364 PEAR GROWING IN CALIFORNIA. 



NEW METHOD OF BLIGHT CONTROL A POSSIBLE SUCCESS. 



Fig. 158 illustrates a type of tree, thousands of which have been 

 uprooted because of complete girdling by blight. An examination of 

 the picture will show that from a point just below the handkerchief 

 on the main central branch, to the ground, and also for a considerable 

 height on the other two main branches the bark has been scraped 

 away. From the ground to the handkerchief is about 5 feet and for 

 this entire distance blight had completely girdled the tree. By scrap- 

 ing away the outside bark, removing just as little of it as possible, 

 and applying a concentrated Bordeaux paste the tree was saved and 

 the cracks seen in the bark are due to the development of the healthy 

 growing layers underneath. 



Work of this nature has been done for the past year in the Hayward 

 Reed orchard near Sacramento, and, according to Mr. Reed, trees which 

 at one time were considered hopeless cases can be saved providing 

 that the bark has not been killed when the infection is discovered, and 

 providing that prompt measures are taken in scraping away the out- 

 side bark from every square inch of diseased surface, treating same 

 with Bordeaux paste or concentrated lime-sulphur. Prior to the appli- 

 cation of either of these the wound should also be disinfected with 

 corrosive sublimate. 



Experiments were made without the use of Bordeaux or lime- 

 sulphur, with the idea that exposure to the sunlight and air would kill 

 the bacteria. Some cases treated in this manner recovered, but in 

 most cases the disease was only temporarily checked. The hundreds 

 of trees saved after the application of either Bordeaux or lime-sulphur 

 indicate that there is a possibility of very successful control work 

 along the lines suggested. The method is not recommended except 

 for trial, because of the fact that insufficient work has been done to 

 justify such a recommendation, and hasty conclusions might lead to 

 serious consequences. 



PEAR CANKER. 



In Vol. I, No. 7, of the Monthly Bulletin of the California State 

 Commission of Horticulture, Professor H. S. Fawcett described a 

 canker of pears from material that he received from El Dorado County. 

 Apparently this canker was due to the fungus Sphaeropsis malorum. 

 The following is quoted from his article: 



"In the center of the affected spot is a small circle of cracked bark. 

 This is surrounded by larger elliptical rings of cracked bark with the 

 longer axis of the ellipse in the direction of the branch. Professor 

 R. E. Smith refers to this canker under the head of "Curly Bark of 

 Pear" (Bulletin 218, California Experiment Station). Cankers due 

 to the fungus Sphaeropsis malorum have often been reported on apple, 

 quince and pear trees in the .Eastern states. The same fungus also 

 causes a rotting of the fruits known as black rot. ' ' Removal of cankers 

 as in pear blight is recommended. 



Cankers may also be due to species of Nectria which have been 

 found attacking apple trees with the formation of similar cankers. 



146 



