unless prompt measures are taken to check the pest the whole house is rapidly involved. Excessive atmospheric moisture encourages the mould, and it is spread extensively if diseased plants are sprayed with water in the presence of healthy ones. Judicious management in air-giving, which is one of the fundamental principles of successful Tomato culture, will do much to prevent the attack of Cladosporium fulvum. Under regular examination the presence of the disease will be revealed before considerable damage can be inflicted, and when only a few leaves are affected, carefully remove and consign them to the fire. Spraying with the Bordeaux mixture at half the usual strength is recommended when the disease is first noticed. When the plants are bearing flowers or fruit, fungicides containing copper must not be used, but a solution of liver of sulphur, one ounce dissolved in six gallons of water, employed instead.
ROOT-KNOT EELWORM.—A dangerous insect pest which frequently attacks the Tomato, in common with the Cucumber and Melon, is the Root-knot Eelworm (Heterodera radicicola). The root on which the swollen pea-like knots develop do not carry on their ordinary functions, and the leaves droop, the stem becomes limp, and the whole plant soon collapses and dies if the trouble is severe. The treatment suggested on page 425 should be adopted.
Sometimes the outdoor Tomato crop is attacked by Phytophthora infestans, the fungus responsible for the Potato Disease: Bordeaux mixture should be used to check it.
Directions for preparing the Bordeaux mixture are given on page 440.
Another useful preparation which checks many fungus diseases may be made by dissolving one ounce of potassium sulphide (liver of sulphur) in three or four gallons of water, to which should be added an ounce or two of soft soap. The last named greatly assists in the complete and uniform wetting of all parts of the foliage.
THE FUNGUS PESTS OF CERTAIN FLOWERS
Cineraria and Senecio Disease.—Senecio pulcher, soon after its introduction into England, was attacked, and in some gardens completely destroyed, by a fungus named Puccinia glomerata, or rather the Uredo stage of this fungus with simple, not compound, spores. The fungus is well known, being closely allied to that which causes the rust or mildew of corn crops. It is very common on the wild species of Groundsel in England, being especially frequent and virulent on the Ragwort Groundsel, Senecio Jacobea, from August to October. The leaves of infected plants are covered with rust-coloured dusty pustules, the Uredo condition of the fungus, and known in this stage as Uredo senecionis, sometimes termed Trichobasis senecionis. The fungus has a Puccinia stage of growth very similar to that of the Hollyhock fungus, Puccinia malvacearum.