124 FUNGOUS DISEASES. 



spread by cabbage-eating insects which pass from 

 the diseased to the healthy leaves. The manner of 

 infection is shown in Fig. 27. The disease has 

 invaded to areas which are left white in the illustra- 

 tion (B B), with the veins blackened (C C). In one 

 case the germs entered through the water pores (D), 

 in the other along the margins of the hole eaten by 

 insects (A). 



If rotting cabbage plants are left in the field, 

 the germs pass the winter in the soil and reinfect 

 cabbages, turnips or weed plants which may grow 

 thereon the next season. 



If fed to stock they pass into the manure and 

 are similarly propagated in that way. 



Remedial Measures. — Consideration of the 

 above facts shows the need of the following pre- 

 ventive or remedial measures where the disease is 

 observed : 



Cabbages or turnips should not be planted a 

 second year upon land where the disease is observed. 

 In view of the dangers from this disease and club 

 root, it is better in any case to rotate these crops 

 with others. The seed bed also should be made in 

 new soil each year. 



Diseased cabbages should, never be fed to ani- 

 mals tmcooked. Manure from animals fed on gar- 

 den refuse should not be used on soil intended for 

 cabbages. 



Keep the plants as free as possible from insects. 



Where the disease has once appeared, the cab- 

 bage field should be watched, and during August 

 and September should be systematically gone over 

 and all leaves removed and destroyed as soon as they 



