THE BEET-SUGAR INDUSTRY IN THE UNITED STATES. 47 



and Europe. One of these is known as Ceroospora and the other 

 as Phoma ; the latter is the same fungus that produces the root-rot. 

 When the spores of either of these fungi fall upon the beet leaves 

 and the conditions are favorable the fungus growth attacks the tissue 

 of the leaf, producing distinct and characteristic spots. The Cerco- 

 spora fungus does not generally attack any part of the beet plant 

 except the leaf blade and the petiole, while the Phoma may attack 

 leaf and root. If these fungi are present in large numbers they may 

 do considerable damage to the beet crop. If the attacks are severe 

 early in the season, the growth of the beets is retarded and conse- 

 quently the yield is reduced. If the attacks do not occur until late 

 in the season, after the beets have practically reached their normal 

 growth, the diseases will reduce the sugar without appreciably af- 

 fecting the tonnage. If these fungi attack the beets in midsummer, 

 both the yield and the quality will be generally reduced. These 

 diseases may best be controlled by deep fall plowing and by crop 

 rotation. Crop rotation is especially recommended where it can be 

 practiced, but in cases where it is necessary to follow beets with beets 

 after these diseases have appeared, the ground should be plowed in 

 the fall to a good depth, not less than 12 to 14 inches. In fact, all 

 plant-pathological problems, from a practical standpoint, are closely 

 connected with the cultural phases of crop production. Production 

 can not be successfully studied without a knowledge of the diseases 

 affecting that particular crop, nor can the disease of a crop be in- 

 telligently considered with reference to control measures except in 

 conjunction with the cultural practices and with a knowledge of the 

 conditions under which that crop is grown. 



INSECTS. 



The principal insects affecting sugar beets have been treated in 

 various publications of the Bureau of Entomology. A list of these 

 publications is given at the end of this bulletin. Among the im- 

 portant forms which affect the leaves are the webworms and the 

 beet army worm. In some localities blister beetles, flea beetles, and 

 local pests do considerable damage, mainly by destroying the foliage. 

 They also have a retarding effect on the growth of the beet, but the 

 principal injury is due to the destruction of the foliage and the con- 

 sequent expenditure of energy and food required by the plant to 

 produce a new set of leaves. Usually these insects start in small 

 areas on one side or a corner of a field and sjoread rapidly. Of some 

 species there are several generations in a season, and if weather con- 

 ditions favor their development much damage is frequently done. 

 In the case of insects working early in the season the tonnage of the 

 beets may be greatly reduced, and if the insects continue until late 



