IO CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



it then follows the upward growth of the plant, often not giv- 

 ing evidence of its presence until it breaks out in its spore 

 stage in the fruiting organs of the host two or three months 

 later. This is the case with the oat smuts, wheat and barley 

 smuts, and the grain smut of broom-corn. In this latter case 

 the mycelium has traveled upward through six to ten feet of 

 the cane. In other species infection may take place, through 

 any very young tissue of the host upon which the germs may 

 be blown or washed into contact. This is the case with corn, 

 and the corn smut appears soon after infection in its smutty 

 outbreaks, the mycelium usually remaining localized. With 

 the Entylomas the infection is largely confined to the leaves, 

 and apparently the mycelium is limited to the vicinity of the 

 sorus. 



ECONOMIC IMPORTANCE. 



Injury. While most of the smuts occur on plants of no 

 economic importance, there are at least twenty-five species in 

 America that do more or less injury to cultivated plants. Some 

 of these cause such serious injury that they are counted among 

 the worst species of parasitic fungi. It is with the cereals that 

 the smuts do most damage. Wheat, oats, barley, rye, and corn 

 are all subject to attacks from one or more species. With the 

 first three hosts the smuts break out in the inflorescence, en- 

 tirely preventing the formation of the seed. It thus becomes 

 an easy matter to determine rather accurately the per cent, of 

 loss in fields of these grains by counting the number of smutted 

 and of free heads in a given area. Oat smut, for instance, in 

 our central states generally claims from one to fifteen per 

 cent, of the grain, and in some few fields as high as thirty or 

 forty per cent, has been destroyed. In Illinois there is perhaps 

 an average loss per year of one million dollars worth of oats, 

 caused by the two smuts of this plant. In Indiana Arthur 

 found one field of wheat where fifty per cent, of the grain was 

 destroyed by the stinking smut. In the northwestern states, 

 in the wheat districts, the loss caused by this latter smut is 

 very great, as it is one of their worst fungous pests. When 

 abundant it renders the grain inferior for milling purposes, as 

 the spores may be so numerous in the flour that they darken 



