Pests and Diseases 20% 



in California. It has the appearance of the true rusts. 

 The leaves contain pustules of yellowish brown powder. 

 Cold damp weather favors the development of the dis- 

 ease, which may be controlled by a bordeaux mixture 

 spray, should it become sufficiently serious to justify this 

 measure. Affected leaves fed to stock may carry the 

 disease through the manure to plants the following season. 



Rhizocionia. 



The group of fungi called Rhizoctonia by De Candolle 

 seems to be responsible for injury to beets as well as to 

 potatoes. The beet Rhizoctonia has gone under the 

 name Rhizoctonia hetae Kuhn, and has been popularly 

 known as root-rot. This disease works principally in the 

 seedling stage of the plant. At this time, on account of 

 its girdling action, which is typical of Rhizoctonia, it 

 shuts off the movement of food to the roots and the plant 

 dies. 



No effective preventive measure for controlling this 

 disease is known. General sanitary conditions — drain- 

 ing the land and keeping the surface of the soil aerated 

 and in a good sanitary condition — help in retarding its 

 gro\vi;h. One precaution in handling the trouble is to 

 delay planting until the soil is warm enough to enable the 

 seed to germinate rapidly and for the seedling to get a 

 good start. 



Sugar-beet mosaic. 



This disease is increasing from year to year. In some 

 places it affects a high percentage of the plants. It causes 

 the leaves to turn a mottled yellow and to have a patched 



