SPRAYING CALENDAR 105 



late in March or early in April in the case of plum 

 trees, and somewhat later in April in the case of 

 apples, and, if the winter washing has been delayed 

 till a late date in March, which is often the case, the 

 spraying of plums for the destruction of aphis will 

 generally be unnecessary. 



If winter washing and spraying in spring have been 

 done thoroughly, spraying in summer may usually be 

 dispensed with, without any material detriment to the 

 trees ; indeed, it is only as regards winter washing 

 that universal adoption should be insisted upon. 

 Apart from the consideration of the direct action of 

 a winter wash in destroying various pests which 

 are probably present, moss, lichen and dead bark 

 must always accumulate, and the freer trees are kept 

 from these, the healthier they will be, and the less 

 will be the opportunities afforded for insects to 

 flourish on them. But even winter washing need not 

 be done every year, and a thorough application of 

 a sufficiently strong wash once in every two or three 

 years should be sufficient ; indeed, in the neighbour- 

 hood of manufacturing districts, where the impurities 

 in the air are hostile to surface growth on trees, an 

 even less frequent application may be sufficient. 



It is in this provisional sense, therefore, that 

 growers should make use of the following calendar, 

 nor is there much fear of their attempting to follow it 

 in its entirety, if they wish to make any profit out of 

 their fruit. It is scarcely necessary, however, to say 

 that the calendar should not be used alone, without 

 referring to what has been said in the previous part 

 of this work, both as regards the pest to be destroyed. 



