1630 



ENCYCLOPEDIA OP PRACTICAL HORTICULTURE 



water supply, and it may l^e said that 

 tlie death rate is very largely an index 

 of its condition. In the same sense, the 

 attention given the sanitary conditions 

 of the orchards of any community is an 

 index of the death rate of the orchards. 

 Of course, the cutting out of hold-over 

 blight must be done, not alone in a single 

 orchard, but the work should be general 

 and thorough throughout the entire area, 

 such as an inclosed valley or even, for 

 better work, an entire state. Complete 

 eradication of pear blight from such a 

 large area is, of course, very difficult. 

 However, the fewer hold-over cases that 

 may be missed will result in fewer cases 

 of infection later in the spring and sum- 

 mer. As may be seen by referring to the 

 factors influencing the disease, the pres- 

 ence of the germ is of primary impor- 

 tance. If the pear-blight germ is not 

 present in the orchards there can be no 

 blight, no matter what the weather con- 

 ditions may be. The orchards of Cali- 

 fornia existed for 25 years with varying 

 climatic conditions, and no one ever 

 heard of blight in those orchards until 

 the germ was introduced. 



The regular development of the disease 

 has been pointed out by which it runs 

 down on one side of the limb or body and 

 not on the other; this often leads to fail- 

 ures in eradicating the blight from or- 

 chards. While the disease in the top is 

 very easy to handle and anyone who 

 looks at all closely can not only detect 

 it but can readily remove the infected 

 branches, the disease on the body and 

 in the root system is not only hard to 

 see, but is often difficult to find, espe- 

 cially on old trees where the crowns and 

 bodies are covered with rough bark. It 

 may be said here that the removal and 

 the detection of hold-over in pear trees is 

 not nearly so difficult as in the case of 

 the apple and the quince The Spitzen- 

 burg apple is probably the worst variety, 

 if not the worst species of the pome fam- 

 ily, in which to detect hold-over and to 

 effectively remove it. 



The gum exudate, when it is present, 

 gives a clue to many otherwise obscure 

 cases. However, in cases of late fall and 



summer infections, the lesions may be so 

 small as to produce no exudate or give 

 any other evidence of infection. A dead 

 water-sprout or fruit spur, no matter 

 how tiny it may be, leads to the detec- 

 tion of a case. Sometimes these have 

 been broken off in cultivation or care- 

 lessly cut off without following up the 

 infection at the base. Very often a water- 

 sprout which has come up from the root 

 system at some distance from the base 

 of the tree becomes infected, and is later 

 removed by cultivation; but the infection 

 passes on up the infected root, finally 

 involving the entire root system. Some- 

 times there is infection without a water- 

 sprout or bud at all, and such cases are 

 the hardest to detect unless some ooze 

 has appeared. Such infections come 

 about through insect punctures and 

 growth cracks by means of which the 

 germ has been introduced. Where there 

 is a large amount of blight to be removed 

 from the orchard, necessitating a great 

 deal of labor, it has proven necessary in 

 every case to go over the orchard crit- 

 ically, or perhaps we may say leisurely, 

 on a dry, sunshiny day when there is 

 good light, and find the few cases that 

 have been missed on the first inspection. 

 No matter how thorough the work, this 

 careful method of inspection has proved 

 extremely important. Not only should 

 the work be inspected immediately fol- 

 lowing the general clean-up, but someane 

 else with keen, well-trained eyes should 

 look over the trees several times during 

 the winter. A special effort should be 

 made to find out when there is a new 

 exudation. This may follow any warm, 

 mild spell in the winter, when there is 

 a wide range between the day and night 

 temperature. Such conditions are known 

 to affect the flow of sap in the sugar 

 maple and other trees. A final inspec- 

 tion should be made just before blossom- 

 ing time to catch any hold-over blight 

 the last moment, in case it has been over- 

 looked before. 



After the blossoming period has passed 

 so that the blight has had time to de- 

 velop, if an area of blight infection is 

 found in the orchard, careful examina- 



