POTATOES. 349 



designated the potato-bug. Other difficulties are occasionally met by the farmer in raising 

 this crop, such as the scab, and attacks from the grub, but these are slight when compared 

 with the effects of the former. 



Potato Hot. In 1845 the potato rot was very destructive to the crops in the United 

 States and a large portion of Europe. In Ireland especially, where the potato constitutes 

 the principal article of food, great distress was experienced at this time. This disease was 

 so violent in its attacks, in many sections, that whole fields often turned black and rotten in 

 the course of a few hours. In other localities its progress was more gradual, but none the 

 less effective. This disease has made its appearance several times since 1845, but never with 

 as much severity and the occasion of such extensive loss as at that period ; in fact, it is liable 

 to occur to a limited extent in almost any damp season, being caused by a parasitic fungus 

 which attacks the plant, and to which a damp and rather warm season, or such a condition of 

 the atmosphere as is commonly termed &quot;muggy,&quot; is best adapted. 



This disease is still but imperfectly understood, and there is no effectual remedy known 

 when it once makes its appearance. The stems and leaves of all diseased plants should 

 always be destroyed, to prevent its spreading. By the use of lime in the hills and dusting 

 the growing plants occasionally with it. as well as a similar use of either salt, charcoal dust 

 or gypsum, crops have been known to escape its attacks in localities where other fields were 

 destroyed by it. Avoiding the use of fresh stable manure is also advised as a preventive. 

 It has long been known that a fresh sod that has remained untilled for several years is also 

 less liable to its attacks, and that early-planted fields are not as apt to be infected as those 

 later planted. When a field is slightly attacked, sometimes the preventive measure of mow 

 ing off the tops of the plants will prove effectual in checking it. It has also been found that 

 those crops cultivated by the use of commercial fertilizers are less liable to this disease than 

 where farm manures and composts of various kinds are applied to enrich the soil. 



Potato Bug, or Colorado Beetle. This insect has become the scourge of the 

 potato crop, and the greatest pest known to the farmer in the cultivation of this product, 

 which is one of such vast importance in the agriculture of our own and foreign countries. Its 

 destructive powers are so great, and its dissemination has been so extensive since 1860, that 

 few insects have attracted more attention during that period. In the year 1819 the noted 

 entomologist, Mr. Thomas Say of Philadelphia, accompanied the United States government 

 exploring expedition to the Northwest Territories, he being at that time the zoologist of the 

 expedition. While on this tour of exploration numerous species of beetles were found on the 

 upper Missouri near the base of the Rocky Mountains, among them the Doryphosa IQ-tineata, 

 which has since become commonly known as the Colorado Beetle, and which was first described 

 by him in 1824. It gradually extended its course eastward, and in 1859 we first learn of its 

 invading the potato fields in Nebraska. In 1861 it becomes known in Iowa, being assisted in 

 its course by railroads, doubtless, as they were often found in and on the cars of the trains 

 that had passed an infested district. They traveled eastward in a direct line over fifteen 

 hundred miles in sixteen years, and became spread over an area of about 1,500,000 square 

 miles during that time, until now its ravages are extended throughout the entire country, 

 and there seems to be no method known of wholly exterminating them, Paris green being 

 the most effectual remedy thus far tried for checking their increase. With this insect, as 

 with many others, it is the larva that is the most destructive to plants. 



Prof. C. V. Riley says of it: &quot; This insect hibernates in the perfect or beetle state under old 

 rubbish or in sheltered situations of whatever kind, but normally in the ground, generally but a 

 few inches beneath the surface, but exceptionally at a depth of three feet. A s vegetation starts in 

 the spring, it issues forth from the ground, and long before potatoes are up, or even planted, it 

 may be seen flying on genial days in search of food and company, the rose-red underwings 



