16 MASSACHUSETTS HOETrCULTDRAL SOCIETY. 



which need not be described here. These fungi often attack the 

 floral organs of wheat and other cereals, distorting the grains or 

 "transforming them into masses of black dust consisting almost 

 entirely of the fungous spores. The familiar black masses 

 covered with a grayish integument which are often found upon 

 the stalks of corn, are caused by a species belonging to this 

 group of "Smuts." The Uredineae or "Rusts" are peculiar, in 

 that they not only may produce several forms of spores, but these 

 various forms usually occur on different host-plants and are 

 strictly limited to those plants. If the leaves of the barberry are 

 examined in the spring, they will often be seen to exhibit on their 

 lower surfaces small yellow pimples, several of which occupy a 

 spot a quarter of an inch in diameter. When these pimples are 

 mature they open and emit a yellow powder — the spores of the 

 fungus. Now should these spores fall upon a barberry leaf they 

 come to nothing; if, however, they are carried by the wind or 

 other agencies to the leaves of a member of the Grass Family, 

 they germinate, the mycelium traverses the leaf, and presently we 

 find the leaves streaked with a rusty color caused by the production 

 of quantities of pale yellowish spores. These in turn are 

 followed on the same leaves in autumn, by a black or very dark 

 brown form of spore, differing from either of the other forms and 

 yet belonging to the same fungus. Neither of these latter forms 

 can reenter the grass, but alighting upon barberry leaves the 

 3'ellow pimples are again produced in the spring. In like manner 

 the familiar brown lumps, called "cedar-apples," which we find 

 growing upon twigs of the red cedar and producing in the spring 

 yellow, gelatinous masses, constitute merely one stage in the 

 development of the fungus which produces the "rust" of apple 

 leaves. Such a condition of things has of course led to endless 

 confusion, and before the facts were known each stage received a 

 different generic and specific name. Even now, with our increased 

 knowledge, many mere form-species have to be retained as such, 

 until thorough investigation has completed our knowledge of the 

 life-history of the fungus in question. All these facts must be 

 taken into consideration in any rational treatment of fungous 

 disease. Thus, for example, we no longer recommend extensive 

 treatment of apple trees for " rust," knowing that the same end 

 can be readily and successfully attained by destroying neighboring 

 red cedars whose presence is absolutely essential to the develop- 

 ment of the " rust" fungus. 



