4. Trees which ripen their wood and leaves early, are seldom affected. This ought to elicit careful observation; for, if found true, it will be an important element in determining the value of varieties of the pear in the middle and
western States, where the late and warm autumns render orchards more liable to winter blight than New England orchards. An Orange Bergamot, grafted upon an apple stock, had about run out; it made a small and feeble growth, and cast its leaves in the summer of 1843, long before frost. It escaped the blight entirely; while young trees, and of the same kind (we believe), standing about it, and growing vigorously till the freeze, perished the next season. I have before me a list of more than fifty varieties, growing in the orchard of Aaron Alldredge, of Indianapolis, and their history since 1836; and so far as it can be ascertained, late-growing varieties are the ones, in every case, subject to blight; and of those which have always escaped, the most part are known to ripen leaf and wood early.
5. Wherever artificial causes have either produced or prevented a growth so late as to be overtaken by a freeze, blight has, respectively, been felt or avoided. Out of 200 pear-trees, only four escaped in 1832, in the orchard of Mr. Reagan. These four had, the previous spring, been transplanted, and had made little or no growth during summer or fall. If, however, they had recovered themselves, during the summer, so as to grow in the autumn, transplanting would have had just the other effect; as was the case in a row of pear-trees, transplanted by Mr. Alldredge in 1843. They stood still through the summer and made growth in the fall—were frozen—and in 1844 manifested severe blight. Mr. Alldredge’s orchard affords another instructive fact. Having a row of the St. Michael pear (of which any cultivator might have been proud), standing close by his stable, he was accustomed, in the summer of 1843, to throw out, now and then, manure about them, to force their growth. Under this stimulus they were making excessive growth when winter-struck. Of all his orchard, they suffered, the ensuing summer, the most severely. Of twenty-two trees twelve were affected by the blight, and eight entirely killed. Of seventeen trees of the Bell pear,
eleven suffered, but none were killed. All in this region know the vigorous habit of this tree. Of eight Crassane Bergamot (a late grower), five were affected and two killed. In an orchard of 325 trees of 79 varieties, one in seven blighted, 25 were totally destroyed. Although a minute observation was not made on each tree, yet, as a general fact, those which suffered were trees of a full habit and of a late growth.
6. Mr. White, a nurseryman near Mooresville, Morgan County, Indiana, in an orchard of from 150 to 200 trees, had not a single case of the blight in the year 1844, though all around him its ravages were felt. What were the facts in this case? His orchard is planted on a mound-like piece of ground; is high, of a sandy, gravelly soil: earlier by a week than nursery soils in this county; and in the summer of 1843 his trees grew through the summer; wound up and shed their leaves early in the fall, and during the warm spell made no second growth. The orchard, then, that escaped, was one on such a soil as insured an early growth, so that the winter fell upon ripened wood.
7. It may be objected, that if the blight began in the new and growing wood, it would appear there; whereas the seat of the evil, i. e. the place where the bark is diseased or dead, is lower down and on old wood. Certainly, it should be; for the returning sap falls some ways down before it effects a lodgment.
8. It might be said that spring-frosts might produce this disease. But in the spring of 1834, in the last of May, after the forest-trees were in full leaf; there came frost so severe as to cut every leaf; and to this day the dead tops of the beech attest the power of the frost. But no blight occurred that year in orchard, garden or nursery.
9. It may be asked why forest-trees do not suffer. To some extent they do. But usually the dense shade preserves the moisture of the soil, and favors an equal growth during the spring and summer; so that the excitability of
the tree is spent before autumn, and it is going to rest when frost strikes it.
10. It may be inquired why fall-growing shrubs are not always blighted, since many kinds are invariably caught by the frost in a growing state.