It is beyond doubt true that we have in the United States the largest and best native wild blackberries of the north temperate zone and probably of the world. The cultivated varieties are all selections of best varieties found in a state of nature, and, so far as known to the writer, the blackberry is not grown commercially in any part of the world except the United States and Russia, and the Russian varieties grown on the Volga River bluffs are not equal in size or quality to our best varieties. The varieties cultivated belong, in different sections of the States, to several quite distinct types or species. But the horticulturists describe the habit of growth and style of cluster and fruit without much regard to botanic distinctions. Four main types are recognized by close-observing growers: (1. Seedling Variations) The high bush of clearings and fence rows of the Northern States with long clusters, such as those of the Ancient Briton. (2. Seed Variation of Cultivated Plants) The type with lower growth and short clusters, such as those of the Snyder and Kittatinny. (3. Commercial Seeds) The hybrid class between the blackberry and dewberry, represented by Wilson and Rathbun. (4. Seed-saving) The trailing dewberries, such as Lucretia, Mayes, and Windom.
The readiness of all these classes to cross naturally when adjoining shows that they are very nearly allied. In the prairie States, even, all the types of the dewberry and blackberry will, when adjoining, cross naturally and almost invariably, as shown, when the grower or birds have planted the seeds, which is not usual with distinct and well-defined species.
When the dewberry and blackberry are crossed the resulting seedlings bear perfect seeds, which is another indication that they are nearly allied.
The blackberry and raspberry are nearly allied botanically and require about the same treatment and the same methods of propagation as the red raspberry. At the North it requires laying down for winter protection of canes and fruit-buds (249. Raspberry Winter Protection).
Neat and methodic amateurs grow the plants in stools, as with the red raspberries, but commercial growers by pinching (247. Pruning the Raspberry) develop stocky plants which are grown in narrow matted rows. With this plant care is needed in the spring to destroy the weaker shoots and only to permit the strongest to form canes for the next year's fruiting.
In the spring-pruning the work is deferred until the blossom-bads begin to appear, as these buds are often near the ends of the young canes. Some seasons cutting back the tops will destroy all the fruit-buds nearly. But taking out of the old wood must be done in the fall, where laying down is practised. In taking out the canes that have fruited, an implement is used with a handle five feet long, as shown in Fig. 79.
Fig. 79. - Tool for taking out the old canes that have borne fruit one season.