368. Black Rot (Pseudomonas Campestris)

This bacterial rot is very generally disseminated, frequently spreading over large areas in cabbage-growing districts, and causing heavy losses. The disease also affects cauliflower, kohl-rabi, kale, brussels sprouts, broccoli, collard, turnip, radish and cruciferous weeds. Its development in a plant is noted by decided yellowing, followed by dying of all affected parts of the leaf, the margins having a burnt appearance; the veins become brown or black and dark rings are observed in the stump. When leaves are removed at the stump, the fibro-vascular bundles appear as small black spots on the leaf scars. If badly infected the plant is dwarfed or makes a one-sided growth and often fails to mature. On account of black streaks, the heads are unsalable and frequently rot and fall off before a marketable size has been attained.

Infection occurs through tiny drops of water on the margins of the leaves, through wounds caused by tillage or insect attacks and through the roots. Experiments at the Geneva station show that pulling and destroying the diseased leaves is not satisfactory. By this radical treatment the yield was reduced 3« to 5¬ tons an acre as compared with undisturbed plants.

Infection may occur from the use of seed contaminated with the germs. To avoid trouble from this source, the seed should be soaked 15 minutes in formalin solution, made by dissolving one pound of formalin in 30 gallons of water. Other preventive measures are rotation, the destruction of cruciferous weeds and insect enemies, and the use of soils and manures free from the disease germs.

369. Other Diseases

Although club root and black rot are the most important diseases of the cabbage, the following cause more or less trouble: Leaf-spot (Sphae-rella brassicaecola); stem canker and drop (Phoma oler-acea); mildew (Peronospora parasitica); a dark rot (Sclo-tinia libertiana), studied by the Missouri Botanical Garden ; a bacterial soft rot closely related to Bacillus caro-tovorus; root rot or stem rot (Corticium vagum); and white rust (Cystopus candidus).

370. Sauerkraut

It is often desirable to make kraut when the market is weak, or when there is a considerable quantity of soft and burst cabbage. The process is very simple. After removing the cores and outside leaves, the heads are sliced or shredded by special devices or machines. The finely cut cabbage is then placed in barrels in successive layers of about 6 inches, salted slightly and pounded. This operation is repeated until the barrel is nearly full. About one pint of salt is required for a barrel of kraut. The cabbage is then covered with a cloth, and boards cut to fit loosely in the barrel are heavily weighted. The brine formed by the salt and the juice should cover the cabbage during the acetous fermentation.

In one of the large kraut factories, the cleaned and cored cabbage is placed in conveyors which carry it to the shredders. The cut cabbage is then conveyed to the upper floor of the plant, where it is properly salted, and then dumped into a long chute which delivers it in large tanks on the first floor, to be mixed and packed. The stamping and packing is done by men with new rubber boots. The time required for curing depends largely upon the weather, but it usually takes from two weeks to a month. While in the tanks the cabbage must be watched carefully to see that it is kept under the brine. When fermentation is thought to be complete samples are secured for testing from the interior of the tank by means of a long wire hook. The kraut is then removed and packed in cans, kegs and barrels. No vinegar or other foreign substance is used in this factory to sour the cabbage.