160 INJURIOUS INSECTS OF I9Q09Q AND IQIO. 
fall out, leaving many holes in the leaves. This occurs also on 
sugar beets. 
Spraying with 5-5-50 bordeaux, first when the plants are six 
weeks old and then at ten-day intervals, gave a large increase in 
yield over unsprayed plots in the east. 
ScaB: See Potato Scab. 
Cabbage and Cauliflower. 
The principal enemy is the so-called cabbage worm, the larvae 
of the common white cabbage butterfly. The ordinary arsenical 
insecticides readily keep these in check. 
Biack Ror: This is caused by bacteria. The first symptons 
of the disease appear as a yellowing of the edges of the leaves. 
Later the leaf veins become black, and the outer leaves may fall off, 
in bad cases leaving the stem with only a few leaves near the top. 
Moist conditions are especially favorable to the spread of the dis- 
ease, since the bacteria enter through the water pores at the edge 
of the leaf. All heads which show signs of infection should be 
rejected, since a soft rot which may spread to the other heads is 
likely to ensue. Such heads should not be fed to stock, the manure 
of which is to be used on land used for raising cabbage. Clean 
cultivation and rotation should be practiced, since the disease may 
live over in the soil. It may also be carried over in the seed, so 
only clean seed should be made. As an extra precaution, seed 
should be soaked 15 or 20 minutes in formalin, 1 pound to 30 
gallons. The same disease occurs also on many other plants of the 
mustard family, both wild and cultivated, such as shepherd’s purse, 
common wild mustard, kohl rabi, brussels sprouts, kale, rape, tur- 
nips, etc. This should be taken into account in attempting to con- 
trol the pest. 
Crus Root: Club root is caused by a slime mold, an animal 
fungus. It causes, on plants of the mustard family, large swellings 
or galls on the roots which later decay. The above ground parts are 
affected by the general decrease in vigor so that, in many cases, they 
fail to head. 
All refuse and diseased parts should be destroyed, and care 
should be taken not to use manure which may have come in contact 
with diseased parts. Since the soil, when ence infected, may remain 
so for several years, a rotation should be practiced. An applica- 
tion of air-slaked stone lime, at the rate of about 75 to 80 bushels 
