DISEASES AND PESTS OF PLANTS. 13 



should be made to determine whether root, crown, or serious trunk-infection exist. 

 The condition of the foliage is often of value in indicating the presence of such cases, 

 while proper inspection of the parts below ground is difficult or impossible after the 

 ground freezes. Trees which are to be taken out should be marked at this stage 

 in order that work may not subsequently be wasted on them. The cutting-out of 

 the cankers is best done when the leaves are off, as they can then be seen better. 

 The dead leaves often persist for a considerable time on the blighted twigs, and if 

 the work is begun as soon as the leaves fall, these persistent ones facilitate the find- 

 ing of some of the blight. The extent of injury which makes it preferable to take a 

 tree out rather than to treat it depends very largely upon the grower himself. If 

 sufficient skilled work can lie spent on them, bad cases of body-blight and even of 

 root-blight may be saved. Even trees completely girdled may have the diseased parts 

 cut away and the means for sai>flow re-established by bridge-grafts. In this connec- 

 tion, however, it is to be noted that unsuccessful work is just so much labour thrown 

 away, and it is probably best for the average grower not to attempt to treat any 

 cases of the disease at or below the ground-line, but to take out the tree. When 

 cutting during very cold weather some growers have considered it unnecessary to 

 disinfect the cuts. This, however, cannot be recommended, as it is not free from 

 risk. It is quite true that trees in the dormant condition are much less susceptible 

 to infection, but the blight bacillus can survive without serious injury temperatures 

 as low as 40 Fahr. The only permissible exception would Ite when the temperature 

 is so low as to solidify the aqueous solution of corrosive sublimate before it can be 

 applied, and even in such cases it would probably be wise to go over these wounds 

 subsequently with a disinfectant. Even if every care is exercised, it is not sufficient 

 to do thorough work and then leave it. No blight-cutler is expert enough to remove, 

 at one cutting, every case of " hold-over " in an orchard of any size, if the blight 

 has been at all severe. The grower should go over his trees at intervals, when the 

 light is good, in order to detect and remove anything that has been missed. This is 

 especially necessary after the sap has begun to flow, as missed "hold-overs" or 

 imperfect work may often be revealed at this time by their moist appearance. A 

 very careful inspection should be made just before blossoming-time, as much blossom- 

 infection may be saved by the detection of an active canker at this time. A careful 

 watch should also be kept for the first appearance of blossom-blight. If this should 

 occur in spots, it is often possible to trace the infection to some centrally placed 

 "hold-over" which has been missed. The removal of this may still prevent some 

 infection. Where there is only a little blossom-blight it may be removed by cutting 

 off the infected spurs, but for this to be successful it is essential that the disease 

 should not have passed beyond the spur into the branch bearing it, or, if so, that 

 the limits of the infection be accurately determined and the cut made accordingly. 

 It very frequently happens, also, that the disease dies out in the blossom, or the spur, 

 without extending farther. For these reasons, if blossom-infection is at all abundant, 

 it is best to leave it for the time being, watch it very closely, and cut out at once 

 any infection that begins to "move." Twig-blight should also be cut out as it 

 appears. Where the work in the dormant season has been thorough, the extent of 

 blossom and twig infection should not be too great to permit of its prompt removal. 

 Where, for any reason, however, the infections are very numerous, many of them 

 may dry up and apparently die out before they can be attended to. The question 

 now is, whether, especially if the season has reached late summer, such dried-up 

 infections may be left until the clean-up in the dormant season. There is no doubt 

 that successful results have been obtained in certain districts in certain seasons by 

 so doing, and with greater economy since the pressure of work is greater at this 

 time, and the loss of fruit from working in the trees at this time may be considerable. 

 More care is also necessary over the work, and there is greater wastage of tree-tissue 

 than in work done during the dormant season. At the same time, especially in 

 irrigated districts, there is a danger of many apparently dried-up infections starting 



