losses from powdery mildew. So far no satisfactory control measure 
for virus dissases has been developed. 
Carrots 
The diseases responsible for most of the losses in carrots are 
bacterial leaf spot, which causes a leaf spot and dark spots on the 
roots, cercospora blight and alternaria blight, which danage the 
foliage, black rot of the roots, injury by the root-knot nematode, 
and yellowing and distortion of the leaves due to the aster yellows 
Virus. 
Bacterial leaf spot occurs chiefly in California and the other 
Southwestern States. The other carrot diseases are present wherever 
the crop is growmm. The fungus leaf spots, however, cause serious 
damage only where thers is a hunid climate during the growing season. 
Losses from leaf spot can be reduced by the use of fungicides, 
seed treatment, and crop rotation. Rotation is also the means 
generally employed to control the root-knot nematode. Losses from 
aster yellows can be reduced by dusting with insecticides to control 
the leafhnoppers that transmit the virus. 
Cauliflower 
The diseases causing most of the losses in cauliflower are the 
same as those that affect cabbage. They are of about the same im- 
portance on both crops, exeept yellows to which cauliflower. is re- 
sistant. Control measures are the same, 
Celery 
Celsry is subject to losses caused by leaf blights, Fusarium yel- 
lows, stalk rots, root-knot nematodes, virus infections, and non=- 
parasitic disorders. 
the major leaf diseases are early blight and late blight, and 
some loss is caused by bacterial leaf blight. The root-kmot nema- 
tode and the stubby root nematode are responsible for serious losses 
in Florida and root-knot injury occurs in other sections. lhe 
cucumber mosaic and the western aster yellows virus cause appreciable 
loss. the important nonparasitic diseases are blackheart, caused 
by sudden saturation of the soil with water, and cracked stem, which 
is due to boron deficiency in the soil. 
Most of the major diseases of celery occur wherever the crop is 
grown, although pink rot is most common in Florida. Western aster 
yeliows is limited to western States and is damaging chiefly in 
California. 
Losses from leaf blights can be reduced by the application of 
fungicides and by hot-water treatment of the seed. A variety re- 
mae 
