18 Colorado Experiment Station 
(3) A proper and uniform supply of moisture in the soil is 
beneficial. 
(4) If cattle or sheep are used in pasturing the tops, care 
should be taken that no diseased leaves are scattered to fields in¬ 
tended for beets the following year. Do not allow livestock to 
enter fields to be used for beets the following year until several 
days after they have been taken off from' the beet-top pasture. The 
spores of the leaf spot fungus pass through the alimentary canal 
of cattle uninjured. 
(5) Beet tops should be plowed under in the fall, to a depth 
of ten inches or more. 
(6) Manure from stock fed with diseased beet tops should be 
applied to the land one or two years in advance O'f the beet crop. 
Root Knot. —This trouble is caused by minute worm-like ani¬ 
mals (nematodes) which are invisible to the naked eye. It is often 
mistaken for a fungus trouble. No deformities are produced on the 
beet above ground. Badly infested plants are dwarfed, wilt eas¬ 
ily, and are usually a pale green. In severe cases, the plant may 
be killed. Galls may form on fine feeding roots, or on larger roots. 
These enlargements are scattered, or close together and produce 
abnormal thickening of the root system. In severe cases the roots 
are a swollen mass. 
Control .— (i) Rotation of crops. Cultivate immune crops for 
two or three years. Kill all weeds and other plants in which the 
worm-like animals live. Plants not attacked are barley, corn, broom 
corn, millet, red top, rye. sorghum, timothy, wheat, and winter oats. 
(2) Prevent running water, implements, animals, etc., from 
bringing the nematodes from near-by infested fields. 
(3) Starving the parasite by keeping the land free from all 
vegetation for two years is an effective control method, though often 
impracticable. 
Crown Gall. —The crown gall of beet is caused by the same 
organism which produces galls of the apple. The characteristic 
swellings or galls may be produced upon any portion of the beet 
root. See crown gall on apple. 
Control .—Rotation is the only effective remedy if the bacteria 
once gets into the soil. Plants which are not attacked, like the 
grains or grasses, should be used in the rotation. 
BLACKBERRY. 
Leae Spot. —Diseased spots are small and numerous. They 
have a white or ashy-grav center, bordered with a brown or reddish 
ring. In later stages, minute black specks may cover the center of 
