542 NEW JERSEY AGEICULTURAL COLLEGE 



duced into this country from South America, the wet years have 

 been the seasons of most rot. A moist atmosphere favors the develop- 

 ment of the fungus in the leaves and stems; the rains assist in con- 

 veying the germs (spores) from the foliage to the tubers, and the 

 wet soil encourages the growth of the filaments that may have reached 

 the potatoes by descending through the stems. A second favoring 

 condition is warm weather — not hot or cold, but a condition of the 

 atmosphere which ol)tains when there is a week or month of showery, 

 summer weather, often spoken of as ''close" or "muggy" — just such 

 weather, in fact, as we have experienced throughout the State during 

 August. A large quantity of decaying organic matter, as coarse 

 barnyard manure, perhaps, stimulates the development of the rot, 

 especially if accompanied by favorable conditions of temperature and 

 miosture. 



Treatment of Infested Fields. — It is evident that, after the vines 

 have been killed, there can be no further growth of the tubers, and 

 as the disease first attacks the leaves and tips of the vines and works 

 downward towards, and finally into, the tubers, it follows that there 

 can be no loss in yield, and a great possible gain in healthfulness, by 

 early digging. As a rule, the potatoes should te removed from the 

 soil as soon as possil)le after the vines have been "struck" by the rot. 

 The dead vines abound in the spores of the disease, and it is possible 

 for the tuk'rs to be infested ])y contact with the vines at the time 

 of digging. Therefore, it is an important and inexpensive precau- 

 tion to rake the vines into heaps and Irarn them before the potatoes 

 are dug, at the same time destroying millions of germs of the rot, 

 some of which might otherwise do injury elsewhere. 



Treatment of Harvested Tubers. — The same conditions favor the 

 rot after as before digging, and, therefore, the dug tulwrs should 1)6 

 left to dry thoroughly, then the sound ones can be stored where they 

 can be kept dry, cool and with a good circulation of fresh air. A 

 damp, warm, close cellar favors the growth of the rot. Air-slaked 

 lime, a handful or so per bushel, may be dusted over the freshly- 

 harvested potatoes to destroy any adhering germs. 



Preventive Measures. — The conditions which favor the rot are not 

 under human control, but knowing the habits of the pest and that it 

 does not usually make its appearance until midsummer, it follows 

 that early varieties of potatoes, when planted early, will usually ma- 

 ture before the rot appears, and thus escape. It is also to be borne 

 in mind that a loose, light soil does not promote the decay like a 



