PEAR GROWING IN CALIFORNIA. 353 



Bartlett, Flemish Beauty, and Forelle, will not be lessened by a resistant 

 root system but with the fight against the disease confined to the por- 

 tions of trees above ground much of the expense now met with will be 

 eliminated. The Japanese root, while far more resistant than the 

 French, is not entirely immune and the search for something still better 

 is now going on. For taking the initiative in this important investiga- 

 tion, California owes much to her sister state, Oregon, which under the 

 direct and able supervision of F. C. Reimer, has conducted most com- 

 prehensive and carefully planned experiments with more than 500 varie- 

 ties and 30 species of pears at the Southern Oregon Experiment Station 



at Talent. It was the writer's privilege 

 to visit at this station recently, where, 

 in the absence of Professor Reimer, Mr. 

 A. C. McCormick described in detail the 

 various experiments. There it has 

 been proven that, under the conditions 

 existing in the Rogue River Valley 

 of Oregon, certain species and varie- 

 ties are practically immune from blight. 

 In fact, one species upon which 210 

 inoculations on eight different dates 

 have been made has never developed a 

 single case of blight* while alongside, 

 susceptible varieties inoculated at the 

 same time with the same cultures have 

 always developed the disease. This 

 species is known as Pyrus ussuriensis. 

 Professor Reimer who made a special 

 trip in 1917, to Japan, Korea, Manchu- 

 ria and China to study this and other 

 Oriental pears, especially the blight 

 resisting types, states regarding it as 



FIG. 150. Leaf of Pyrus ussuriensis. /> 11 



' ' This species appears to be immune to pear blight, at least under the 

 conditions in southern Oregon. 



"The season of 1916 has been a favorable one for the development 

 of pear blight. The disease has been unusually severe in many of the 

 orchards, causing the loss of many trees. During the season young 

 vigorous trees of this species have been inoculated 210 times on eight 

 different dates. One hundred and five of these inoculations were made 

 in the tips of young vigorous-growing shoots, 85 in branches less than 

 one year old, and 20 in the trunk of a two-year-old tree. 



"Not a single case of blight developed in any of these. Check trees 

 of many of the other species and varieties inoculated at the same time, 

 in the same manner, and with the same lots of bacteria, blighted vigor- 

 ously. This is the only species which so far has proved immune in our 

 work. It is a native of northern China, Manchuria and eastern 

 Siberia, and withstands lower temperatures than any other known 



*Address by Professor F. C. Reimer before the Pacific Coast Association of 

 Nurserymen. 



135 



