Plant Diseases and Insects. 77 



sit}' of thorough weeding, 3'et, with all the care given, many 

 farms are almost ruined b}^ noxious weeds. Is it any wonder, 

 then, when it is considered that the study of plant diseases is 

 only a few years old and that few attempts have been made 

 to combat injurious fungi, that orchards, gardens, and green- 

 houses are filled with these tiny parasitic weeds, visible only 

 by the aid of the microscope ? These minute fungi which 

 grow upon the living parts of our cultivated plants and send 

 their roots, or vegetating threads, deep into the leaf or stem, 

 instead of into the moist earth, have probably been here as 

 long as the oaks or poplars, and the fungus causing the grape 

 vine mildew has just as much right to be considered an old 

 inhabitant of the globe as the vine upon which it lives. The 

 maladies of plants, like the plants themselves, are migratory, 

 and we must expect to find new diseases in our greenhouses 

 and orchards just as much as new weeds in the garden. 

 While it may be said that this tendenc}^ to spread or migrate 

 may explain in part the apparently sudden appearance of 

 these diseases, the main reason is that we do not notice them 

 when they first begin their work. The average farmer or fruit 

 grower passes, unnoticed, hundreds of fungous diseases of 

 his growing crops ascribing causes of 'the weather' or 'too 

 much rain' for their sickly appearance. 



"If these lower plant forms are looked upon as weeds, it 

 will not be wondered at that there should be found in one 

 year hosts of new forms, some of which are living upon cul- 

 tivated plants and are hence of interest to cultivators. Thus 

 in a New Jersey cranberry bog a new fungous disease has 

 been found which forms upon the cranberry stems and leaves 

 thousands of bright rose-colored galls or swellings, checking 

 the growth of the plant and preventing fruiting.* Because of 

 the pronounced habit of the fungus of swimming from plant 

 to plant and bog to bog, it has seemed advisable to destroy by 

 fire the whole infected region to prevent the spread of the 

 trouble. The disease has been named the cranberry gall 

 fungus {Synchytriiini Vaccini, Thomas) and is so described 

 that any one will be able to recognize it. In Connecticut Dr. 

 Thaxter has discovered a new and destructive rot of the lima 

 bean, caused by a new species (^Phytophthora Phaseoli), allied 

 to the potato rot fungus, f which, if allowed to spread, may 



* Bull. 64, New Jersey Ex. Sta. 



t Annual Rep. Conn. Ex. Sta. 18S9. Jour. Mycology U. S. Dep. of Ag. Vol. vi. No. 11. 



