294 MISSOURI STATE HORTICULTURAL SOCIETY. 



one hundred species of insects attack different parts of this one plants 

 AVlien we come to consider the diseases caused by fungi, it is some- 

 what ditticult to estimate the amount of damage caused by the ravages 

 of these pests. It is also difficult to estimate the numbsr of speciea 

 which cause the various diseases of the apple. Of course we do not 

 pretend to say that all the diseases to which an apple tree is subject 

 are caused by fungi. It would be just as sensible to say that all the 

 diseases to which man is subject are caused by the members of a cer- 

 tain class of parasites. 



When we speak of a plant being diseased, we mean that the vital 

 functions of that ])lant are not acting in a normal way. In fact, a 

 disease is a derangement of the vital functions, and this derangement 

 may be caused by an over amount of stimulating food which the plant 

 receives. Or, if the plant cannot obtain a sufficient quantity of food^ 

 disease will follow. Excessive cold or heat will in the end produce 

 that derangement of the vital functions which we call disease. 



The study of the minute parasite we call fungi, in their relation to 

 the diseases of plants, is attracting considerable attention. There can 

 be no doubt that the yearly loss to our crops occasioned by fungi is 

 something enormous. Take for example, the fungus {Phj/topJithord- 

 infcstans,) which causes the rot in potatoes. Frequently the ravages 

 of this pest destroys forty i)er cent, of the entire potato crop. 



Michigan annually produces about 000,000 bushels of potatoes- 

 Last year about one-third of the crop was destroyed by the fungus 

 Fhytophothora infestans. 



Several botanists in different parts of the country are devoting all 

 of their time to the study of the fungi. Col. Colman, our present com- 

 missioner of Agriculture, has lately api)ointed a botanist to a position 

 where he can devote all of his* time to the study of plant diseases- 

 Thus the work goes on; new species are described almost daily, and 

 we are constantly learning more of the habits of the old species. Dur- 

 ing the present year I have collected fourteen new species within the 

 borders of our own State; several of which are quite destructive. 



It must be borne in mind that fungi are true plants. They never 

 originate spontaneously, but each species owes its existence to a parent. 

 They live, grow, produce bodies analogous to the seed of higher plants 

 and finally die. Many species of fungi live upon dead or decaying 

 matter.* Such species are known as Saprophytes. Parasitic fungi are 

 those which obtain their food from the living })lants, living and growing 

 at tlie expense of the vitality of the host or supporting plant, frequently- 

 destroying the very plants which furnish us with food. 



