AusUi^t, '12] BACK AND PRICE: STOP-BACK OF PKACH 329 



STOP-BACK OF PEACH 



By E. A. Back and W. J. Price, Jr., Virginia State Crop Pest Commission, Blacks- 

 burg, Virginia 



For many years, nurserymen have been troubled by a disease of 

 peach nursery stock known as ''Stop-back" resulting in the death 

 of the tender terminal bud of the principal shoot. The injury to the 

 terminal shoot forces the development of lateral shoots, the terminal 

 buds of which may in turn be affected in a similar manner. When 

 this trouble is spreading sl'c its greatest rapidity, not a single terminal, 

 and even many of the lateral buds, of both the principal and lateral 

 shoots are killed and the plant remains dwarfed and fails to develop 

 into a tree designated by the nursery trade as A No. 1. Frequently 

 the trees are so stunted by the successive deaths of the terminal buds 

 that they are absolutely worthless. Many trees, however, are only 

 sufficiently affected to make them undersized and very crooked, and 

 while they may make as good trees for orchard planting, they must 

 be sold at a price which means a substantial loss to the nurseryman — 

 a loss that in 1911 in Virginia amounted to about $5,000, and in Penn- 

 sylvania to about $15,000. 



From time to time, various creatures have been said to cause this 

 Stop-back. Prof. M. B. Waite in a paper before the Biological Society 

 of Washington during 1897 stated that a mite was responsible for the 

 injury. In 1896, Prof. W. G. Johnson noted many stunted peach trees 

 during his inspection work in Maryland and upon examination, found 

 a minute mite associated with the trouble. Dr. J. B. Smith in 1899 

 believed that Stop-back in New Jersey was caused by "Peach Thrips." 



Prof. W. B. Alwood of the Virginia Agricultural Experiment Station, 

 who had observed Stop-back since 1891, considered Thrips responsible 

 for the injury. Mr. J. L. Phillips, formerly of this Commission, in the 

 fifth report of the Virginia State Entomologist, stated that he consid- 

 ered that mites were the causative agent. IMessrs. Webster and Mally, 

 in an article on "Insects of the Year in Ohio," read in August, 1899, 

 stated their belief that Stop-back was due to the work of the common 

 tarnished plant -bug, Lygus pratensis L., since they found no mites 

 present and the extent of injury to peach in proportion to the abund- 

 ance of the bug. Prof. A. L. Quaintance in a paper on "The Peach 

 Bud Mite" published as part six of Bulletin 97 of the U. S. D. A., B. E., 

 Feb., 1912, states that a mite is apparently responsible for Stop-back. 

 He has had the mite in question identified hj Mr. Banks as Tarsone- 

 mus waitei Banks, and discusses its systematic relationships, and 

 other allied economic species of mites belonging to the same family, 



