282 THE FORAGE AND FIBER CROPS IN AMERICA 



fall plowed, care being taken to spread the beet tops uniformly; 

 otherwise an uneven oat crop will result, since the tops are a 

 valuable manure. On account of danger of leaf-spot, at least 

 four years should elapse between two crops of beets on the same 

 soil. 



351. FUNGOUS DISEASES. Beets are more or less affected by a number of 

 fungous diseases, the most important of which in America are (1) leaf-sp:>t 

 (Cercospora beticola Sacc.), (2) root-rot (Rhizoctonia betae Kuhn.), and (3) 

 beet scab (Oospora scabies Thaxter). Of these the leaf-spot is the most 

 widely distributed, and probably for that reason does the most damage. This 

 is a mycelium fungus whose fruiting spores occur in small brown spots, 

 turning ash-gray with reddish-purple margins on the surface of the leaves. 

 Spraying early with Bordeaux mixture is recommended, but a rotation of crops 

 is a successful prevention. Late planting reduces the attacks from leaf-spot, 

 but late planting also reduces the yield, and is therefore not to be recommended. 1 



Beet root-rot affects the root while growing in the field, causing the infested 

 part to turn brown. Under conditions favorable to the disease all parts 

 become affected and gradually disappear. This fungus is also believed to be 

 the cause of damping off in young plants of several species, such as cotton 

 and lettuce. It is said not to thrive in an alkaline soil, hence liming 

 is recommended. 



Beet sc^b causes the surface of the beet to become more or less covered 

 with a corky excrescence. This disease is the same as that occurring on 

 potatoes, hence beets should never follow on land that had grown scabby 

 potatoes, or scabby beets. 



352. INSECTS. The beet being closely related to some of the commonest 

 weeds, there are about 150 species of insects which feed upon it; although 

 only about 40 species can be considered of economic importance. Ordinarily 

 none of these is especially harmful, beets being usually less injured by insect 

 attacks than maize, wheat, cabbage, turnip, or potato. "The principal in- 

 jurious groups are the leaf -miners, the web-worms, the cutworms, the woolly 

 bears, and several other leaf-eating caterpillars, the wireworms, the white 

 grubs, the flea-beetles, the blister-beetles, the plant bugs, the leaf-hoppers, the 

 plant-lice, and grasshoppers." 2 Spraying with suitable insecticides, and, in 

 other cases, hand-picking are practised, but the usual preventive measures of 

 clean culture and a rotation of crops are the most effective and practical. 



353. Preparation of the Soil. In the preparation of the soil 

 greater care is necessary than for cereals. Usually deep fall plow- 

 ing is advisable with cross-plowing or deep disk harrowing in the 



*New York Cornell Sta. Bui. No. 163 (1899). 

 2 Illinois Sta. Bui. No. 60 (1900), p. 398. 



