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 in the 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 there 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 



