DAMAGE CAUSED BY PLANT DISEASES 13 



Aside from diminishing the value of the produce and 

 the thrift and future productiveness of perennials, as 

 trees, vines, etc., plant diseases entail depreciation in the 

 value of land, and in some cases even occasion large loss 

 of life. Thus the famous famine in Ireland in 1845 is 

 directly traceable to the injury done to the potato crop 

 by the potato blight. The presence of ergot in grain 

 used as food for cattle or man may result in disease and 

 death. 



The presence in land of the causal germ of the melon, 

 cowpea, cotton or tobacco wilts, of onion smut, cabbage 

 club root or black rot, or of any one of many other soil- 

 borne diseases precludes the possibility of successful culture 

 of the susceptible plant for a long period of years, perhaps 

 forever, upon the soil in question. Such restriction may 

 prevent the raising of just the crops that are most profitable 

 in that particular section, and in some instances depreciation 

 of 50 per cent or more in the market value of land has resulted 

 from the invasion of one of these ineradicable soil diseases. 

 Still more serious is this kind of injury if the crop in ques- 

 tion is one which requires large money outlay before the 

 presence of the disease germs is manifest. In the case of 

 Sumatra tobacco under shade, or lettuce grown under 

 canvas, the money expended to prepare for the crop may 

 aggregate from S700 to $1000 or even more per acre the 

 first year. The capture of such acreage by the lettuce 

 drop or the tobacco wilt is a far more serious matter than 

 a plant disease is usually considered to be. Some of the 

 money losses caused by diseases of a few crops are given 

 below, merely as illustrative instances. The authority is 

 named with each estimate. 



