560 EXPERIMENT STATION RECORD. 



as to overload and weaken the tree. Thinning the crop below this limit is, there- 

 fore, of no advantage. Cutting back the trees at the time of planting out has resulted 

 in more fruit than where the trees were not cut back until a year later. Unpruned 

 trees have borne crops three times the value of those pruned severely and 50 per 

 cent greater than those pruned moderately. It is thought that with precocious trees 

 these results might not hold. 



Summer pruning, shaping, and pinching have not produced useful results. No 

 difference in results has been observable whether trees were pruned in the early fall, 

 midwinter, or spring, or whether they were pruned during or just before hard frosts. 



Root pruning trees every year practically stopped all growth. Less frequent root 

 pruning resulted in proportionately less injury. Recovery began the second year 

 after root pruning was done and was accompanied by relatively heavy fruiting. Two- 

 year-old bush apple trees proved better for transplanting than 1, 3, or 4 year old trees. 

 Two-year-old standard trees also proved better than 4-year-old trees. 



The effect of grass 5.5 and 6 ft. away from apple trees produced marked results. 

 The crops on these plats were more than double the normal wdthout any diminution 

 in the size of the fruit. The fruit which normally was of a deep green, occasionally 

 tinged with red, assumed a brilliant red color, and in storage kept much better. 

 The variety Potts kept 3 months longer than usual, and Bramleys were still good in 

 June at the time of waiting. 



The serious injury of grass on the growth of apple trees, when it occupies the whole 

 area under the trees, was brought out in former reports (E. S. R., 12, p. 749; 15, p. 

 474). The present experiment is believed to illustrate how a kind of treatment that 

 is very injurious when carried to excess may be very beneficial when adopted in 

 moderation. The amount of tree roots which entered the grass area was determined 

 in 3 instances and amounted to but 0.9 to 2.4 ounces per tree. "Yet they must have 

 conveyed something to the trees which has been sufficient to modify the whole char- 

 acter of the crop. This points strongly to the view that the action of the grass is 

 due to some active poison." 



Notwithstanding increased crops, higher colored fruit, and improved keeping qual- 

 ity, growers are cautioned against attempting to improve their fruits by partially 

 grassing over their orchards, since the line between beneficial and injurious effects 

 of grass is very narrow and requires further stud}'. No difference has been noticed 

 in the action of different grasses on the fruit. Grassing over pears, cherries, and 

 plums has led to the same injurious effects as with apples. The application of iron 

 sulphate or manganese sulphate at the rate of 27 lbs. per acre has had no noticeable 

 influence on the color of apples. 



Careless planting of trees, such as hacking off the roots with the spade, huddling 

 them into too small holes when planting, pointing the roots downward, tilling in 

 the holes and packing down the dirt without any attempt at working it in around 

 the roots, resulted in impairing the vigor of the trees during the first year or two, 

 after which the trees recovered and at the end of 3 or 4 years had made a much 

 better growth on an average than trees planted carefully according to accepted 

 methods. 



The reason for this better growth is thought to be explained by some other experi- 

 ments in which trees were planted 2 ft, deep or more. The roots of the trees thus 

 treated made no growth, but a new system was established from dormant buds at the 

 usual depth, after which these trees made unusually good gains, overtaking trees 

 planted normally. The point is made that this entirely new root system which had 

 never been disturbed by transplanting served the trees better than the old system, 

 and it is held that careless transplanting, combining the methods noted above, would 

 likely lead to the establishment of a new root system. 



Shortening the roots one-third of their length at the time of transplanting impaired 

 the vigor of the growth of the trees but little, but removing two-thirds seriously 



