STATE HORTICULTURAL SOCIETY. 151 



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US refer to a simple jilitMionienoii tlmt is well known. Tf a paste of 

 flour and water be allowed to freeze, it seems to be very different af- 

 ter freezin<if fron) what it was before. At first it was a homogeneous 

 mass, but, after freezing, it seems to be formed into little masses 

 with part of the water separated and standing in little pools, in oth- 

 er words, a change has taken place in the whole niass. A change 

 something like this takes place in these gorged cells as they freeze, 

 so that the life-giving principles no longer absorb this water and ex- 

 ert their intln(Mue as life forces, but are henceforth dead matter. 

 Freezing may, also, burst the cells. The following s])ring may be 

 ever so balmy, this part of the tree cannot be called into activity in 

 carrying the gathered stores to the leaves for digestion, nor aid in 

 the assimilation of the returning current. The fact of the flow of 

 sap, under circumstances as here given, may be verified by cutting a 

 chip out the southwest side of a maple tree whose trunk is fully ex- 

 posed to the sun. It the bark of such an ap]ile tree, as we have been 

 considering, be cut into the following summer, instead of a healthy 

 looking inner surface, and the projjcr smell of the growing tree, the 

 parts will appear darkened and the sap will smell sour. Later, the 

 outer bark will become blackened, and failing to expandwith the 

 growth of the tree next year, will crack and, after a time, fall off. 

 This dead and cracking bark forms iin excellent place for borers to 

 find an entrance to the tree, hence, it is seldom that advanced stage 

 of sun blight is found without the presence of the flat-headed apple 

 tree borers who enlarge the deadened place and help to carry on the 

 work of destruction. 



I have before intimated that sun blight is more likely to be 

 found in Southern Illinois than in the Central and Northern part of 

 the State, and such seems to be the case. Where the ground freezes 

 to a great depth there is little or no activity in the roots, and there 

 will be less moisture in the partially thawed cells. With us, there is 

 probably no one cause that is more ])otent than sun-blight, and its 

 attendant, the flat-headed borers, in destr(^ying orchard trees. The 

 disease does not seem to be confined to any particular varieties of 

 ap])le trees, nor is it found affecting this kind of fruit tree alone. 

 Peach, pear, cherry, and, in fact, many of our forest trees seem to be 

 subject to it, as we might expect, if the causes as here given ai*e cor- 

 rect. Immunity from the disease seems to be due more to the habit 

 of growth or training of a tree than to kind. If a tree has the limbs 

 branching from the trunk within a few feet of the ground, and if 

 these extend all around the body, or more particularly on the south- 

 west side, it will be found to be free from sun blight, if, on the 

 other hand, the limbs are well up from the ground so that the trunk 

 is ex}josed, or the liml)s extend lu'arly straight u})war(l from their 

 origin, such a tree is pretty sure to be blighted. A tree that leans 

 to the northeast is more easily exposed, and hence more subject to 

 bliglit than one that stands erect or leans to the south or southwest. 



