142 — How to Make the Garden Pay. 



of preventing not only mildew but also the " soft rot',' which so 

 frequently attacks the hearts of forced lettuces when freely wat- 

 ered from overhead, than the new scheme of applying water by 

 subirrigation, as explained in Chapter XVII. 



Diseases of the Onion. — For the ''onion inildeui,'' -which 

 appears upon the tops as a grayish mold, followed by more or 

 less wilting of the affected leaves and the premature collapse of 

 the plant, strict rotation, the destruction by fire of all refuse tops, 

 and spraying with fungicides, where practicable, are recom- 

 mended as precautionary measures. Hot and dry weather favors 

 the development of the disease. By starting plants under glass 

 in winter and transplanting them to the open ground early in 

 spring, we can usually get the crop pretty much out of the way 

 before the period of danger. 



The ^' onion .rwzw/," which has become quite destructive in 

 some onion-growing sections of the East, lives in the soil, and 

 from there is transmitted to young seedling plants. It is easily 

 recognized by the appearance of the black, sooty powder (the 

 spores of the fungus). Badly affected plants always die, either 

 by drying up or rotting. Planting on new and as yet uninfected 

 land is the surest method of avoiding injury by onion smut. 

 The new onion culture also offers a way of escape. Healthy 

 seedlings grown in soil free from smut are not liable to take the 

 disease after being planted in open ground. It may be possible 

 to kill the smut in infected soil by watering with weak solutions 

 of copperas, permanganate of potash, or other fungicides, or to 

 protect the seedlings from infection by mixing flour of sulphur 

 and air-slaked lime in equal parts, and sowing with the seed. 



The *' onion spot" disease causes black specks and spots on 

 white varieties of onions after they are housed, especially in a 

 warm and moist room. Onions showing signs of this disease 

 should at once be sprinkled with air-slaked lime, thoroughly 

 cured, and when perfectly dry, stored in dry bins in a cool and 

 dry store-room. 



Diseases of the Potato. — The most malignant of all dis- 

 eases affecting the potato, is the '' dozvny mildew" also called 

 "late blight." Fortunately it is not prevalent to any great ex- 

 tent, except in. an occasional season when the atmospheric con- 

 ditions seem to be especially favorable to its development. 

 Usually it makes its appearance rather late in the season, conse- 

 quently early varieties always escape. But its attacks are fre- 

 quently sudden and fatal, the affected plants being killed right 

 down to the ground within a few days. The affected tubers rot- 

 producing the characteristic rank, rotten-potato smell. The dis- 

 ease is easily recognized by the mildew-like growth on the lower 



