590 INSECTS AFFECTING VEGETATION 



from plant to plant and from field to field during the growing sea- 

 son. Another sort of spore is formed later, which being resistant, 

 serves to carry the fungus over the winter. These spores are borne 

 in minute sacks in the interior of a globose, or flattened, receptacle 

 called the perithecium. 



This disease is ordinarily of little importance, but under cer- 

 tain weather conditions may do considerable damage. Wet land 

 should be avoided, and care should be taken to avoid wind-breaks on 

 the south or east side of the field. Any condition favoring the reten- 

 tion of dew r on the leaves longer than is usual will favor the develop- 

 ment of this fungus. (Del. E. S. B. 83.) 



The Rusts of Grain. While the smuts of grains inflict great 

 losses upon the farmers of the country, they can be controlled by 

 careful methods, and the losses, in most cases, reduced to a minimum. 

 With the rusts, however, it is a very different matter, for they have 

 so far defied all fungicides, whether applied directly to the seed or in 

 the character of sprays. Another point about the rusts is that they 

 work much more insidiously. They manifest themselves in more 

 limited fruiting-areas on their hosts, do not directly attack the ker- 

 nels of grain, or even the heads, and are consequently neglected by 

 the most of our farmers or entirely misunderstood. Any farmer 

 sees that the smuts destroy his grain while on the stalk, and just so 

 far detract from his yield. Few of them on the other hand realize 

 that the rusts, which manifest themselves in little yellow, red, or 

 black spots on the culms and leaves of the grains, are just as surely 

 sapping the vigor and detracting from the yield of his crop as if 

 they took the grain itself for their places of reproduction instead 

 of the stems and leaves. And it is remarkable how little attention 

 is paid in many places to those little plunderers. Rusts are very 

 common in Idaho, and it is doubted whether a section of wheat 

 can be found that is not more or less affected. If they are so com- 

 mon, how can they best be combatted? (Idaho E. S. B. 11.) 



Some of the treatments used are the following, when a field 

 has shown abundant rust: 



1. Let it lie fallow for a year, or, where such is possible, put 

 it into some other crop than a cereal. One year's cultivation will 

 kill out all the spores remaining on the ground, as will a year's 

 summer fallow if all volunteer wheat is plowed under. 



2. If such fallow land is not to be plowed, then pasture closely 

 to keep down any vegetation upon which the rusts can get a hold. 

 They flourish nearly equally well on grasses. 



3. Where the person cannot afford to summer-fallow land, if 

 such a state of affairs be admitted, and a cereal must be followed 

 next year by a cereal, burn over the stubble, burn all piles of in- 

 fected straw (as they will infect the field, and are unfit for food for 

 stock), and haul out upon the farm no poorly-rotted and therefore 

 possibly smutted or rusted straw. 



4. All wheats suffer from rust, but the early ripening ones 

 suffer least; therefore where rust is abundant plant early varieties, 



