The Canadian Horticulturist. 443 



to be covered does not exceed 8 or 10 acres, a force pump attached to a barrel, 

 and fitted with two discharge pipes with a Vermorel nozzle attached, will serve 

 the purpose very satisfactorily. Advertisements of pumps of this kind appear 

 in the Canadian Horticulturist. 



Green and wooly aphis are treated, not with poisonous substances, but 

 with oily mixtures which will kill by contact. The best of these is the kerosene 

 emulsion made according to the following formula : 



Kerosene (coal oil), - - - - 2 gallons. 



Rain water, -------- - - 1 gallon. 



Soap, -------- - half pound. 



Boil the soap in the water till all is dissolved ; then, while boiling hot, turn it 

 into the kerosene, and churn it constantly and forcibly with a syringe or force 

 pump for five minutes, when it will be of a smooth, creamy nature. If the 

 emulsion be perfect it will adhere to the surface of glass without oiliness. As it 

 cools it thickens into a jelly-like mass. This gives the stock emulsion, which 

 must be diluted with nine times its measure of warm water before using on 

 vegetation. The above quantity of three gallons will make 30 gallons of wash. 

 Insects breathe through small openings along their sides. The effect of kerosene 

 emulsion is to suffocate them, by stopping up these breathing pores. — Fletcher. 



Sun Scald or Bark Blister. 



593.— Sir,— I would like to ask your opinion in regard to a disastrous disease, known 

 here as a black spot or dead spot, that" is fast destroying our fruit trees, principally apple. 

 It makes its appearance on the bark of the tree, both on the stock and limbs of the young 

 trees, and on the smooth bark of the limbs of the other trees. I think you have made an 

 investigation before, but had not found out any cause or remedy. 



N. Butcherat, Port Moody, B. C. 



Reply by Prof. J. Craig, Central Experimental Farm, Ottawa. 



Sun scald, or bark blister, or canker, as it is variously called, is a malady 

 which seems to be somewhat peculiar to the region of British Columbia. Its 

 cause has not been satisfactorily determined, although it is supposed to be a 

 disease which owes its origin to some member of the lower order of plants 

 included in the general group fungi. 



Sun scald in the colder region of the Dominion seems to be directly 

 attributable to climatic changes, and to be more characteristic to some varieties 

 than others. 



Shading the trunks of the trees from the rays of the sun during winter and 

 spring, has been very successfully tried. 



It might be worth while to try this remedy on a small scale, although 

 indications of its beneficial effects are not encouraging. 



