CONFERENCE ON SPRAYING OF FRUIT TREES. 329 



taking into account the fact that a certain number of the eggs are 

 normally infertile. 



With regard generally to spraying for insects, if we are going to do any 

 good, the point we have to aim at is the destruction of the young insects 

 before they do damage. Many do not see the young winter- moth cater- 

 pillars. Why not ? They are quite easily seen. If you, knowing the 

 time the creatures appear, see them here and there or find there are 

 great numbers, then set to work and spray with some fluid that will 

 destroy them ; but do not go and spray a plantation because the caterpillars 

 may come. They do not come ; they are there or not there ; and the 

 spraying must be done to kill the creatures, not to try to prevent their 

 coming. The spraying of fruit trees for these and other insects at the 

 best can only do some good ; you will in any case do a great deal more good 

 by trapping many insects and preventing them from laying their eggs. 



Some of the chief washes I shall refer to very briefly. With the 

 exception of tobacco and quassia, all the chemical washes that are used 

 (whether purchased ready-mixed or made at home) do a certain amount of 

 damage to trees. You may kill the creature doing the harm, but in doing 

 so you will do a certain amount of harm to the trees, and if you go on 

 year after year with these washes you give the tree a hard set-back that 

 it will take many years to recover from. You want to cut the washing 

 down as low as you possibly can on account of the damage which it does, 

 on account of the cost, in many cases on account of the uncertainty of 

 the action ; and lastly, I am quite sure, there is an amount of damage 

 done by the process of washing, for the mere taking of the machines 

 through the plantation does an enormous amount of harm, unless it is 

 done very carefully ; so that altogether there are many disadvantages in 

 spraying. Yet we must acknowledge that unless it is done judiciously fruit- 

 growing will not properly flourish. 



The winter washes, then, are primarily for one purpose, namely, 

 cleansing trees. If you have a clean plantation it is advisable to keep it 

 clean. If the trees become covered with green algae, spray them with a 

 winter wash. For cleansing trees I do not think it matters which one you 

 use ; one is just as good as another. Assuming we have very old trees, 

 such as are found in some of the cider orchards in the West of England, 

 it will not do to spray the trees every now and again. You will have to 

 winter wash perhaps for five, six, or seven years before you can remove all 

 the foreign growth accumulated on the trees, and then, having cleansed 

 them, you can fall back and treat them once every two or three years. 

 But if you treat fruit trees with the strong caustic washes year after year 

 I believe you do the trees as much harm as the foreign growths. Paraffin 

 in particular, if used continuously, will produce very distinct appearances 

 on the bark of the tree, and will do a great deal of harm. If you want 

 merely to cleanse the trees use any of the washes that are advertised, or 

 make one yourself, which is usually cheaper ; but if you see the trees are 

 covered with mussel scale, or infested, we will say, with the apple sucker, 

 or if the pear trees are damaged year by year with the pear-leaf blister 

 mite, which attacks the fruit as well, then you must modify the form of 

 winter wash you are going to use according to the pest you want to 

 destroy. For instance, if you have the mussel scale I would suggest for 



