EXPLANATION OF PLATES. 57 



XVIII. Year 1890. From same series as XIII to XV, but 13 months later. 

 Trees diseased by yellows in all parts and very sickly. Fig. 1 

 shows the best one of the 210 inoculated trees. Fig. 2 nearly dead. 

 Time 3 years from inoculation. Trees 41 months old. Photos. July 

 30, 1890, Hubbardston, Mich. 



XIX-XXI. Year 1890. Plates showing effect of inoculations on seven previously 

 healthy trees. Different stages of the disease. Time 3 years. Some 

 entirely dead and others nearly so. Fig. 1, Plate XIX, shows two of 

 a row of healthy trees in the background. The very characteristic 

 branching shoot on the base of Fig. 2, Plate XXI, did not grow from 

 the inserted bud x but from the seedling stock some distance above 

 it. Photos. July 30, 1890, Hubbardston, Mich. 



XXII. Year 1890. Forty trees killed by yellows in less than 3 years from 

 date of inoculation. Pulled and photographed in one group. July 

 31, 1890, Hubbardston, Mich. Some died ia the fall of 1889, others in 

 the following winter, and the small remainder in the spring of 1890. 

 XXIII, XXIV. Year 1890. Two unbudded healthy trees of same age for comparison 

 with Plates XVIII to XXII. These figures represent average speci- 

 mens of all now living (86) of the whole lot set for comparison. 

 Some were larger than those here shown and others a little smaller. 

 These trees were 3 years old from the seed when photographed and 

 have had only ordinary treatment. Photos. July 29, 1890, Hubbards- 

 ton, Mich. 



INOCULATION EXPERIMENT No. 4. 



XXV. Year 1890. Barnard tree inoculated in the fall of 1887 from a terminal 

 shoot on the healthy looking side of a diseased tree. Possible long 

 period of incubation. The top here shown was derived from the 

 inserted bud. Photo. January 28, 1891, Delaware. 



INOCULATION EXPERIMENT No. 5. 



XXVI. Year 1890. Two seedling trees. In Fig. 1 the growth from the inserted 

 bud was about 10 inches long, and more than one-half of its winter 

 buds had unfolded into feeble sprouts. Photo. October 30, 1890. 

 In Fig. 2 the spring foliage had fallen, but the same symptoms were 

 manifest. Photo. December 13, 1890, Washington, D. C. 



IMMUNITY. 



XXVII. Peach on plum. Trees budded on Mariana stock in August, 1888, 

 set November 7, 1889. Photos. October 18, 1890, Still Pond, Md. 

 Fig. 1, healthy and very thrifty. The white spot on the trunk 

 indicates the point of union between the plum stock and the peach 

 top. Fig. 2, tree badly stunted with yellowish and reddish foliage, 

 but no symptoms of yellows. The peach top had overgrown the 

 plum stock and there was a noticeable swelling just above the point 

 of union. 



XXVIII. Resisting power of old trees. Budded peach tree, 36 years old, farm 

 of James S. Harris, Still Pond, Md. The limb marked a? developed 

 symptoms of yellows in 1890. This tree has stood in a region of 

 diseased orchards for many years, but it was somewhat isolated and 

 well along in years before the disease appeared. Photo. October 

 18, 1890. The distance marked off on the trunk is 5 feet. 



II. PEACH ROSETTE. 



XXIX. Fig. 1, budded peach tree, 5 years old, and diseased in all parts by 

 the rosette. This tree was healthy in 1890. It first manifested 

 symptoms of disease in the spring of 1891, and at the time it was 

 photographed did not bear one healthy or full size leaf or nor- 



