12 HJSTORV <>1' HriRTiCri/rrRK iX MINNESOTA. 



Of the aiinost innumeralile varieties; of standard fruits, we have to discover the kinds 

 adapted to our soil and climate, and there are comparatively only a small number of each 

 sort of fruit adapted to any particular locality. Some varieties, no doubt, succeed best in 

 one part of our State, and others in another. A few varieties, however, appear to flourish 

 in every part of the State, when the conditions necessary to tree-life are observed. 



Mr. Rollins, of Wabasha county, one of our successful fruit growers, pronounces several 

 kinds of apple trees worthless, which others have found to be hardy and have fruited, among 

 which is the Early Harvest, that has done exceedingly well in many parts of the State. This 

 is true, also, but not so generally, of the Ehode Island Greening. 



Mr. Rollins states also that his young trees — seedlings, Ave suppose— were badly injured in 

 October last, by the frost, which split the bark and discolored the sap of many of them— the 

 first time he has seen apple trees damaged in a similar way. Like effects are produced 

 from the same cause in the Middle States. Young trees are more tender than the old, because 

 they are more succulent, and have not a hard, close, internal structure, and a rough bark to 

 protect them from the effects of alternating temperatures. To assume that young seedlings, 

 because grown in our soil, are necessarily hardy here, is erroneous. As a general rule, our 

 young seedlings will require greater care than the older nursery trees, of the hardy varieties, 

 brought from more southern latitudes. 



And now. what is the etl'ect of frost on our fruit trees ? This is our M innesota stumbling 

 block in the enterprise of fruit culture. Mr. Bell, of Dakota county, expresses the general 

 opinion, that it is frost which kills our fruit trees, and deters so many from any attempt to 

 raise tree-fruit, except the Siberian Crab. If it is the cold or frost that kills our fruit trees, 

 we may as well abandon their cultivation in the open air. for we cannot hope to raise an 

 apple tree to bearing maturity, without exposing it , one or more times, to 40 degrees below 

 zero— to a sufficient degree of cold to Ireeze quicksilver. 



Now, we maintain, and believe the assertion to be capable of demonstration, that it is not 

 the frosts, but the rays of the sun, that do the mischief. This generally occurs Avhen the 

 sap of the tree has been frozen, after it has begun to circulate in early spring. We explain it 

 thus: — The tree is built up of cells of various forms and uses, the diff"erent systems of which 

 are closelj^ compacted, forming continuous masses of pith, wood and bark. Part of these 

 cells contain juices, or sap of different kinds; part contain air, which produces chemical 

 effects upon the sap of the tree, analogous to air in the lungs upon the blood of animals. The 

 tree, like the animal, has its organs for inhaling and exhaling air, which are necessary to its 

 life. These organs are called cells or ducts. Any cause which bursts them will produce 

 hemorrhage, for the sap will then run into them as blood into the lungs. There is then dis- 

 organization, which, if extensive, kills the tree. If we examine the bark of one of our trees 

 thus injured, Ave will find that this disorganization pervades that part of the stem or trunk, 

 on the side and spot most exposed to the mid-day or tAVO o'clock sun of Spring. The process 

 of freezing converts water into crystals , increasing its bulk Avith a powerfully expansive 

 force. In our city, we have seen the iron gas pipes burst from this cause. But air is 

 condensed by frost. As the cells of the tree containing sap enlarge in the process of freezing, 

 those containing air contract in an iuA'erse ratio, so that the bulk of the structure remains 

 about the same. The freezing is gradual and therefore does not burst the sap cells, which 

 have the necessary degree of elasticity to admit of gradual expansion. If the air and sap 

 expanded alike in freezing, the death of all the trees in our forests would be inevitable. 

 They AAOuld be split to pieces with terrible explosions. When the tree in Avhich the full 

 current of circulating sap has been frozen, is fully exposed to the direct raj-s of the sun, the 

 air cells on the side exposed to the sun are rapidly expanded before the frozen sap begins to 

 melt. This expansion bursts the air cells in the part of the stem thus exposed, an effect 

 which could not take place, if the frozen sap Mere melted and thereby condensed, as rapidly 

 as the heated air in the air cells expanded. By thawing gradually, which must be without 

 exposure to the direct rays of the sun, the heating and consequent expansion of the air, and 

 the melting and accompanying contraction ot the previously frozen sap, maintain the neces- 

 sary degree of equilibrium. The tree then passes through the process of freezing and thawing 

 without the slightest injury. We therefore deduce the proposition, that our trees are not 

 killed by frost, but by heat from the sun. And this is the case in all the Middle States, as 

 well as Minnesota. 



It may be asked why our native forest trees are not killed in like manner when thawed 

 by the sun. We know that they are not. They must, therefore, have an organization which 

 secures an equilibrium of forces in the expansion of the air and the condensation of the sap 

 in their cells, independent of the external influences which aftect our imported exotic trees. 

 There are a few varieties of fruit trees, natives of the extreme north, no more liable to injury 



