Plant Diseases and Insects-. 



in different parts of the country. Entomological bulletins, 

 from Oregon indicate 4 'that the asenical mixtures must be 

 used in greater dilution than in the east. This point had 

 already been brought out by California experiments. The 

 Oregon people have found that one pound of London purple 

 to 150 gallons of water will burn the foliage of the apple."* 

 Benjamin Hammond informs the writer that trees near the 

 sea-coast are more liable to injury from the arsenites than, 

 those growing in the interior states. But the variation in 

 strength of Paris green and London purple may be so greats 

 and the methods of application so various, that we cannot yet 

 generalize upon this subject. 



The time and frequency of spraying for the curculio are 

 still moot points, although it is well established that several 

 applications are necessary. There are several circumstances, 

 which complicate the matter. Spraying trees while they are, 

 in bloom, although it may destroy some curculios, appears to 

 be fatal to bees, and there is a possibility that it may interfere 

 with pollination. On the other hand, there is some indica- 

 tion that in mid-season the spray is more harmful to foliage 

 than it is earlier in the season. But if the poison is suffi- 

 ciently diluted no harm can result to foliage. Spraying three 

 or four times at intervals of a week or ten days, or oftener if 

 heavy rains occur, appears to be the proper practice. 



4. Desirability of Laws to Control Insect Ravages and 



Plant Diseases., 



There is an increasing demand for legislation, designed to 

 check the spread of injurious insects and plant diseases. In 

 America the chief activity in this direction within the past 

 year has been the discussion of measures for the eradication 

 of yellows in the peach. It is evident that all, the states in 

 which yellows prevail to a serious extent will soon have radical 

 laws for its control. The Michigan law, probably the first one 

 framed in this country for the purpose oj mitigating a partic- 

 ular and specific disease of plants, serves as a model for dis- 

 cussion and enactment. California has a general law directed 

 against " any insect or insects, or the germs thereof " which 

 are injurious to fruit, or ''any Qontagipus disease known to bje ; 



*Insect Life, ii. 56. 



