CUCUMBER (Cacumis sativus and its con geners), an annual trailing or climbing vine of the natural order Cucurbitacem, cultivated for its unripe fruits which are used as a salad and for making pickles. The plant is a native of southern Asia where it has been cultivated since early historic time. The vine is more or less prickly, bears three lobed or angled leaves which closely re semble those of the muskmelon, and generally spiny fruits which may become smooth as they mature. The fruits are solid and contain numer ous boat-shaped flattened seeds embedded in a somewhat watery pulp, which in the imma ture fruits is the part esteemed. Small-fruited varieties and little fruits of large varieties are popularly known as gherkins and are generally preferred for pickles. They are covered with strong brine until needed for use, when, after soaking in pure water to remove the salt, they are put in vinegar, which they soon absorb. There is a !Feat range in size of fruits in the various varieties, some being only about two inches long, and others more than 12 inches by 3 in diameter. Perhaps the most popular group of varieties is the white spine.
Cucumbers thrive best in warm soils well exposed to the sun. They do not produce well upon heavy clays or very light sands. The land must be well drained, in good tilth and fairly rich. For earliest crop the seeds are often sown in •otheds on inverted sods, and the plants set in the field as soon as danger of frost has passed, a sowing of seed being made about the same time to serve as a second crop. Usually only two or three plants are allowed to remain in the hills which are made about four by six feet apart. Since the cucumber-beetle is very actively destructive while the plants are small, six or tight plants should he allowed to remain in the hills until the vines are able to resist attack. Cultivation should he very thor ough until the plants begin to run, when it should be confined to the space not occupied by vines. Often, in making the hills, a forkful of well-rotted manure is mixed with the soil to give the plants a little start.
Of the numerous diseases that attack the plants the one usually seen earliest in the season is damping-off (Pythium debaryanum) which appears while the seedlings are small. plants quickly become yellow, and wilt and die. It may be prevented by early spraying with a standard fungicide (q.v.) which should be ap plied to the whole hill and to the under sides of the leaves. Wilt disease caused by Bacillus tracheiphilus is an internal trouble that cannot be combated. The bacteria are spread by in
sects which inoculate healthy vines by biting or puncturing them. The bacteria multiply in the water-vessels of the vines and impede or stop the flow of water, the leaves wilt and finally shrivel, and the plant dies. It is believed that prevention of the attacks of insects by covering the plants with wire netting until they begin to run will postpone the time of the attack of the bacillus, so that a partial crop may be ob tained. Usually the vines die just before the crop is ready to gather, the whole field being attacked. In greenhouses the most common disease is powdery mildew (Erysiphe cicho racearum). It appears as white patches on the leaves which become yellow, brown, then die. Often the whole plant is involved. Evaporated (not burned) sulphur and spraying as above will control this pest.
The most important insect enemies of the cucumber are the cucumber-beetles (Diabrotica) and the squash-bug (Anasa tristis). The beetles are striped or spotted yellow and black, or green and black, are about a third of an inch long, very active in taking flight, and feed mostly upon the under sides of the leaves and the soft stems of seedlings. The larva burrow in the roots, and if numerous, they often kill the plants. During the heat of the day the adults generally hide below the surface of the hill. A liberal use of tobacco-dust upon the hills as soon as the plants peep through the soil is the popular remedy. But since remedies are not entirely satisfactory, the plants are fre quently covered with netting until they are about to begin running.
The squash-bug is a dull-gray insect about three-quarters of an inch long. It sucks the juices of the plants. There is no known satis factory remedy for it, but the destruction of the vines as soon as they have fruited or plow ing them under is helpful toward its extermi nation. Hand-picking is sometimes resorted to, as is also the destruction of the eggs, which are conspicuously laid on the under sides of the leaves. The cucumber is frequently grown in greenhouses, especially in- spring after the main winter crops are out. The plants are started in pots, transplanted to the benches when well established, trained on trellises close to the roof, kept at a rather high temperature, and allowed to suffer no check. The white-spine class is most popular for this purpose in Amer ica, but the long English forcing varieties are by many considered superior in quality.