VEGETABLE AND FIELD CROPS ^'-- ^" 



These crops cover a wide range in cost of production ; some 

 being grown in glass houses with artificial heat, others under 

 canvas in cold frames, still others under ordinary field condi- 

 tions. With crops of high value, corresponding!}' expensive 

 methods of disease control are warranted, while with the 

 field crops, resort must be to spraying or to less expensive, 

 general methods of sanitation and field practice. 



The crops following are arranged alphabetically by their 

 common names, except that several crops of a botanical 

 famil}^ when generally affected by the same diseases, for 

 convenience of discussion, are grouped together. 



ASPARAGUS 



Rust i"^"!"'' (Pucdnia asparagi DC). — Asparagus rust, 

 though observed in Europe as early as 1805, was not noted 

 in epidemic form in the United States until 1896, when it 

 was recorded by Halsted as occurring in several New Eng- 

 land States. In 1897, though it had passed to South Carolina 

 and to some extent westward, the interior and western part 

 of the United States seemed still free from it. In 1898 it was 

 first found in Michigan; in 1899 in Illinois, Ohio, and Kansas; 

 in 1900 in Dakota, Nebraska, and Texas, completing its 

 westward march into California in 1900 or 1901. Now it is 

 found in every state where asparagus is grown. 



Rust usually first attracts attention by its effect upon the 

 green tops which redden under the disease, this symptom 

 appearing at any time after lilossoming or coming to leaf. 

 Diseased areas in the field enlai'ge rapidly, and soon the 

 affected leaves yellow and fall, leaving the bare, dead stalks. 

 Close examination in the field shows that the twigs and 

 leaves bear many small skin blisters (sori) under which is a 

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