Insects Injurious to the Apple. 151 



PREVENTION AND TREATMENT. 



The employment of the Northern Spy and the Majetin varieties 

 for stocks, on account of their immunity, should be well considered 

 by growers and nurserymen as a means of preventing this pest. 



The treatment of this disease can only be satisfactorily done if 

 we attack it above and below ground at the same time. There are 

 many washes which will destroy it above ground, granted they are 

 properly employed. It is quite useless to treat trees affected with 

 Woolly Aphis with fine sprays. The trees must be not only well 

 wetted, but the wash must be sent with some force and applied to 

 the affected parts for some seconds. It is essential that first of all 

 the wool is removed ; unless this is done, I know of no substance, 

 except tobacco, that will penetrate to the insects and so kill them. 



A good hard washing with ordinary soft soap and quassia is 

 sufficient, but experience has shown that a small quantity of paraffin 

 is beneficial in summer, not more than 3 per cent, in the wash at this 

 time of year. 



In winter I have found Mr. Spencer Pickering's wash of paraffin, 

 soap and caustic soda most beneficial, and I do not think a better one 

 can be used at this time, although caustic alkali wash has been found 

 for the last six years to kill a very large quantity. 



No matter which is used, it is more the thorough application than 

 the actual wash that is of account. Unless the trees are heavily wetted 

 and the wash applied from all directions it will have but little effect. 



For winter washing for Woolly Aphis then, we may use either the 

 old caustic alkali wash or the more improved Woburn wash. 



For summer either soft soap and quassia, or a weak paraffin 

 emulsion. Force is necessary, and plenty of the wash in both cases. 



The ground form in old or established trees may be destroyed by 

 injections of bisulphide of carbon. Nothing else can be used as far 

 as we yet know in this country. 



The quantity for each tree, according to size, varies from 2 to 

 4 oz. This is best applied two feet away from the trunk, four 

 or more injections for each tree at equal intervals around the stem. 

 It is best injected by means of Vermorel's Injector, shown at work in 

 Fig. 126. The depth of injection should be about six inches. 



Care must be taken not to put the fluid on a large root. If the 

 point of the injector strikes a root, move to one side of it. The fumes 

 of the bisulphide are deadly to insect life in the soil, and penetrate 

 deeply into it ; they are quite innocuous to plant life, but the actual 

 contact of the liquid is harmful. 



