16 



COMPULSOBY TREATMENT OF INFESTED OBCHABDS. 



The general enforcement of horticultural laws of this class is attended 

 with difficulty. The actual inspection of every orchard in the State 

 demands an amount of work that the service provided does not succeed 

 in accomplishing. While undoubtedly the most direct means of con- 

 trolling pests, its efficiency would probably be increased by limiting 

 the number of insects or diseases whose control is attempted. The 

 sentiment seems to be growing among orchardists in the Northwest 

 that every means, including compulsory treatment, should be enforced 

 to control insects or diseases that injure or destroy orchard trees; that 

 this is more important than to expend the necessarily limited energy 

 of the officials in combating pests that affect merely or mainly the fruit. 

 It is objected b}^ some that it is practicall}^ impossible to compel an 

 unwilling person to carry out any compulsory treatment properly, and 

 by others that, even if compulsory treatment for such pests as codling 

 moth and apple scab is enforced, it will not to an appreciable degree 

 make it cheaper for orchardists in general to raise first-class fruit. In 

 short, it is argued that the law can not be fully enforced, and that 

 it makes very little difference if it is. But these difficulties remain 

 whether we consider only tree-injuring or only fruit-injuring pests. 

 After all, the exercise of wise discretion on the part of the officers of 

 the law would seem to be necessary. In any case it would seem wise 

 to endeavor to prevent the spread of a new disease or insect as much 

 as possible. So far as well-established enemies are concerned, it would 

 appear to be wisest to enforce the law only where there is a reasonable 

 hope of exterminating them or confining their spread. 



INSECTICIDES AND THEIR PREPARATION. 



Two general classes of insecticides are commonly used in spraying, 

 namel)^, those which kill by external contact and those which kill by 

 internal poisoning. The former are used almost exclusively against 

 such insects as plant lice and scale insects, which obtain their nourish- 

 ment from the plant by means of sucking beaks. The latter are useful 

 only against insects which obtain their food b}^ biting or gnawing. 



Attention to these fundamental differences will prevent the mistake 

 too frequently made of spraying with Paris green or similar poisons 

 for such insects as plant lice or the San Jose scale. 



Of contact or external insecticides the most important to the Pacific 

 Northwest are the sulphur-salt-lime wash, kerosene emulsion, and 

 whale-oil soap with or without quassia. 



Of internal poisons the arsenicals only are used, Paris green being 

 the most common. Paris green is sometimes adulterated, and this, 

 in part at least, accounts for some complaints of nonsuccess attend- 

 ing its use. To be sure that the article purchased is reliable, it is 



