SOME OBSERVATIONS ON THE GROWTH OF APPLE 



TREES. 



J. H. GOURLEY. 



The present paper contains some observations on the growth 

 of mature apple trees growing under different systems of cul- 

 ture for a period of nine years. In addition to recording the 

 annual growth we have also made daily growth measurements 

 for three seasons 1913, 1914 and 1916, which are here presented 

 in connection with certain external factors which influence the 

 growth of plants. Soil temperature and moisture, air humidity 

 and temperature, and rainfall have been carefully recorded in 

 this orchard which adds to the interest of the daily growth be- 

 havior. Since these data represent 43,000 measurements during 

 three seasons they give us a pretty accurate knowledge of the way 

 these trees behave under field conditions with no attempt made to 

 control the external factors. 



SUMMARY. 



1. Soil temperature runs lowest under the heaviest vegetation 

 and highest under clean culture during the summer and reverses 

 this order during winter in the orchard under observation. 



2. In the ninth year of this experiment the trees under a system 

 of cultivation with cover crops exceeded in annual twig growth the 

 trees in sod by 80 per cent. All the plots receiving a complete 

 fertilizer in addition to cultivation and cover crops showed a 

 marked increase in twig growth after the sixth year of the ex- 

 periment and in the ninth year these plots averaged 26 per cent 

 greater twig growth than the plot \rithout fertilization. A dif- 

 ference in color of the foliage, however, was not noticeable until 

 the ninth year and no increase in yield has yet occurred. The 

 clean culture plot did not average as great an annual twig growth 

 in the second four-year period of the experiment as in the first 

 four-year period but in the ninth year was 58 per cent greater 

 than the sod plot. The yields, as yet, have not been so affected 

 in the clean culture plot. 



3. The daily growth was more or less erratic each season, i. e., 

 not following consistently any external factor under observation. 



