THE PEARS OF NEW YORK II3 



all but impossible in the average orchard. Sometimes, without doubt, 

 the virulency of the disease is lessened. Possibly, if all the recommenda- 

 tions of plant pathologists could be put in practice, pear-growers would 

 more often succeed in keeping blight down, but the necessary sanitary 

 measures require such watchful care and so great an expense that few 

 pear-growers can carry out the program for controlling this disease. Of 

 those who have studied methods of control and have given advice on 

 the subject, Hesler and Whetzel ' are as reliable as any and we quote here- 

 with their recommendations: 



" In attempting to control fire-blight, the following important points 

 should be borne in mind: (i) That the disease is caused by bacteria which 

 gain entrance to the host tissues only through wounds, or ptmctures by 

 insects, into succulent, rapidly growing tissues, or through the nectaries 

 of the blossoms. (2) That insects of several kinds are the usual agents 

 of innoculation. (3) That practically all pome fruit-growing sections in 

 North America are infested, and therefore there is always a source from 

 which the bacteria may be disseminated. (4) That all known varieties of 

 the hosts, on which the blight organism occurs, are more or less susceptible; 

 while some show resistance, none are wholly immune. Therefore control 

 consists chiefly in the elimination of the pathogene from the infected trees. 

 This is accomplished by a strict application of the following operations: 



(a) Inspect all pear trees in the autiimn and again in the early spring before 

 the blossoms open, and cut out and treat all cankers in the body and main 

 limbs. With a sharp knife, or draw-shave, remove all the diseased tissue, 

 wash the wound with corrosive sublimate (one tablet to one pint of water), 

 and, when dry, paint the wound with coal-tar or lead paint, preferably 

 the former. The wound-dressing will need renewal every year or so. 



(b) Throughout the summer, beginning with the fall of blossoms, make 

 an inspection every few days of the young trees. Break out the blighted 

 spurs and cut out diseased twigs, making the cut at least six inches below 

 the diseased portion. Disinfect the cuts with corrosive sublimate, (c) 

 Remove all watersprouts from the trees two or three times during the 

 season, (d) In the nursery remove the blossom-buds, particularly of the 

 quinces. Here inspection must be frequent, particularly in susceptible 

 stock, in order to keep the disease under control. It is often necessary to 

 inspect certain blocks daily, the diseased twigs being cut out as soon as 

 observed. When budded stock of the first year becomes affected, the trees 

 should be dug out, since cutting below the diseased area causes the trunk 

 of the young tree to be crooked and therefore not marketable, (e) Control 

 the insects. The real point of attack lies in this phase of the problem." 



' Hesler and Whetzel. Manual of Fruit Diseases 32^^31. 1917. 



