580 INSECTS AFFECTING VEGETATION 



or yellowish colored spots, upon which the dark colored spores of the 

 fungus are produced. 



After a time the entire leaf is so affected that it dies, although 

 often only the tips are diseased. The general appearance of a dis- 

 eased field resembles very much one that has been frost bitten. The 

 fungus occurs early in the growing season, July and August, but 

 thus far it has never been reported as injuring corn seedlings. This 

 disease has the power of killing the partially matured plant. This 

 means a shorter growth and immature stalks. It not only causes 

 less amount of fodder, but if intended for ensilage the corn is likely 

 to die before the farmer would think of cutting it, so he has dead dry 

 fodder instead of green for his silo. If the corn is intended to pro- 

 duce ears the disease so weakens the vitality of the plant as to prevent 

 proper maturing of the crop. 



The disease occurs at such an advanced stage in the growth of 

 the corn that at present no remedy seems practical. In all proba- 

 bility the spores would live after passing through the ailmentary 

 canal of an animal and so spread the trouble the following year. It 

 seems advisable, if the corn was diseased the previous year, not to 

 use manure made from it on land intended for corn. A rotation of 

 crop is also advised. (Del. E. S. B. 63.) 



Corn-Smut. Every farmer is familiar with corn-smut. The 

 largest masses are sometimes over 6 inches in diameter and are usu- 

 ally found in the ear. Smut is also found in the tassel, on the leaves 

 and stem, and even on those roots which hold the corn-plant to the 

 soil. The smut-mass is blackish, and is at first covered by a whitish 

 film, which soon breaks and lets loose the spore-powder, which is 

 blown about by the wind. How, by these spores, the disease lives 

 through the winter, and then gets into the corn-plant, has been de- 

 scribed above. In general, there are two ways by which the spores 

 get back on the land, ready to infect the next year's crop. First, 

 they may be scattered by the wind, or the smut-masses may be left 

 on the field. Second, the smut-dust may get into the fodder and may 

 pass through the ailmentary canals of the cattle, without being in- 

 jured, and may thus get into the manure-pile. Or again, the smut- 

 masses may be thrown into the refuse or manure-pile. In either 

 case they may be carried back to the soil when the latter is manured. 

 Now, it is an important fact that the smut spores not only may live 

 through the winter in the manure-pile, but that they may actually 

 increase in number by growth when the pile remains of proper tem- 

 perature. Fresh manure containing smut is therefore very likely to 

 increase smut in a corn-field. The smut may live for several years 

 in a manure-pile, but will gradually die out. For this reason, old 

 manure is much better for fertilizer on a corn-field than fresh 

 manure. 



Since the smut-masses that are left in a corn-field may assist 

 in spreading the disease, they should be cut out of the corn-field 

 during the growing season. They should, moreover, be cut out be- 

 fore they have fully opened up and spread their spores, and should 



