Pests and Diseases 203 
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. 
Rhizoctonia. 
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 betae 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 aérated 
and in a good sanitary condition — help in retarding its 
growth. 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 
