PEAR BLIGHT AND ITS TREATMENT 261 



growth and fruit show whether proper moisture needs are met or not. 

 Early pears are advanced in development by irrigation in some parts of 

 the State, and this is an important factor in their value. 



BLIGHT OF THE PEAR 



The pear blight appeared in the San Joaquin Valley about 1900. 

 In 1904, after having nearly wiped out bearing trees in the southern 

 counties of the San Joaquin Valley the disease began to devastate the 

 orchards along the Sacramento River through the vast area of rich 

 valley land which it traverses and on which is situated our most ex- 

 tensive pear acreage. In 1905 resolute warfare was made upon the 

 blight, with a large appropriation of State funds, by the plant disease 

 experts of the United States Department of Agriculture and of the 

 California Agricultural Experiment Station, with the assistance of the 

 local horticultural authorities. It was probably the greatest campaign 

 ever made against a single tree disease although some insect warfares 

 have been greater. The outlines of the plans followed and the results 

 attained are to be found in the publications of the institutions engaged.* 



In a later chapter on Diseases of Trees and Vines, an outline of 

 procedure against pear blight will be given. It is apprehended that 

 neither paying crops nor living trees can be counted upon in the future 

 unless the disease is successfully kept under control by successful 

 fighting or by recourse to some form of natural immunity which can be 

 discovered or developed by plant breeding. It is probable that pears 

 can not be grown in the future as cheaply and profitably as in the 

 past and there is a certain amount of bravery or daring in pear invest- 

 ments at the present time. It is encouraging, however, to note that in 

 California the disease shows signs of relaxing the virulence which 

 characterized its first attacks and it is reasonable to believe that here as 

 elsewhere it may be possible to have the blight and pears also.f The 

 reader must keep himself continually of the various phases of the 

 problem as they will arise, by careful study of California horticultural 

 journals and of later publications from the official sources which have 

 been indicated. 



The very exuberance of the pear in California seems to increase the 

 virulence of the blight. The long growing season with its continual 

 production of new soft tissue, the unseasonable bloom which attracts 

 bees to bring new supplies of blight germs, the break of new shoots 

 from root, trunk and main branches all these make the tree subject 

 to repeated renewals of the disease in all its most vulnerable parts. How 

 far growth can be repressed by scant cultivation or by summer prun- 

 ing ; how far suppression of later shoots and blooms is practicable and 

 whether the tree can be depleted so that it can only make fair sized 

 fruit and no surplus soft tissue for blight invasion all these are cul- 

 tural problems which make pear growing very interesting to the enquir- 



*Reports of the California Commissioners of Horticulture, 1901 to 1906, including Reports 

 on California Fruit Growers' Conventions for 1905-6-7, Horticultural Commissioner, Sacra- 

 mento. Report of Plant Pathologist, University Experiment Station, Berkeley, 1906 and 1908. 



fThe character of such a fight and what it costs is graphically portrayed by E. A. Gam- 

 mon in the Report of California Fruit Growers' Convention of 1909, and in Pacific Rural 

 Press, June 22, 1910. 



