862 
Journal of Agricultural Research voi. xxvn, No.« 
WHEAT SCAB IN RELATION TO PREVIOUS CROPPING 
REVIEW OF LITERATURE 
Latta, Arthur, and Huston (15) , 2 in 1891, mentioned the prevalence of 
scab on a plat where wheat had been grown continuously and on an ad¬ 
jacent plat where wheat and com had been grown alternately for 11 
years* This seems to be the first recorded observation on the relation of 
previous cropping to the occurrence of wheat scab. In 1909, Selby and 
Manns (19) also recorded observations on the relation of previous crop¬ 
ping to the production of wheat scab. They noticed that on the experi¬ 
mental plats that had been sown to wheat continuously for a number of 
years scab was worse than on the plats where the crops had been rotated. 
Some years later Bolley (j) emphasized the importance of rotating wheat 
with some other unrelated crop to keep down wheat scab. He recom¬ 
mended rotating with clover, alfalfa, grasses, potatoes, flax, and com. 
In 1918, Hoffer, Johnson, and Atanasoff (8) reported that there was a 
greater abundance of wheat scab in fields where wheat was grown im¬ 
mediately following com that was infected with the Fusarium root and 
stalk rots. They found that wheat-scab infection may take place 
from Gibberella spores growing on old diseased cornstalks and that corn 
rootrot can be produced under laboratory conditions by Gibberella 
spores isolated from scabbed wheat. During the same year Hoffer and 
Holbert (7) reported a greater amount of scab when wheat was sown in 
infested com fields. 
In 1919, Holbert, Trost, and Hoffer (zz) reported on the occurrence of 
wheat scab as affected by crop rotations. Their observations, which cov¬ 
ered 28 fields, comprising 1,500 acres, confirmed previous observations 
that wheat following com is scabbed more severely than that following 
any other crop. 
Since then, reports have appeared by Johnson and Haskell (14, p. 
24-26), Johnson and Dickson (73), Fromme (6, p. 141 ), and Adams (1) 
stating that wheat-scab infection is heaviest when wheat follows a corn 
crop. 
survey of 1919 3 
In 1919 counts were made of wheat-scab infection following various 
common crops in seven different States. There was an unusual epidemic 
of scab during this season. Most of the wheat examined was in the hard- 
dough stage and some of it was ripe. Each percentage determination 
was made by counting a hundred heads along a drill row and breaking 
off all heads that showed the presence of scab. The number of scabbed 
heads picked off then gave the percentage of infected heads. At the 
close of each day, the heads thus collected were sent to the laboratory at 
Madison, Wis., for identification of the organisms. In making the scab 
counts, four or more, and often over a hundred, percentage determina¬ 
tions were made in different parts of each field. 
In Wisconsin, where the grain had recently been cut, the percentage 
determinations were made from entire bundles. From four to nine 
bundles were selected from different parts of each field, each bundle 
containing over 2,000 heads. 
* Reference k made by number (italic) to “literature cited," pp. 878-879. 
3 L,. E. Compton, Junior Pathologist, Office of Cereal Investigations, Bureau of Plant Industry, U. S. 
Department of Agriculture, assisted in obtaining these survey data. 
