40 PEACH YELLOWS. 



year, and were planted in three badly affected orchards farther up the 

 peninsula. 



(a) The trees which went to James W. Greeii, Magnolia, Delaware, 

 were set in the southwest corner of an orchard on his home farm, No. 

 14, map iv, of my first report. Yellows appeared in this orchard in 

 1886 and has been very destructive, more than 50 per cent of the trees 

 having become affected. Thedisease is also very prevalent in neighboring 

 orchards, including a younger one on the same farm. The spot selected 

 was specially adapted to the experiment, because the disease first ap- 

 peared in that part of the orchard, and speedily involved many trees. 

 In 1889 this corner of the orchard contained very few healthy trees, 

 but none had been dug out, and none were entirely dead. The diseased 

 trees were removed in March, 1890, and the land then received a heavy 

 dressing of barnyard manure, i. e., over 100 loads. The young trees, 

 which had been trenched in over winter, were then set in the spots pre- 

 viously occupied by the affected trees, each being given a handful of 

 phosphate. One hundred and thirty-six trees were sent to Mr. Green 

 (94 Beers' Smock and 42 Old Mixon), but only 124 were set. Some were 

 quite small, but all were healthy. The Smock trees were planted next 

 the highway. 



These trees were under observation from time to time during the 

 growing season and were critically examined September 18, 1890. Only 

 47 had made a satisfactory growth. Of the remainder, 24 were dead 

 and 53 were dwarfed and yellowish as though suffering from defective 

 nutrition. None, however, showed any signs of yellows. These trees 

 received good cultivation, were not shaded, and did not appear to be 

 suffering from root aphides* They had been set very deep, and 1 

 was at a loss to account tor the appearance of the sickly ones, unless 

 this might have to do with it. Later, I discovered that in all of the 

 dwarfed and yellowish trees the tops had overgrown the stocks, and 

 that in all the vigorous trees the growth of the stocks had kept even 

 pace with that of the tops. The dead trees were killed in spring by the 

 black peach aphis, which sapped and smothered the tender shoots. 



(b) The trees which went to F. H. Harper, Still Pond, Maryland, 

 were planted in the east end of one of his orchards on the Howard farm, 

 No. 6, map n, of my first report, in places made vacant by the removal 

 of diseased trees. This orchard also appeared to be a good place to try 

 the resisting power of healthy trees. Yellows first developed in 1886 

 and is still present, the cases having amounted to over 25 per cent of 

 all the trees. The disease is also very prevelant in other orchards in 

 the vicinity, including a younger one on the same farm. 



Mr. Harper received 125 trees 50 Mountain Eose and 75 Crawford's 

 Late. All were healthy, of medium size, and in good condition for 

 planting. Part of them were set in November and the remainder in 

 early spring. In some cases the diseased trees were removed just pre- 

 vious to this planting ; in others, they had been out for a year or two. 



