APPLE DISEASES 



497 



Fig. 1. W'intei' Injury to Youdr Apple Tree. 



formed. There is great danger ot sep- 

 aration of the bark layer from the wood 

 at that time as at others. The sun ex- 

 posed side seems to suffer worse by rea- 

 son of the more extreme temperature 

 changes which were incited on these ex- 

 posures. It is evident that warm periods 

 In winter are a source of danger when 

 followed by low temperatures. 



Upon very large trunks near the base, 

 as on Grimes and some others, this may 

 be the real explanation of frequent sun 

 scald or basal injuries. Wherever such 

 an injury begins there is risk of the in- 

 trusion of wound fungi with all the con- 

 sequences which follow their entrance. 

 The handling of winter injuries must, so 

 far as prevention goes, precede the condi- 

 tions which cause it. Where possible the 



prevention of excessive late growth is de- 

 sirable. In cases of orchard trees it may 

 be that mulches of coarse litter, espe- 

 cially, will prove serviceable. It may be 

 added that this injury to woody growths 

 is a less developed phase of the killing 

 back of herbaceous plants by the prema- 

 ture frosts. 



Another phase still is the killing back 

 of branches at the tips of woody growth 

 which are not strictly hardy in our cli- 

 mate. In the case of our Japanese plum 

 and of some ornamental shrubs, this is a 

 frequent phenomenon and its cause is to 

 be sought in the same factors above de- 

 scribed. Growth being protracted late in 

 the season, these water-gorged terminal 

 twigs are killed by the subsequent winter 

 freezing whenever this is severe. 



See Sun ScaJd. 



A. D. Selby 



Winter Injury and Cankers 



Ben Davis and Gano apple trees died 

 in such large numbers throughout Iowa 

 during 1912 season that the Iowa Agri- 

 cultural Experiment Station Horticultur- 

 ists, S. A. Beach and Lauren made a 

 thorough investigation of the districts 

 most affected. In their preliminary re- 

 port they say that injury and death of 

 these fruit trees is due to a number of 

 factors, chief of which are cankers and 

 blight caused by various parasitic dis- 

 eases; the early fall freeze of October, 

 1909; the late spring freeze of April. 

 1910; the dry season of the summer of 

 1910, followed by the cold winter with 

 comparatively light snow, and the ex- 

 treme drouth and heavy crop production 

 of 1911. 



All of these factors tended to weaken 

 the vitality of the apple trees, and par- 

 ticularly of the older and less vigorous 

 ones, rendering them less able to with- 

 stand the unusual and continued low 

 temperatures of last winter. Those or- 

 chards which had been well cared for are 

 showing less injury than neglected or- 

 chards and their trees are recovering 

 more rapidly. Also, the younger and 

 more vigorous trees recovered more rapid- 

 ly; they were also less injured. 



In general, those trees which were 



