246 



THE CEREALS IN AMERICA 



called the corn-stalk disease. The first indication of the disease is the dwarfed 

 condition of the young plant. This commonly occurs in spots of various sizes, 

 and is found in rich places, rather than in those of poorer quality. The young dis- 

 eased plants, besides being smaller than the healthy ones, are uniformly yellowish 

 in color, the lowest leaves showing worst. Affected plants are easily pulled from 

 the ground on account of the death of the lower roots. The inner tissue of the 

 lower part of the stalk has a uniform dark color, while on the surface there are 

 brownish corroded spots. After midsummer the leaf-slioaths become spotted with 

 various sized patches of a watery-brown, half rotten in appearance, which are most 

 conspicuous from the inner surface. The ears are at Isast occasionally affected. 

 Internally, in the worst stage, the whole ear is reduced to a moist state of corruption. 

 Very often these ears subsequently become mouldy, penetrated through and through 

 by a close, very white, felt-like fungus. These mouldy ears are, in certain seasons, 

 very numerous, and are readily recognized by the husker. No remedy is known. 

 There appears to be in a considerable number of cases more injury on land which 

 has been planted with maize the preceding year. 



324. Bacterial Disease of Sweet Maize. — Plants affected by this dis- 

 ease wilt and dry up very much like plants suffering from lack of moisture, except 

 that there is little or no rolling of the leaves. Diseased plants are intermingled 

 with healthy ones. The woody strands of the plant are filled with a multitude of 

 short, yellow bacilli, which, when the stem is cut across, exude 

 as a yellow viscid substance. The disease is confined to sweet 

 maize, and is most destructive to early varieties. It is dissemi- 

 nated chiefly by means of the germs which cling to the seed. No 

 remedy is known. The principal measures of prevention are 

 selection of seed and the planting of resistant varieties. 1 



325. Maize Rust is found wherever maize is grown, but 

 principally in regions of considerable rainfall. The rust does not 

 differ materially in appearance from rusts of other grasses, par- 

 ticularly Puccuiia grarninis of wheat and oats; the surface of the 

 affected leaf and sheath displays small oblong or elliptical spots, 

 which contain reddish-brown spores. Kellerman has sho^\T^ that 

 only the uredo and teleuto stages may be included in the life 

 cycle, although Arthur has identified the aecidial stage on oxalis. 2 

 It passes the winter in the teleuto stage. Though fungicides are 

 effective, the rust is of such little economic importance as not to 

 warrant treatment. Pammel reports decreased yields of sweet 

 maize due to the rust. The rust also occurs on sorghum and 

 teosinte. 



326. The Leaf Blight Fungus has been reported in 

 maize, causing extended or elliptical brown (dead) areas in the 

 leaf blades, not distinguishable by the unaided eye. The disease 

 is of little economic importance. 



1 N. Y. (Geneva) Bui. 130. 



« Botanical Gazette, July, 1904. 



Uredo stage or red 

 rust on maize 

 leaf. Disease 

 produced by in- 

 oculation by 

 Kellerman 



