FigT. 1. Reproduction of the color plate XYIII of corn smut by Bonafous in 1836 (25). A translation of Bonafous' 

 legend to this plate (objects from left to right) follows: Fig. 1. Ear with many kernels which have become mon- 

 strous and deformed by the effect of the smut. Fig. 2. No. 1, 2, 3, 4, 5, 6, 7. Different kernels of corn still recognizable 

 and variously affected by smut: we see that they can be attached from above, from below, from the sides, and in 

 many places at the same time. Fig. 3. No. 8, 9, 10, 11. Here, the kernels of corn have entirely lost their form; and 

 the progress of the smut, by increasing their volume and by deforming them, has transformed them into hollow 

 bodies filled with fibers and black powdery grains; No. 11 wh'ch is a horizontal section, shows the interior aspect 

 of one of these bodies which has become monstrous. Fig. 4. Another section showing the same interior aspect. 

 Fig. 5. Here, a smutted kernel is beginning to decompose. It is remarkable that the smut is able to produce an 

 appearance of fibrous tissue in a corn kernel which, in its normal state, only has a cellular tissue. Fig. 6. A small 

 mass of decomposed cellular tissue from a monstrously developed kernel whose elementary body or globulin, according 

 to M. turpins system, has increased in volume and passed from a white color to a brown color. Fig. 7. Sometimes, 

 a few of the vesicles in which the altered globulin is distinguished are still found (a) a ruptured vesicle with escaping 

 globulins. Fig. 8. A smutted globulin, enlarged. Fig. 9. A vesicular globule still more enlarged, in the interior of 

 which we see some very fine granulations, with a more opaque circle which indicates the thickness of the vesicle. 

 Fig. 10. A portion of tissue taken in a healthy leaf and in which we find in (a) the epidermis or cuticle, trans- 

 parent and colorless membrane; (b) a very elegant network composed of a filament arranged in a zig-zag; (c) sto- 

 mata ; (d) vesicles containing an abundant, green globulin which is capable of altering itself and of converting 

 itself into the black dust of the smut; (e) a ruptured vesicle with the escaping globulin. The two envelopes of the 

 kernel, in becoming monstrous and in taking a sac-like development also give rise to a black smutted globulin. The 

 diameter of the smutted globulin is 1/200 of a millimeter. Like all the diseased globulin, these globules are remarkable 

 by the uniformity of their size. (Transl. by Claude C. Bernier.) 



In 1836. Unger (340 I recognized it as a fungus and 

 named it Ustilago zeae. Until recent years, this name 

 was used most extensively by most investigators. In 

 1944. Stevenson and Johnson (326) stated that U. 

 maydis (DC.) Cda. is the correct binomial, according 

 to the International Rules of Botanical Nomenclature. 

 This binomial is currently used by most plant pathol- 

 ogists (98). 



The synonyms for U. maydis were taken primarily 

 from publications by Clinton (61), Fischer (96), and 

 Stakman (305). 



Syno7iy my. —Ustilago maydis (DC.) Cda.. Icones 



Fung. 5:3. 1842. 

 Ustilago carbo-maydis Phillipar.. Traite Caris Charbon 



68. 1837. 

 Ustilago maydis Lev., Ann. Sci. Nat. II. 11:13. 1839. 

 Lycoperdon zeae Beckm.. Hannov. Mag. 6:1330. 1768. 

 Uredo segetum var. mays-zeae DC, Fl. Fr. 2:596. 1805. 

 Uredo zeae-mays DC, Syn. PI. Fl. Gall., p. 47. 1806. 

 Uredo segetum f. zeae-maydis DC. Encycl. Meth. 



Botan. 8:229. 1808. 

 Uredo maydis DC. Fl. Fr. 6:77. 1815. 

 Uredo zeae Schw., Schr. Nat. Ges. Leipzig 1:71. 1822. 

 Caeoma zeae Link., Sp. Plant. 2:2. 1824. 

 Erysibe maydis (DC.) Wallr.. Fl. Crypt. Germaniae 



2:215. 1883. 

 Ustilago zeae (Schw.) Ung., Einfl. Bodens, p. 211. 1836. 

 Ustilago schweinitzii Tub, Ann. Sci. Natl. Botan. 7:86. 



1847. 

 Ustilago zeae-mays Wint.. Rabh. Krypt. Fl. 1 :97. 1881. 

 Ustilago euchlaenae Archang.. Erb. Critt. Ital. 2:1152. 



1882. 

 Ustilago maydis (DC.) Cda. f. joliicola Sacc, Mycol. 



Ital. 1269. 1886. 

 Ustilago maydis f. androphila D. Sacc. Mycol. Ital. 



1270. 1886. 



Host Range. — As far as is known, U. maydis attacks 

 only 2 species of plants: Indian corn (Zea mays L.) 

 and teosinte (Euchlaena mexicana Schrad. ). 



Losses. — Corn smut caused by U. maydis is virtually 

 world-wide in distribution. It may be found wherever 

 corn is cultivated, except in Australia. About 50 years 

 ago. U. maydis was introduced into Australia, but it has 



been eradicated (207). Apparently, corn smut is most 

 destructive in the U.S. where it often causes severe 

 losses (78, 160, 170. 341. 351). 



A survey of literature indicates that there have been 

 marked fluctuations in the prevalence and economic 

 importance of corn smut in the U.S. Unfortunately, in 

 many cases, only the prevalence of smut is given and 

 not the losses caused by it; this is especially true of 

 the early reports. 



The economic importance of corn smut was not fully 

 recognized until the latter part of the nineteenth cen- 

 tury. Losses in Wisconsin in 1881 were given as 5-15% 

 for individual fields (132). In 1884, Bessey (19) in- 

 dicated that corn smut losses in Iowa were about 2% 

 of the crop. He reported the loss for 1 field of sweet 

 corn at 66%. In 1897, Selby and Hickman (298) re- 

 ported fields in Ohio that contained 25-45% smut- 

 infected plants and indicated the loss to be about 

 4.4% of the crop. Clinton (60), in 1900, estimated the 

 loss in Illinois at 0.5-5.0%. The average annual loss in 

 Illinois between 1917 and 1937 is given as 2.3 C / C (341 ). 



In 1896, Hitchcock and Norton (143) estimated the 

 average corn smut infection in Kansas at 6%. Twenty- 

 nine years later, Potter and Melchers (267) reported 

 that fields in eastern Kansas with 30-50% smut-infected 

 plants were not uncommon and that fields with 60- 

 80% infected plants were common in semiarid regions 

 of Kansas. It was their opinion that smut infection had 

 become much more prevalent during the decades be- 

 tween 1900 and 1930 than it was previously. Until the 

 development of resistant or semiresistant hybrids, fields 

 of open-pollinated corn with 25-50% infection were not 

 uncommon (78, 80, 158, 328). In Minnesota, some fields 

 occasionally had more than 70% smutty plants. Today, 

 although more than 700 hybrid varieties are grown in 

 Minnesota, one seldom encounters fields with more 

 than 5 or 10%. infection, usually much less. Smut is 

 still a destructive disease on sweet corn. It not only 

 reduces yield, but adds to difficulties and cost in 

 processing of sweet corn. 



From 1918 through 1924. the annual loss in yield 

 from corn smut in the U.S. was about 2.1% (341). 

 During the 1920's. smut losses ranging from 5 to 10% 



