268 FUNDAMENTALS OF FRUIT PRODUCTION ' 



INJURIES ASSOCIATED WITH IMMATURITY 



Early maturity of wood is of paramount importance in most of the 

 northeastern United States and is by no means a negligible factor outside 

 that region. Most of the injury in Washington state orchards in the 

 disastrous freeze of late November, 1896, can be attributed clearly to 

 immaturity rather than to the actual temperature ( — 12°F.) attained. ^^ 

 Any region with a comparatively short growing season and with fairly 

 heavy late summer and autumnal rainfall is subject to winter killing 

 because of immaturity. Other combinations of conditions may produce 

 occasionally the same susceptibility in regions ordinarily free from these 

 dangers. Thus in most irrigated sections climatic conditions are such 

 that injuries of this type are not to be expected; however, they are fre- 

 quently brought about by the injudicious use of irrigation water early 

 enough in the autumn to prolong growth. In the freeze of 1896, in 

 Washington, most of the orchards that had been irrigated in late summer 

 suffered more than others. ^^ L^te irrigation should be very late, if 

 immunity to this form of injury is to be insured. Furthermore, it should 

 be borne in mind that maturity is only a relative term, the so-called 

 "maturity" of the Willamette valley, for example, being quite different 

 from the "maturity" of Wisconsin. Therefore, a given temperature, 

 common in Wisconsin but unusual in the Willamette, might be harmless 

 in the one location but very injurious in the other, even to trees of the 

 same variety. 



Much of the damage from winter temperatures in England and in 

 northern France and Germany is evidently associated with lack of ma- 

 turity, since particularly cool summers followed by winters of moderate 

 severity have frequently proved more damaging than colder winters that 

 followed favorable growing seasons. A "cold winter" for England 

 would be considered mild in the northern states or Canada; in England 

 it might cause considerable damage and none in New York or Michigan. 

 The prevalence of "frost cankers" as the chief manifestation of winter 

 injury in England lends weight to this view. 



Affecting More or Less the Entire Plant. — Emerson^" states: " Resist- 

 ance to cold in trees is due often almost wholly to the habit of early 

 maturity rather than to constitutional hardiness. Black walnut trees 

 at the Experiment Station (Nebraska), grown from northern seed, by 

 virtue of perfect maturity, passed through the extremely severe winter of 

 1898-1899 without apparent injury while similiar black walnut trees from 

 southern seed, owing to imperfect maturity, have had their new growth 

 killed back from a few inches to two or three feet for the past six years and 

 yet notwithstanding this great difference in resistance to cold in winter, a 

 comparatively hght freeze late in the spring of 1903 killed the new growth 

 of the northern trees just as completely as it did that of the southern ones. 



