July, 1917.] GROWTH OF APPLE TREES. 25 



orchard. The curves do not follow exactly and yet they show 

 about the same general form. Which one would come nearest to 

 a correct index of growth would be difficult to say, but the writer 

 is of the opinion that a majority of workers would prefer the 

 caliper measurements. However, he is inclined to the opinion 

 that when the twig measurements are carefully made on mature 

 bearing trees which are under the same type of treatment annually 

 and without radical changes in pruning that the twig data are 

 fairly representative of the growth of the tree. Nevertheless, 

 since the diameter measurements are so much simpler to make, 

 it might seem more desirable to adopt that procedure in similar 

 experiments. 



SUMMARY. 



To summarize the effect of cultural treatments and fertilizers 

 on growth in this orchard it can be said that the amount of growth 

 made in the sod plot is not sufficient to keep the trees in a vigorous 

 and productive condition, neither can they overcome the cankers 

 with which they are troubled (mostly Sphaeropsis Malorum and 

 Nummularia discreta). Clean tillage alone greatly stimulated 

 growth at first but in recent years it has not maintained the 

 growth of the first few years. Where a cover crop is plowed in, 

 the growth is a little better than under clean tillage but the 

 amount of material we grow on this unfertilized land is apparently 

 not sufficient to maintain the growth the trees made at first. 

 Complete fertilizers, in addition to the clean tillage plus a cover 

 crop, did not increase the growth of the trees to a greater extent 

 than where no fertilizer was applied during the first six years of 

 the experiment but since that time all the fertilized plots have 

 been gaining constantly in their growth until the past season 

 (1916) they averaged 26 per cent greater growth than where no 

 fertilizer was applied. In 1916 it was noticeable to the eye for 

 the first time the difference in color of the foliage where fertilizer 

 was applied. This fact is in decided contrast to orchards stand- 

 ing in sod where a nitrogenous fertilizer is applied, for in the 

 latter case we can often see a difference in a few weeks. 



An average of three years records shows a fair degree of cor- 

 relation between twig and diameter measurements. However, it 

 is assumed, that the increase in the diameter of the trunk is a 

 better index of the growth pf the tree than the twig measurements, 



