224 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
the exact state of the tree at the time of spraying, photographic records 
are being made. It is hoped shortly to publish these results. 
The first thing one notices is the extraordinary resistance to spray 
damage shown by the young growths, so that at first sight, at any 
rate, it does not appear that the time of spraying need be influenced 
by fear of damage to the tree. These results agree with those found 
by Barker and Gimingham* in their work on Bordeaux spray injury. 
In their experiments they found that, so long as the cuticle of the 
leaf was uninjured mechanically previously to spraying, no damage 
followed ; but where such injury had occurred, whatever its cause, 
scorching of the leaf ensued. 
One may assume, therefore, that lime wash may be applied any 
time before the flowers actually open. If that proves to be the case 
the question arises at what precise period should lime spraying be 
done. The pests against which it is used are apple -sucker, apple aphis, 
and plum aphis. In average years the apple-sucker begins to hatch 
early in April, and continues to do so for a period of three weeks or so. 
Of the three apple aphids, Aphis fitchii, the stem and blossom aphis, 
and A. sorbi, the rosy aphis, usually give the most trouble. 
A. fitchii hatches early in April, attacks the flower buds, and does 
not cause leaf -curling, while A. sorbi hatches late in April and very 
soon causes leaf-curling. Now, if spraying is done at the beginning 
of April, so as to stop A. fitchii, it is very likely that there will not be 
a thick enough coat remaining on the tree to stop the hatching of 
A. sorbi, while if it is done towards the end of April to stop A. sorbi, 
A. fitchii will have already hatched and reached the flower buds, where 
the probability is that it will escape the effects of the spray. Where 
both forms are present, therefore, the position is difficult, and it is 
further complicated if apple-sucker is also present. 
Only experience can show the best time, though it is probable that 
the middle of April will prove most suitable. Similarly, the best time 
for plum -spraying will probably be just as the white of the flowers 
is beginning to show. 
Sprays Applied during the Dormant Season, 
Under this head come all those fluids which serve mainly for 
cleansing the tree from growth of lichens, moss, and algae. The practice 
of lime-washing trunks of fruit trees is an old one, and undoubtedly 
serves a useful purpose so far as it goes. 
One feels instinctively that a tree with a clean smooth bark should 
be a healthy tree, but instinct is not always a safe guide. One is 
perhaps too prone to look at the condition of the tree from the purely 
anthropomorphic view instead of from the point of view of the tree. 
Cleanliness in man is said to be next to godliness, and too often it is 
regarded as being next to fruit fulness in a tree, with a result that 
all kinds of caustic mixtures are used until the bark is smooth and 
* Barker and Gimingham, "The Action of Bordeaux Mixture on Plants " 
Ann. App. BioL vol. i. no. i. 
