440 MANUAL OF GARDENING 
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 Domes- 
tica and Japanese plums are considerably hardier than peaches, but 
not so hardy as the apple. The northern limit of their general cul- 
tivation 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 be- 
coming spotted and dropping off. The remedy is to spray thoroughly 
