CULTURAL DIRECTIONS 
28; 
time many of the infected plants will mature, although 
the heads are usually small. Plants set in the field 
in June or July seldom mature marketable heads if 
attacked by club root. 
The spores of this disease are inclosed by protective 
coverings that give them great vitality. It is not un- 
common for the disease to recur in soils where crucifers 
have not been grown for 10 or 15 years. With annual 
tillage the spores soon become mixed with the soil and 
the malady may spread over the field or the entire farm 
or the community, and as no treatment of the plants has 
been found effective, the grower must resort to preven- 
tive measures. The following paragraphs relate to ways 
of infestation or dissemination and methods of prevention : 
1. As young seedlings are most susceptible to attack, 
great care should be exercised in selecting soil for the 
seed bed. Affected plants should always be discarded. 
2. Rotation should be practiced, in which cruciferous 
plants should not be planted more frequently than every 
four years. 
3. The disease thrives best in acid soils. In Belgium 
the calcareous soils were the last to become infested, and 
lime is the best-known means of soil treatment, although 
often unsatisfactory. The New Jersey Station reports 
that 75 bushels of stone lime an acre gave as good re- 
sults as larger applications. The lime should be applied 
in the fall or at least several months in advance of 
planting. 
4. Roots, stems and leaves from diseased fields should 
be burned. If fed to stock or used for composting such 
refuse will be a certain means of disseminating the 
malady. 
5. In the purchase of all kinds of stable manures, the 
grower should make certain that the stock has not been 
fed plants which might cause infestation. 
