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VEGETABLE FOES AND DISEASES 



mycelium in part becomes latent until the following 

 season, when it may renew its activity and grow up 

 along with the stems springing from the tuber, giving 

 rise to the disease known as " curl," and the spores of 

 the fungus being produced the disease rapidly spreads 

 over a whole field, parish, county, or country. 



The sexual mode of reproduction is not developed 

 in Phytophthora infestans, hence there are no resting 

 spores or oosphores, and consequently the only means 

 of re-infection is from reproductive bodies originated 

 from latent mycelium. 



Prevention. i. Burn all the tops after the crop 

 is gathered, as the mycelium may hibernate in them, 

 especially in axillary tubers not unfrequently pro- 

 duced on the stems. 2. Gather all small and diseased 

 Potatoes, as the mycelium hibernates in them, and, sur- 

 viving the winter in the ground, may start the disease 

 anew. 3. Select seed for planting from localities 

 exempt from disease in previous season, always exer- 

 cising great care in selecting seed, preferably from a 

 different soil, never using other than sound sets, for 

 diseased tubers are the principal means of infection. 

 4. Rotate the crop, for the means of infection cer- 

 tainly survive in the Potatoes and stems left in the 

 ground. 5. Thoroughly work the land, having it in 

 good tilth and perfectly clean. 6. Plant early in the 

 season, early or second early varieties in March, and 

 all in April, the earlier the better as befits variety and 

 location, for the plants acquire a better disease-resisting 

 habit. If manure be used at time of planting let it be 



