WHITE-PINE BLISTER RUST. 87 



phur in parallel experiments. The following statement has reference 

 to spraying that was done every two weeks through the summer: 



It was realized that the spray would ha\'e to be applied to the under sides of the 

 leaves to be effecti\'e, and though this was done as thoroughly as possible in our work, it 

 must be admitted that it takes so much time and care that satisfactory- sprajing of this 

 kind would be out of the question in a commercial way. Owing to frequent rains dur- 

 ing the summer, the best results were not obtained from this work, but even allo\\ing 

 for this it was certain that, though the rust can be greatly reduced by spraying, it can 

 not be controlled sufficiently to prevent the spread of infection. Consequently, what- 

 ever value sprajdng methods may have as a means of protecting indi\idual planta- 

 tions, they are likely to be of little use in combating the disease as a national pest. In 

 this connection, it has been suggested by the Dominion Botanist that since spraying 

 will not completely control the rust, it may work a positi^•e harm by keeping the in- 

 fected leaves longer on the bushes in the fall, and thus materially extend the period 

 during which infection of the pine may take place, pro\idijig, of course, that the in- 

 fection of pines is possible throughout the whole season, 



Stoddard, in 1918 (23), carried out a spraying test in Connecticut, 

 with the following results : 



Spraying experiments for the control of the bHster rust were conducted on red and 

 black ciu-rants. Results were nearly negati^'e on red currants because of lack of in- 

 fection. On black currants spraying gave nearly complete control thi'oughout the 

 season. However, such careful and frequent spra>dng had to be done that it is not 

 considered to be a practical method of control . 



No experiments have been made in the spraying of pines, as it has 

 appeared useless in larger trees where the infections have occurred. 

 Seedlings in seed beds of nurseries may perhaps be protected from in- 

 fection by spraying, as has been suggested b}^ Clinton and McCormick 

 (14) . It should be well tested under extreme conditions (106) . 



CLOSE PASTURING OF RIBES. 



The use of animals to feed on the leaves of Ribes is feasible if the 

 area is pastured heavily until well cleaned up. Sheep are very close 

 feeders and undoubtedly can be thus utilized (23, p. 7). Goats are 

 the most promising animals for the purpose, however, as they are 

 omnivorous feeders. This method can be recommended only for 

 areas where small pines are absent or too few to be of value. 



REMOVAL OF DISEASED PARTS AND DISEASED PLANTS OF RIBES. 



The removal of the infected leaves has been attempted in a few 

 lots of Ribes nigruin in nurseries, but it is costly and merely palliative 

 in that it is usually only postponing more drastic measures. The 

 cutting back of infected Ribes bushes has been tested in a few 

 instances, but like the plucking of the leaves, it is usually unsatis- 

 factory, since the bush remains to take infection another season. 



The removal of diseased plants only of Ribes is unsatisfactory, 

 as it has been found that it requires repeated visits through the season 

 for the removal of plants which have developed the disease since 



