456 EXPERIMENT STATION RECORD. [Vol.37 



Cleopatra. It is stated that the tendency to bitter pit is more or less inherent 

 in the constitution of the cultivated apple, no matter where it is grown. 



Bitter pit is considered a functional di.sorder, the vascular system, or con- 

 ducting tissue, being largely concerned. The cultivated apple has evidently 

 lost, in large degree, the hardy nature of its wild ancestors, its vascular sys- 

 tem having failed to keep pace with the requirements laid upon it during the 

 development of such various desirable qualities as size. A softening of the 

 fiber, a delicacy of constitution, and a feebleness in the power of rapid trans- 

 portation of water, etc., have necessitated measures to counteract the inade- 

 quate conduction iu the tissues. 



Studies on the relation of laterals to bitter pit were inconclusive. Ringing 

 and fracturing the branches was tried, and it was found that checking the flow 

 of «ap in September resulted in a diminution of pitting, and for the last two 

 seasons there was none at all. The results from constricting the branches with 

 wires were inconclusive, as were those from ringing j)ear trees. The fall of 

 the leaves was not affected. 



Observations described seem to indicate that apples should not be kept in 

 an ordinary storeroom where the air is overdry. In ca.se of apples on the tree, 

 the temperature of the atmosphere and its humidity appear to modify the effects 

 of the sun's rays. Slightly less pit developed in apples grown in sheltered situa- 

 tions, transpiration being reduced when the drying effects of vrind are 

 moderated. 



A study of bitter pit in its relation to weather shows that it is not strong 

 transpiration in dry air or weak transpiration on dry soil that induces bitter 

 pit, but that it is the amount of transpiration relatively to the water supply 

 that is the important factor. The general evidence indicates that the nature of 

 the scion, and not that of the stock, is the deciding factor in varietal suscepti- 

 bility. As regards situation, the least suitable is one having a southerly ex- 

 posure, and the most favorable is one having a northeasterly aspect, well 

 sheltered from west and south winds. 



Of all orchard operations, pruning appears to have the most direct effect 

 upon the development of bitter pit. which is least prevalent when there is a 

 good average crop with fruit, generally of normal size, well distributed over the 

 tree. The pruning operation should be carried on continuously from the time 

 of planting through the bearing period. The objects to be aimed at are uot only 

 increased vigor and luxuriant growth, but also the distribution of the fruits on 

 the tree so that each receives its due share of sun. shade, air, and nourishment 



While many facts and suggestions are variously presented in the body and 

 conclusion of this report, it Is thought that the ultimate solution of the problem 

 must be obtained from breeding experiments looking to the production of otlier- 

 wise desirable varieties which do not develop bitter pit 



A brief bibliography is appended. 



Xylaria root rot of apple. F. A. Wolf and R. O. Cbomweli. (P. S. Dept. Agr., 

 Jour. Agr. Research, 9 (1917), No. 8. pp. 260-276. pi. 1, figs. .?).— In continua- 

 tion of a preliminary report on the black root rot of apple (E. S. R., 36. p. 

 147). the authors give an account of further investigations carried on at the 

 North Carolina Experiment Station on this disease. This trouble is found to be 

 widely distributed in North Carolina, and it is believed to be the same di-sease 

 which has been reported in Virginia and Pennsylvania. 



There are said to be no above ground symptoms by which this disease may 

 be distinguished from other apple root rots. The roots, however, are said to 

 be characteristically covered with black fungus incrustations from whose mar- 

 gins radiate minute black rhizoniorphs. Isolations have constantly yielded a 



