312 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



disease is one of those visitations that come about in some indefinable 

 way without a definite reason for its appearance. 



Trees that have been sprayed in Mortlake Orchard, carefully pruned — 

 I know you would say this is a laboratory experiment — all dead parts cut 

 away, twice sprayed during the winter, along with the surrounding 

 ground, with this sulphate of copper solution, pure and simple, have been 

 more free from scab than surrounding trees that have been sprayed 

 in the orthodox manner, beginning with soft foliage when you cannot 

 use Bordeaux mixture except in its diluted condition. If you begin 

 on young foliage you are reduced to two things : either use Bordeaux 

 mixture in such a diluted condition that you know in your own heart 

 it does no good, or use it stronger, and you are equally convinced it 

 will generally burn the foliage. 



Finally, in connection with sprays. We speak of "sprays," and 

 unfortunately that up to the present is far from the ideal. The ideal is 

 water vapour, the kind of thing that comes from the spout of a kettle of 

 boiling water. If we could have that it would settle down all over the 

 upper side and under side, and remain, if you stop spraying at the right 

 moment ; but all our spraying machines, even the very best of them, send 

 out the water in obvious drops to begin with. These drops unfortunately 

 have a tendency, as you know in the case of rain on a window, to run 

 together and form larger drops ; that is why you do not get your leaf 

 equally sprayed all over. The longer you spray the worse it becomes. 

 That is, the drops are larger, and a less surface of the leaf is covered ; 

 and it is important to remember that the water does nothing ; it is the 

 stuff in solution with the water. Unless the spraying material remains 

 on the tree, and the water evaporates, leaving whatever it may have 

 held, the spraying is a failure ; and it is very important to know 

 when to cease spraying. The longer you spray the less material you 

 get on the leaves ; and then if you conscientiously, and without any bias, 

 examine any tree that has been carefully sprayed you will see that in 

 90 per cent, the upper surface of the leaf has ten times more stuff on 

 it than the underside. There are all sorts of reasons for that. One 

 important reason is, as a rule, although the upper surface of the leaf 

 may be almost as smooth as glass, as in the case of ivy, the under 

 surface is not. It may look smooth, but if you magnify it you will find 

 it is covered with a more or less dense mass of hair, or very fine silk, and 

 the spray never touches it. It is rather important that the under surface 

 of the leaf should be sprayed — in fact it is very important — rather than 

 the upper surface of the leaf. That is the difficulty we are in. Of course 

 that is a point for some manufacturer to solve, to get a finer spray. If 

 we could get a spray similar to London fog there would be some hope 

 that it would settle down equally over both the upper and lower surfaces 

 of the foliage. 



The Chairman : I now propose to ask Mr. Wilks to read 

 Mr. Getting's paper, and at its conclusion I will call on anyone who 

 wishes to discuss the matter. 



