July, 1917.] GROWTH OF APPLE TREES. 17 



method is fairly good but has some objections which make it 

 somewhat faulty. In the first place there may be a heavy water 

 sprout growth on the tree which must be eliminated, and also 

 there is great variation in the length of what might be consid- 

 ered "normal growth," and the relatively small number of twigs 

 which it is physically possible to measure in a large orchard is 

 quite small, so that the final figure arrived at is not entirely 

 satisfactory. There is also the personal element which enters 

 in when different men make the observations from year to year 

 that may fail to make the figures exactly comparable. Another 

 method for attempting to secure the index of growth is to caliper 

 the trees at a given distance from the ground and take the diam- 

 eter growth as the index. This would seem to be more accurate 

 in many ways and this method has also been employed since 

 1913, and both data are given below in Tables No. 6, 7 and 8. 



SCHEDULE OF TREATMENT OF PLOTS.* 



Crimson clover is used as a cover crop in every case. Seed is 

 sown July 10 at the rate of 20 pounds per plot. In seeding plots 

 2 and 3 the following mixture is used: 

 10 pounds timothy 

 10 pounds red clover 

 5 pounds white Dutch clover. 



Plot 1. Sod. To remain permanently in sod. Grass to be 

 mown when inconveniently long and allowed to remain on 

 the ground. No fertilizer to be applied. 



Plot 2. Cultivated the odd year, cover crop sown July 10, 

 seeded the even. No fertilizer is applied. 



Plot 3. Cultivated the even year, cover crop sown July 10, 

 seeded the odd. No fertilizer is applied. 



Plot 4. Clean cultivation. This plot is plowed every spring 

 and cultivated every two weeks until September 1. No 

 cover crop is sown and no fertilizer is applied. 



Plot 5. Cultivation and cover crop. This is plowed every 



spring and cultivated every two weeks. A cover crop con^ 



sisting of 20 pounds of crimson clover is then sown. No 



fertilizer is applied. 



* For more extensive description of orchard ftftd soil, see Tech. Bull. I^o, 9, 



