Grossenbacher Radial Growth in Trees. 45 



cases it was found to occur equally late in the upward extension 

 of such a root-ridge on the trunk. Again, in some instances in 

 which trees had only two large lateral roots making a rather 

 narrow angle with each other, very late growth was found to oc- 

 cur in the valley-like angle between them. From an earlier pa- 

 per 88 on crown-rot and the papers cited there it is interesting 

 to notice that the distribution of that disease on fruit trees con- 

 forms fairly closely to the distribution of late radial-growth oc- 

 curring at the root-crown region. It was found that in cases 

 where only a part of the bark was affected it was confined to the 

 upper angles of lateral roots, or to the very deep angles between 

 two large laterals. 



Pruning fruit trees very heavily often results in a decided re- 

 duction in the thickness of the next annual ring toward the base 

 of the trunk. This was found by pruning some fruit trees in 

 one of the seedling apple orchards of the New York State Agri- 

 cultural Experiment Station in early spring of 1912. The ra- 

 dial growth on the lower part of such heavily pruned trees also 

 continued several weeks later than it did 011 nearby checks.* 



The result seems to agree with those obtained by Jost, Lutz, 

 and Kiilins 89 in that a reduction of the foliage beyond a certain 

 amount resulted in greatly reducing growth toward the base of 

 the stem. 



As stated above observations made regarding the occurrence of 

 crown-rot on fruit trees seemed also to show a possible relation 

 of that disease to the distribution of late growth. Some New 

 York apple orchards may be used to illustrate this relation. In 

 one instance 90 two varieties almost equally susceptible to crown- 

 rot were grown side by side and received the same treatment ex- 

 cept that the Baldwin variety was pruned up high while the 

 other or Ben Davis variety was allowed to grow largely unpruned 

 and therefore low headed. The Ben Davis trees had been set 

 for fillers and were not deemed worth the care bestowed on the 



88 Crown-rot, arsenical poisoning and winter-injury. N. Y. State 

 Agrl. Expt. Sta. Tech. Bui. 12:389-94. 1909. 



* The writer wishes to thank G. H .Howe of that station for having 

 the pruning done, and R. Wellington, now of the Minnesota Experiment 

 Station, for making some of the collections of specimens from these 

 trees into killing fluids. 



89 1. c. 



90 Crown-rot of fruit trees: field studies. N. Y. State Agrl. Expt. Sta 

 Tech. Bui. 23:18-20, 46, and plate 7. 1912. 



