108 FAEMERS' INSTITUTES. 



the way by the time the rot appears, the vines and tubers are so mature that for 

 some reason they seem almost exempt from attack, even when rapidly growing 

 late sorts near are badly affected. The plan of avoiding the rot by having the- 

 crop early was long ago adopted by the farmers of England and Ireland, who 

 in order to obtain an early start place their seed potatoes in a warm place in 

 the house or barn for a few weeks before planting, to have them well sprouted. 

 Every means possible should be used for this purpose, — a warm exposure, sandy 

 soil, frequent cultivation, liberal fertilization (except with raw manures) — every- 

 thing tluit will bring forward the crop as rapidly as possible. In some experi- 

 ments on the Mercer potato, published in the report of the New York Agricul- 

 tural Society for 1860, Geo. K. Underbill states that of three plantings at inter- 

 vals of three weeks, and under otherwise similar conditions, the first planted 

 about April 1, ripened without the appearance of the disease ; the second plant- 

 ing rotted to a small extent, and the third rotted badly. 



3. Another remedy largely used, is hilling up. Of late years this practice is- 

 being discontinued in this country, and except to a slight extent in some cases, 

 to protect the tubers from becoming sunburnt, it doubtless is generally of more 

 injury than benefit. But there is a large amount of evidence to show that 

 potatoes hilled up, so that the hills will shed rain, are less liable to the rot. 

 Mr. Erwin F. Smith, in an excellent article on the potato rot in the Michigan crop 

 report for December last, states that hilling potatoes is not a remedy. The 

 reason given is based largely on the experiment of DeBarry, already described, 

 in which spores of the fungus placed on the surface of the ground and water 

 applied caused rot in tubers buried beneath. The spores are so minute that 

 they are easily carried into the soil with the water, where they germinate and 

 attack the potatoes. It is obvious that hilling up, to be of use, must exclude 

 the water at the time the spores are ripe. In addition to hilling up some grow- 

 ers in France and England have thought that they have lessened the liability 

 to rot by pressing the top to one side over the furrows by means of a light 

 roller, so that the spores which fall will be washed into the soil beyond the 

 reach of the tubers. Great care is also taken in hilling up to press the earth 

 close about the stems in the middle of the hill so that water will not enter at 

 that point. So far as I can judge hilling up seems to be a partial remedy and 

 deep planting to have somewhat the same effect. 



4. Another remedy, in case the blight appears on the tops, and when from 

 the state of the weather a severe attack may be expected, is to mow or pull the 

 tops. If frost occurs this is not necessary. The tubers of course will not 

 enlarge after the tops are removed. 



5. As to whether it is best to dig at once on the attack of rot, or leave the 

 crop in the ground as long as possible there is difference of opinion. The safest 

 way is probably to dig at once, certainly if the ground is wet. 



6. In storing it is important to have a cool, dry place and dark. The partly 

 decayed tubers should be separated as much as possible from the others, for 

 although it is not certain that the disease spreads from affected to sound pota- 

 toes, the presence of the moisture from those badly decayed seems to cause the 

 rot to spread more rapidly in those less decayed. The presence of fermenting 

 tubers probably raises the temperature somewhat, and so also aids the spread of 

 the disease. Air-slaked lime is sometimes used' to check the rot. So far as 

 this tends to dry the tubers it is of use. It is also said that the fruiting 

 branches of the fungus are sometimes found on the tubers. They certainly 

 have on those which were cut. lu such a case lime would doubtless destroy the 

 spores and prevent them attacking sound tubers. 



