BETTER FRUIT 



STATE ASSOCIATE EDITORS 



OREGON— C. I. Lewis. Horticulturist, ConaUls. 



WASHINGTON — Dr. A. L. Melander. EntomologlBt; 

 O. M. Morris. Horticulturist; W. S. Thoniber. Horticul- 

 turist. Pullman. 



COLORADO — C. P. Gillette. Director and Entomologist: 

 E. B. House. Chief of Department of Civil and TrrigatlOD 

 Engineering. State Agricultural ColleKe. Fort Collins. 



ARIZONA — E. P. Taj-lor, Horticulturist. Tucson. 



WISCONSIN — Dr. E. D. Ball. Director and Entomologist, 

 Madisr.n. 



MONTANA— O. B. Whipple. Horticulturist. Bozeman. 



CALIFORNIA — C. W. Woodworth. Entomologist, Berke- 

 ley; W. H. Volck. Entomologist. WatsonvUle; Leon D. 

 Batclielor. Horticulturist. Riverside. 



INDIANA— H. S. Jackson. Pathologist. Lafayette. 



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^'OLL'ME XIII 



P0RTI.AND, OuEGON, Septererer 1, 1918 



Number 3 



Pear-Blight Control in Rogue River Valley, Oregon 



PEAR blight (bacilliLS amylovorous) 

 made its first appearance in the 

 Rogue River Valley in the season 

 of 1907. For two or three seasons this 

 disease was regarded by the growers 

 as "Sour Sa])" and very little attention 

 was given it. In 1908 and 1909 this 

 so-called "Sour-Sap" trouble became 

 more serious and made its appearance 

 in many parts of the valley. Some of 

 the growers at this time undertook to 

 cure this trouble by splitting the bark 

 of the infected trees. This procedure 

 caused greater trouble, as it merely 

 spread the bacteria from infected parts 

 to healthy tissues and many trees w^ere 

 lost as a result of such practice. 



About this time some of the pro- 

 gressive fruit growers of the valley pe- 

 titioned the Department of Agriculture 

 for assistance in handling this disease. 

 Mr. P. J. O'Gara was detailed for this 

 work, and after making an extensive 

 investigation was employed by Jackson 

 County to assist in educating the grow- 

 ers along the proper methods of con- 

 trolling pear blight. This so-called 

 "Sour-Sap" trouble turned out to be the 

 most dreaded disease of all pomaceous 

 fruits — Pear and Apple Blight. 



Practically all commercial varieties 

 of pears have been ravaged by this 

 disease. Of course, some varieties are 

 more susceptible. The Bosc, Howell, 

 Anjou, Bartlett, Comice and Winter 

 Nelis show susceptibility in about the 

 order named. Keifer stock, that was 

 formerly supposed to be resistant to 

 blight, has proved susceptible to more 

 or less extent. In fact we have no com- 

 mercial varieties growing in the Rogue 

 River Valley that are immune or either 

 highly resistant. 



Spitzenberg apples head the list for 

 susceptible apple varieties. For several 

 years Newtowns ajipeared to be more 

 or less resistant, but at the present 

 writing Newtowns blight very severely 

 if control measures are not scrupu- 

 lously followed. Winesaps are very re- 

 sistant an<l very little infection is 

 found in this variety. 



During the early part of the cam- 

 paign, for the control of bligiit a large 

 force of inspectors were employed by 

 the county. The orchards were pa- 

 trolled by inspectors and blight cutters 

 and an effort was made to keep all the 



By C. C. Gate, County Pathologist, Medford, Oregon 



infected parts cut out. At that time the 

 work and attention of inspectors and 

 blight cutters was directed toward the 

 trunk and branches of the trees. As 

 many as fifteen inspectors were em- 

 ployed by the county to prosecute this 

 work. The orchardists and inspectors 

 worked very vigorously, and to show 

 how thoroughly this work was done 

 many times tree-to-tree inspections in 

 large orchards revealed no cases of 

 "hold-over" blight. Nevertheless, seri- 

 ous infections would develop during 

 the succeeding season, and at that time 

 it was impossible to know the origina- 

 tion of the source of infection. On 

 account of the repetition of severe out- 

 breaks of blight following such careful 

 inspections and elimination of all 

 visible "hold-overs" the orchardists in 

 some sections became discouraged with 

 this fight against pear blight and it 

 became necessary to develop new meth- 

 ods of control in order to keep the 

 orchardists in the orchard business. 



Cornice, showing trcatnu-iU of infection in 

 trunk and roots. 



About two years ago we started to 

 make investigations upon the matter of 

 "hold-over" sources and also to inves- 

 tigate new methods of control and pre- 

 vention. As a direct result of our in- 

 vestigation for "hold-over" sources we 

 found that the root systems of many 

 trees were infected and that certain in- 

 sects were carrying the disease from 

 the roots to the blossoms at blossoming 

 time. Then we started a campaign of 

 root inspection and in the older 

 orchard districts where blight has been 

 most serious for a number of years, 

 practically every tree in the district 

 was examined about the roots and all 

 cases of infection were removed. This 

 operation naturally called for a lot of 

 work in excavating about the roots of 

 the trees, but the orchardists appreci- 

 ated the value of the work and spent a 

 great deal of time and money in mak- 

 ing this cleanup in connection with a 

 very careful cleanup in the aerial part 

 of the trees. As a result of this work 

 we have learned by experience that 

 blight can be very effectively controlled 

 and that it could not be controlled by 

 confining our efforts to the top of the 

 trees. A great deal of effort and money 

 has been expended by the orchardists 

 making a very thorough cleanup in the 

 tops of the trees and then only to ex- 

 perience a repetition of infections just 

 as serious as if no cleanup had been 

 made. This was due to the fact that 

 we left many sources of "hold-over" 

 hidden away in the root system. 



In excavating around the roots of the 

 trees we have found many species of 

 insects that may be responsible for 

 spreading blight from the roots to the 

 tops of the trees. Insects most fre- 

 quently found about the base of the in- 

 fected trees instrumental in spreading 

 the blight are the common click beetles. 

 We found over 200 of these click 

 beetles around the base of a small tree 

 not over four inches in diameter that 

 was infected with blight below the sur- 

 face of the soil. The accompanying 

 photograph of insects will give some 

 idea as to how these insects will col- 

 lect about the blight-infecled roots. 

 These insects were taken from the base 

 of one tree during blossoming lime. 

 These beetles would be found feeding 

 in the opening blossoms and are found 



