Remedial Measures and Insecticides. xxxv 



In the case of the Japan quince, however, with the two stronger 

 mixtures, namely, those with one-third and one-fifth kerosene 

 emulsion, a few yellow spots appeared on the leaves, and later, 

 upon handling the limbs treated with the strongest mixture, about 

 one-fourth of the leaves were found to fall off readily. These 

 leaves, while looking comparatively healthy and green, had 

 evidently been injured more than their surface appearance indi- 

 cated. With No. 2 this peculiarity was almost unnoticeable, and 

 with Nos. 3 and 4 no injury whatever was shown, nor did any 

 further injury manifest itself throughout the season in the case of 

 any of the plants treated. These experiments would indicate that 

 the kerosene emulsion can be applied in much stronger dilution to 

 tender foliage of growing plants than has hitherto been supposed.' 



On the other hand, there are well-authenticated reports of 

 plants seriously injured, or even killed, by the use of too strong a 

 mixture, and the application during sunny weather is attended 

 with danger. In my own experience I have found the tender 

 shoots on a recently pruned tea bush to be completely killed back 

 by a comparatively weak mixture applied during sunny weather. 



When the foliage of a plant is attacked, the applications should 

 be made by means of a spraying machine. In the case of pruned 

 trees, when the pest affects the bark only, the liquid can be applied 

 with a brush or a piece of rag to the stems and branches. Care 

 must be taken that the liquid is not used in sufficient quantities 

 to run down and saturate the roots of the plant, or grave injury 

 may result. When employed with proper precautions, there is no 

 doubt that we have in kerosene emulsion a very valuable remedy 

 against scale and other insect pests. 



Milk may be substituted for the soap in the manufacture of 

 kerosene emulsion. The formula given by Hubbard is : — ' One part 

 milk (sour milk is said to be as suitable as fresh for the purpose), to 

 two parts kerosene. Heat the milk nearly to boiling point and 

 mix with the kerosene. Churn the mixture violently until a thick 

 creamy fluid is obtained. For use against scale insects dilute with 

 nine or ten times the quantity of water.' I have been unable to 

 find any definite statements as to the comparative effectiveness of 

 the milk and soap emulsions. It is possibly a question of cost. In 

 some countries a gallon of milk may be cheaper than half a pound 

 of soap ; but in most places it is probable that the balance of ad- 

 vantage will be on the other side. The active insecticidal properties 

 of soap itself must surely be an additional advantage. 



