BUREAU OF PLANT INDUSTRY. 199 



The rolled dolls are placed in a double-walled box and kept at the 

 proper conditions as to temperature and moisture during germina- 

 tion. The use of the table germinator has been found satisfactory 

 where the necessary equipment is available. 



An extensive study of different varieties and strains of dent and 

 sweet corn is under way at several places. Different strains of Reid's 

 Yellow Dent are being grown in parallel rows at two points in 

 Indiana, and marked difl'erences in susceptibility apparentl}- exist in 

 different strains. 



Breeding experiments in Indiana show that tendencies toward sus- 

 ceptibility can be concentrated b}' selfing ears on diseased plants. 

 Resistance and susceptibility appear to be inherited characters. 



The most important result from the standpoint of control measures 

 is the fact that a high percentage of the diseased or predisposed seed 

 ears can be detected by their j)hvsical characteristics and so discarded 

 from the seed stock. The physical characteristics are of two classes : 

 (1) Those of the kernel and (2) those of the ear-shank attachments. 



It was found that the most susceptible corn plants resulted from 

 kernels either immature or unduly starchy and with very rough dent- 

 ing. Vice versa, the most nearly disease-free seed and that producing 

 plants showing the highest degree of resistance was found- to be 

 horny and bright in appearance and with rather shallow denting. 

 The healthiest ears are those whose ear-shank attachments do not 

 show cracking, shredding, discoloration, or any evidence of moldy 

 growth when the outer end is cut off with a sharp knife. The ear- 

 shank attai hments of the best ears are rather firm and clean. A 

 description of control measures that may now be applied by farmers 

 has been prepared for publication. 



FUSARIUM BLIGHT, OR SCAB, OF WHEAT AND OTHER CEREALS. 



Losses caused. — It is estimated that this destructive disease* caused 

 almost as heavy losses of wheat in 1919 as did the black stem rust. 

 The loss of cereal crops, due to blight, or S( ab, is estimated to be ap- 

 proximately 59,081,000 bushels of wheat, 927,000 bushels of barley, 

 39,000 bushels of rye, and a considerable quantity of oats not defi- 

 nitely estimated. The total estimated loss was a little over 00,000,000 

 bushels of grain. The disease w^as distributed practically throughout 

 the ^Mississippi Valley and eastward to the Atlantic coast, but was 

 most severe in the corn-belt States. 



Host plants. — The disease attacks all the cereals and a number of 

 other grasses. Various organs of the host may be attacked by the 

 disease, principally the heads, but also the root systems and bases of 

 the stems of seedlings. 



Causal fungi. — Extensive investigations show that several differ- 

 ent fungi produce Avheat scab, but that Oihherella sauhhietil causes 

 the major losses. It also is one of the causes of corn rot in the corn 

 belt. In a series of studies made from over 1.000 specimens of 

 scabby wheat from 15 States, this fungus was found to be the pre- 

 dominating organism present. Less than 1 per cent of the specimens 

 yielded Fusdiimri culniunini., F. avenacenm. and other Fusarium 

 species. 



Sources of infection. — It was found that the most important source 

 of infection for wlieat blight, or scab, was old cornstalks carrying the 



