SAVE US FROM INVADING PESTS 



149 



material, 508 distinct species of insects, and 189 distinct 

 plant diseases have been intercepted on plant imports 

 from abroad. It is safe to presume that a considerable 

 number of these would have developed to the stage of 

 serious and destructive pests, if we may judge from pcr- 

 fonnances of similar introductions in the past. Bj^ no 

 means, however, has our inspection been able to prevent 

 the introduction and establishment of numerous insects 



Among the many plant diseases which have probably 

 been introduced, and are now demanding serious con- 

 sideration are the asparagus rust, alfalfa leaf spot, bean 



abb c c c 



BARLEY INFECTED WITH DISEASE 



(a) A sound head of barley. 



(6) Two heads affected with covered smut, an easily prevented disease which 



causes an estimated annual loss of $2,100,000. 



{.€) Three heads affected with loose smut, a disease preventable by hot water 



treatment. Causes annual loss of $1,225,000 to the farmers of this country. 



and diseases, some of which may even now be established 

 and are rapidly multiplying, but as yet have not attracted 

 the attention of the scientists. 



A list of the introduced insect pests and plant diseases, 

 which have become established in this country, would be 

 too extensive and lengthy for consideration at this time, 

 but I will enumerate a number of the more important ones, 

 and I am sure that you will recognize a large number of 

 those pests which we consider of prime importance in 

 America. 



It is my rather hasty detei-mination that approxi- 

 mately 75 per cent of the major insect pests and plant 

 diseases of the United States have been introduced from 

 abroad. Surely some of the most destructive ones are in 

 this category. 



POTATO POWDERY SCAB 



A disease probably originating in South America, carried from there to Europe, 

 and thence to Canada and the United States — at one time the cause of serious 

 alarm and a temporary quarantine. It has fortunately turned out to be a 

 disease of cool, moist climates, and unable to spread in most parts of this country. 



anthracnosc and rust, European apple canker, a]jple 

 scab, pear scab, brown rot of various fruits, the downy 

 mildew of cruciferous plants, the chrysanthemimi rust, 

 chestnut blight, diseases of cotton, carnation rust, the 

 hvacinth disease, the hollyhock rust, the loose smut of 

 oats, the olive knot disease, the peach leaf curl and 

 peach scab, ergot affecting rye and allied cereals, violet 

 rust, loose smut and rust of \\'heat and other grains. 

 Also, those recently intro- 

 duced diseases, the wliite pine 

 lilister canker, the citrus canker 

 and the poplar disease. 



In this list those of you 

 familiar with plant diseases 

 have noted a large number 

 of our serious plant pests; 

 those more familiar with the 

 insect pests will recognize, in 

 the few which I have listed, 

 some of the most serious 

 creatures ever introduced into 

 this country — the San Jose 

 scale, the fluted scale of cit- 

 rus, the oyster -shell scale, 

 black scale, red scale of Cali- 

 fornia, red scale of Florida, 

 European fruit scale, Euro- 

 pean fruit lecanium, cottony 

 maple scale and the tulip tree 

 scale, as well as many other 

 scale insects which are pests apple scab 



in greenhouses throughout the This scab affects the leaves as well 

 ° as the fruit and reduces greatly the 



country, the codling moth, food-making surface of the tree. 



