CONFERENCE ON SPRAYING OF FRUIT TREES. 



339 



solution of tobacco made according to Mr. Pickering's formula ; * and not 

 only was it successful against apple sucker, but equally so against aphides 

 and caterpillars wherever it touched them. I have no hesitation in 

 recommending this wash most strongly to growers for spring use, as I 

 consider it the best one I have ever found, the only drawback being the 

 price of tobacco ; and I consider that fruit growers should unite in strongly 

 urging the Board of Agriculture to bring pressure on Parliament, or else 

 apply that pressure direct themselves, to enable some scheme to be put 

 forward to relieve such tobacco from the duty which is the bulk of its 

 cost. For red spider on gooseberries where they are very tender and it is 

 not considered advisable to use paraffin, liver of sulphur is a most ex- 

 cellent remedy; but it must be remembered that for the destruction of 

 this pest one spraying is not sufficient, for the reason that, if the weather 

 is not bright, some of the insects may be in the clods and not up in the 

 trees, and also that the hatching of the eggs extends over a rather long 

 period, and if one batch is killed there may be in a few days another lot 

 hatched out 



So much for the foes we can kill in open fight. Several, like the 

 weevils, work largely at night, or, like many of the caterpillars, are 

 impossible to get at owing to leaf curling ; so that we must adopt another 

 method for them, and that is, to poison their food. For this we require 

 something which may be spread in a very thin deposit on all the leaves 

 and which may be sufficiently strong to poison the insect without burning 

 the leaves themselves. We find such a substance in the compounds of 

 arsenic which, diluted with water and in this way finely divided, are 

 some of them also not hurtful to trees. 



London purple used to be largely used, but has been given up as 

 very clumsy and dangerous, and now Paris green t and lead arsenate are 

 the largely used washes — the former in cases in which it is desired soon to 

 be washed off, as on trees over bush fruit, and the latter where it 

 is desired to stick on as long as possible, and there is no danger of 

 poisoning any under crop. For using both, the fruit grower cannot do 

 better than obtain them in paste form, as is now possible, in which condition 

 they may be readily mixed with cold water, reducing all risk of accidental 

 poisoning of mixers and sprayers, and also ensuring the correct propor- 

 tions. It has been proved by experiment now, however, that no lime is 

 needed in using Paris green, and that the risk of burning the foliage is 

 far greater with than without it. 



These sprays, however, in contradistinction to those for aphides, 

 sucker, and red spider, must not be applied in a powerful stream, but in a 

 light mist-spray, otherwise much of the liquid runs off, thus defeating the 

 desired end of a light deposit over all the leaves, and furthermore largely 

 increasing the risk of burning the leaves. This needs a very good 

 machine with a powerful pump, a fine dividing jet, and, last but not least, 

 excellent judgment as to when to leave off spraying on a tree. Spraying 

 is indeed a fine art, and this is one of its most difficult achievements. 



Either of these two remedies if applied at the right time, and given 

 favourable weather, will be found fatal to the various winter caterpillars 



* 2 lb. tobacco to 10 gallons of water ; impossible for growers to prepare, 

 f 1 lb. to 200 or 2-50 gallons of water. 



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