iThe Canadian Horticulturi^ 



^ol. XXXII 



OCTOBER, 1909 



No. 10 



Overcoming Winter Injury* 



W. T. Macoun, Horticulturist, Centr&l Experimental Farm, Ottawa 



WINTER injury to fruit trees causes 

 great loss to fruit growers in the 

 colder parts of the United States 

 and Canada every year, but in some 

 years the losses are so great that in many 

 cases discouragement follows and new 

 trees are not planted. Even in the vifarm- 

 er parts of the United States and Cana- 

 da where the tenderer kinds of fruit are 

 grown an occasional severe winter de- 

 stroys many an orchard which after years 

 of care had begun to bear profitable 

 crops. We have been asked at this time 

 to prepare a paper on "Overcoming 

 Winter Injury," but it must be admit- 



kted at the outset that the best known 

 methods of overcoming winter injury are 

 ilot entirely satisfactory. 

 ' None of the important tree fruils grwn 

 in North America are indigenous. The 

 apple, pear, domestic or European plum, 

 Japanese plum, cherry, peach, orange 

 and lemon are all natives of the old world 

 and it would be difficult to find any dis- 

 trict in North America where the cJimate 

 both of the air and soil, is the same as 

 where these fruits grew or grow wild in 

 Europe or Asia. Centuries of acclimati- 

 zation fixed limits beyond which these 

 fruits did not perpetuate themselves, or, 

 at least, spread but slowly, being pro- 

 bably killed out at their outer limits by 

 very exceptional climatic conditions, eith- 

 er of summer or winter, occurring after 

 long intervals, perhaps even of centuries. 

 It is not to be wondered at that these 

 fruits transported to other climates which 

 at first glance seemed to be very similar 

 in most particulars to those in which 

 they flourished at home, do not perpet- 

 uate themselves. It may be that there 

 is not enough snow in the winter and the 

 roots are killed, or it may be that it is 

 too dry in summer and the trees die of 

 drought, or it may be that the air is too 

 dry in winter and the trees dry out. Too 

 much rain late in summer may start the 

 trees into new growth and they are in 



•A part of a pappr read at the meeting of the 

 American Pomological Society, held at St. Cath- 

 arines, Ont., in September. The forms of winter 

 injury mentioned in the concluding paragraph 

 of the matter herewith published already have 

 been discussed by Mr. Macoun in the columns of 

 Thk Canadia.v HoKTinuLTriiiHT and of Farm anil 

 Dairy, which is published in tlio same ofBce. Any 

 person not familiar with what Mr. Macoun hag 

 said on these subjects, may secure copies of Mr. 

 Uacoun's report for year ending March 31, 1908, 

 by writing to the Central Experimental Farm, 

 Ottawa. 



bad condition to withstand the low tem- 

 peratures of winter, and frequent 

 changes in temperature in winter from 

 high to low temperatures, and vice versa, 

 may be new and too trying experiences 

 for these imported fruits. It will re- 

 quire a long time to determine in what 

 parts of America these fruits will become 

 naturalized and what the limiting factors 

 are which prevent their survival In other 

 parts. While these trees are said to be 

 hardy if they survive a few generations 

 in a particular district, this term is only 

 used in a relative sense. True hardiness 

 is adaptability to environment not for a 

 few generations or a few centuries but 

 for many centuries. No Increase In the 

 ability of individual specimens, which 



Delightful and Instructive 



The Canadian Horticulturist 

 Is not only a source of delight for 

 one interested in horticulture, but 

 unusually Instructive on things 

 that pertain to the culture of 

 plants, shrubs and fruits. It is 

 to me a treat to read the well writ- 

 ten essays, including the discus- 

 sions on the Improvement of home 

 grounds and of parks. — A. E. 

 Small, Buffalo, N. Y. 



were half hardy or which killed to the 

 ground twenty years ago, to withstand 

 adverse climatic conditions at Ottawa, 

 has been noticed at Ottawa. 



The natural perpetuation of the species 

 or variety, or the extension of Its range 

 when not under cultivation, need not, 

 however, cause any anxiety to the fruit 

 grower. His object is to extend the suc- 

 cessful culture of the different fruits over 

 as wide a territory and as great a diver- 

 sity of climates as possible, and he can, 

 if his trees are all destroyed, soon plant 

 a new orchard of the same varieties from 

 other sources ; whereas in nature long 

 periods might elapse, after a series of 

 exceptional years, when there had been 

 great destruction to trees, before the 

 range of the species was again extended. 



There is a great difference in the hardi- 

 ness of varieties of the same kind of fruit 

 and it is only by experiment that man 

 is able to determine what varieties will 



2U 



continue hardy long enough in his dis- 

 trict to make it profitable for him to 

 grow them. He finds by experience that 

 the hardiest fruits for him come from 

 the climates in the old world, or In Amer- 

 ica, most nearly resembling that In which 

 he lives, or they come from varieties 

 which are descended from species which 

 come from climates most nearly resemb- 

 ling his own. Thus the first step In over- 

 coming winter injury Is to plant the 

 hardiest varieties. Unfortunately, the 

 hardiest varieties are not always the best 

 In color, or quality, or may not be of the 

 season of maturity which Is desired. Man 

 obtains what he wants by crossing the 

 hardiest varieties with those having the 

 other characteristics. He may extend 

 the limits of the successful culture of the 

 different kinds of cultivated fruit by 

 crossing them with the native species. 



There are not yet, however, sufficient 

 hardy fruits having all the other desir- 

 able qualities, which are suited to all the 

 climates in America where man would 

 like to grow fruit, hence It is usually 

 necessary to grow fruits which may not 

 always prove hardy when there are un- 

 favorable summers and exceptionally se- 

 vere winters. In such cases, and they 

 are numerous, it Is necessary to resort to 

 special methods of culture as an aid to 

 overcoming winter Injury. 



It is not our purpose In this paper to 

 deal with winter injury in the south, as 

 we are not familiar enough with the con- 

 ditions there to discuss the matter, but 

 we believe that some of the methods here 

 suggested of overcoming winter injury 

 may be usefuF even in the citrous belts. 



The Central Experiment Farm, Otta- 

 wa, Canada, is situated In latitude 45 de- 

 grees north, and 75 degrees west longi- 

 tude. There Is usually a sufficient supply 

 of moisture and heat during the growing 

 season to cause a strong growth on 

 healthy trees of apple, pear, domestica 

 plum, cherry and peach, and there is usu- 

 ally a good covering of snow to protect 

 the roots of the trees in winter. The 

 temperature in winter seldom goes as 

 low as 30 degrees F. below zero, and 

 very rarely any lower. Winter sets in 

 as a rule during the latter part of No- 

 vember with the ground frozen and there 

 are usually few thaws between that and 

 the middle of March. The snow, as a 



