Of plums there are three general or common types: first, the common Domestica or European plum, which gives rise to all the older varieties, like Lombard, Bradshaw, Green Gage, the Prunes, the Egg plums, the Damsons, and the like; second, the Japanese plums, which have become popular within the last twenty years, and which are adapted to a wider range of country than the Domestical; third, the native plums of several species or types, which are adapted to the plains, the middle and southern states, and some kinds to the cold North.

Wherever the Domestica and Japanese plums can be grown, the native plums are not destined to become popular; but many of the natives are much hardier than others, and are therefore adapted to regions in which the Domestica and Japanese are not safe. Others of them are well adapted to the middle and southern states. The Domestica and Japanese plums are considerably hardier than peaches, but not so hardy as the apple. The northern limit of their general cultivation is the southern peninsula of Michigan, central and southern Ontario, central New York, and central New England.

Plums thrive on a great variety of soils, but they do better, as a rule, on those that are rather heavy and have a considerable content of clay. In fact, many of the varieties will thrive on clay as hard as that in which pears will grow. On the other hand, they often thrive well in light, and even almost sandy soils.

The trees are set when they are two and three years from the bud. It is preferable to have plum trees on stocks of the same species, but it is not always possible to secure them at the nurseries. In the South, plums are worked mostly on peach roots, and these make excellent trees where the climate is not too severe, and especially on the lighter lands on which they are planted in the South. In the North the larger part of the plum stocks are grown on the Myrobalan plum roots. This Myrobalan is an Old World species of plum, of smaller growth than the Domestica. This stock, therefore, tends to dwarf the tree, and it is also likely to throw up sprouts from the roots.

Plum trees are set 12 to 18 feet apart. Many growers like to set them 8 feet apart in rows, and have the rows from 16 to 20 feet apart.

Plums are pruned much the same as apples and pears. That is, the top is thinned out from year to year, and all superfluous branches and broken or diseased wood are removed. If the soil is very strong and the trees are close together, it may be well to head them in a little each year, especially those varieties which grow very strong and robust.

Pests And Diseases (Pp. 202, 211)

There are four leading difficulties in the growing of plums - leaf-blight, fruit-rot, black-knot, and curculio.

The leaf-blight usually appears about midsummer, the leaves becoming spotted and dropping off. The remedy is to spray thoroughly with bordeaux mixture, beginning soon after the fruits have set, and before the trouble begins to show.

The fruit-rot may be prevented by the same means - that is, by spraying with bordeaux mixture. It is usually best to begin just after the fruits are well set. A very important consideration in the checking of this disease is to thin the fruit so that it does not hang in clusters. If one fruit touches another, the rot spreads from fruit to fruit in spite of the spraying. Some varieties, as Lombard and Abundance, are specially susceptible to this injury.

The black-knot is best kept in check by cutting out the knots whenever they can be seen, and burning them. As soon as the leaves drop, the orchard should be gone over and all knots taken out. Orchards that are thoroughly sprayed with bordeaux mixture for the leaf-blight and fruit-rot fungus are less liable to attacks of black-knot.

The curculio, or the insect which is the parent of the worms in the fruit, is the inveterate enemy of the plum and other stone fruits. The mature beetle lays the eggs in the fruits when they are very small, usually beginning its work about as soon as the flowers fall. These eggs soon hatch, and the little maggot bores into the fruit. Those fruits that are attacked whilst very young ordinarily fall from the tree, but those attacked when they are half or more grown, may adhere to the tree, but remain wormy and gummy at the picking time. The mature beetles are sluggish in the mornings, and are easily jarred from the trees. Taking advantage of this fact, the fruit-grower may jar them on sheets; or, in large orchards, into a large canvas hopper, which is wheeled from tree to tree upon a wheelbarrow-like frame, and under the apex of which is a tin can into which the insects roll. There is a slit or opening in one side of the hopper, which allows the tree to stand nearly in the middle of the canvas. The operator then gives the tree two or three sharp jars with a padded pole or mallet. The edges of the hopper are then quickly shaken with the hands and the insects roll down into the tin receptacle. In this receptacle there is kerosene oil, or it may be emptied from time to time.

Just how long this machine is to be run in the orchard will depend entirely on circumstances. It is advisable to use the catcher soon after the blossoms fall, for the purpose of finding out how abundant the insects are. If a few insects are caught from each tree, there is indication that there are enough of the pests to make serious trouble. If after a few days the insects seem to have disappeared, it will not be necessary to continue the hunt. In some years, especially in those succeeding a very heavy crop, it maybe necessary to run the curculio-catcher every morning for four or five weeks; but, as a rule, it will not be necessary to use it oftener than two or three times a week during that season; and sometimes the season may be shortened by one half. The insects fall most readily when the weather is cool, and it is best, therefore, to get through the whole orchard, if possible, before noon. On cloudy days, however, the insects may be caught all day. A smart man can attend to 300 or 400 full-bearing trees in six hours if the ground has been well rolled or firmed, as it should be before the bugging operation begins.

The same treatment applies to the saving of peaches and rarely, also, of sour cherries.

Varieties Of The Plum

The following varieties of European origin will be found desirable for growing in the northern and eastern states: Bradshaw, Imperial Gage, Lombard, McLaughlin, Pond, Quackenbos, Copper, Jefferson, Italian Prune (Fellenberg), Shropshire, Golden Drop (Cos Golden Drop), Bavay or Reine Claude, Grand Duke, Monarch.

Several of the Japanese varieties are also well adapted to growing in these sections, as well as in the states farther south. The trees are generally hardy, but they bloom early, and are likely to be injured by late frosts in some localities. Among the better kinds are the Red June, Abundance, Chabot, Burbank, and Satsuma.

Few of the above sorts are hardy in the Northwest, and growers there have to rely on varieties of native species. Among these are: Forest Garden, Wyant, De Soto, Rollingstone, Weaver, Quaker, and Hawkeye. Farther south still other classes of plums have been introduced, among them being Wildgoose, Clinton, Moreman, Miner, and Golden Beauty. And still farther south, Transparent, Texas Belle (Paris Belle), Newman, Lone Star, and El Paso are grown.