THE MONTHLY BULLETIN. 243 



PLANT DISEASES. 



Pear Blight. 



The bacterial disease known as pear blight continues to be destructive 

 and the work of cutting off the dead and blackened twigs and areas 

 should be continued. At the time the organism ceases to spread rapidly 

 there is a noticeable line separating the dead from the comparatively 

 healthy tissues. In many cases the bark is broken and there is a 

 gimmy exudation. Sterilize the wounds and pruning tools with cor- 

 rosive sublimate 1 to 1000 and cut off the diseased portions below any 

 signs of infection. 



'o* 



Lemon Gummosis. 



The work of H. S. Fawcett^ on the disease known as gummosis of the 

 lemon has demonstrated that the disease is of a fungous nature caused 

 by two fungi, the gray fungus and the brown rot fungus, both of which 

 cause the fruit to rot in the citrus orchard and in the packing-house. 

 The gray fungus causes the killing of the outer layer of bark much in 

 advance of the inner, and in which there is some softening of the bark, 

 while the brown rot fungus causes the killing of the inner bark to lag 

 slightly behind that of the outer and in which the bark remains hard 

 as the area of infection enlarges. Mr. Fawcett has also demonstrated 

 that the best treatment for this disease in the case of the gray fungus 

 is to scrape oft' the outer dead bark an inch or so beyond the line of 

 visible infection and paint the entire trunk with the bordeaux paste. 

 In treating the brown rot gummosis, cut out the bark an inch or so 

 beyond the discolored line before applying the mixture. The entire 

 surface is then covered with the fungicide. If these areas are treated 

 before infection has spread to any extent much work and money can 

 be saved. Mr. Fawcett also advises the cutting back more or less 

 severely on the side where the bark has been killed if this area is large. 

 The bordeaux paste is made by dissolving one pound of copper sulphate 

 (bluestone) in one gallon of water in a wooden or earthen vessel, two 

 pounds of unslaked lime slaked in one half gallon of water; stir 

 together when cool. This makes a light blue mixture about the con- 

 sistenc}^ of whitewash. The paste deteriorates with age so that fresh 

 mixture should be made every day or so. The paste can be applied with 

 a large brush. 



Dodder. 



Alfalfa dodder is a thread-like yellowish vine which is parasitic upon 

 alfalfa. Badly affected areas in the alfalfa field should be allowed to 

 dry out for some time, in which case the dodder may often be killed 

 without destroying the alfalfa. Often the dodder infested areas are 

 burned over. It is sometimes necessar}^ to plow up badly infested fields 

 and replant later. 



^Vol. II, Monthly Bulletin, State Commission of Horticulture, page 601. 



