304 Gardening 
easily spread, much in the same way as the spores of the 
tomato-leaf blight are spread. The filaments of the 
fungus penetrate to the interior of the pod and infest 
the seeds, and here they may remain, ready to thrive 
on the young plant when the seed germinates. 
Control. Do not cultivate or hoe the crop, or pick 
the pods when the plants are wet from rain or dew, as 
this spreads the spores from plant to plant. Burn all 
badly infected plants and destroy the vines of others as 
soon as the crop of pods is harvested. This helps to 
check the spread of the disease to later crops. 
The chief means of prevention is through seed selec- 
tion. The fungus is carried over winter on the seed, and 
the very first leaves (the seed leaves or cotyledons) may 
already have the fungus present inthe seed. Do not save 
seed from infected pods. This is one of the seed-borne 
diseases whose presence can often be detected with the 
unaided eye. Examine carefully the seed that is bought 
for planting, and reject all seeds that show dark or red- 
dish spots indicating the cankers of the fungus. Seed 
treatment with fungicides has not thus far proved success- 
ful in controlling this fungus. The filaments penetrate 
deeply into the embryo itself, and a treatment which 
destroys the fungus also usually kills the embryo. 
PREVENTING PLANT DISEASES 
From the above discussion of the diseases typical of 
plants grown in the vegetable garden, it will be evident 
to the reader that thefe is no one means of control suitable 
for all diseases. The best method to use is largely deter- 
mined by the way the particular fungus lives and how it 
