INDIANA HORTICULTURAL SOCIETY. 421 



observation was not made on each tree, yet, as a general fact, those 

 which suffered were trees of a full habit and a late growth. 



6. Mr. White, a nurseryman near Mooresville, Ind., in an orchard of 

 from 150 to 200 trees, had not a single case of 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 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 on such a soil as in- 

 sured 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, is lower down, and on old wood. Certainly, 

 it should be, for the returning sap falls some way down before it affects 

 a lodgment. 



8. It might be said that spring frosts might produce this diseasie. 

 But in the spring of 1834, in the last of May, after the forest trees were 

 in full leaf, there came frosts so severe as to cut every leaf, and to this 

 day the dead tops of the beeches attest the power of the frost. But no 

 blight occurred that year in orchard, garden or nm'sery. 



9. It may be aslced 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 their 

 excitability is spent before the 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 frosts in a grow- 

 ing state. I reply first, that we are not to say that every tree or shrub 

 suffers from cold in the same manner. We assert it of fruit trees because 

 it has been observed; it must be asserted of other trees only when it has 

 been ascertained. I reply more particularly that a mere frost is not sup- 

 posed to do injury. The conditions under which blight is supposed to 

 originate are, a growing state of the tree, a sudden freeze, and a sudden 

 thawing. 



We would here add that many things are to be ascertained before this 

 theory can be considered settled, as the afterstate of the sap after con- 

 gelation, ascertained by experiment, the condition of sap vessels as ascer- 

 tained by dissection, whether the congelation, the thawing, or both, pro- 

 duce the mischief; whether the character of the season following the fall 

 injury may not materially modify the malignancy of the disease; seasons 

 that are hot, moist and cloudy, propagating the evil; and others dry and 

 cool, restraining growth and the disease. It is to be hoped that these 

 points will be carefully investigated, not by conjecture, but by scientific 

 processes. 



