July i, 1918 
True Nature of Spinach-Blight 
7 
blight determined as follows: Typical blighted areas in several fields were 
selected, and soil borings made to determine the texture and condition 
of both surface and subsoil. Similar borings were made in the same 
fields in areas where the plants appeared healthy. In no case was it 
found that the drainage was poor where the plants were blighted, and 
in some cases the subsoil in these areas was such that the drainage was 
much better within the blighted areas than in parts of the field where 
the plants appeared healthy. This would indicate that the matter of 
drainage has little or no direct bearing on the cause or spread of spinach- 
blight. 
FERTILIZER EXPERIMENTS 
RELATION OF FERTILIZERS TO THE CONTROL OF SPINACH-BLIGHT IN 1915 
At the suggestion of Mr. T. L. Harter experiments were begun in 
which stable manure at the rates of 20 and 30 tons per acre and lime and 
gypsum at the rate of 1 ton to the acre were used in an attempt to de¬ 
termine the relation of these fertilizers to spinach-blight. Plots 0.1 acre 
in size were treated with the different substances, and similar untreated 
plots served as controls. The plots were planted with seed from the 
same lot and given similar cultural conditions. Spinach-blight developed 
as abundantly on the various treated plots as on the control plots; there¬ 
fore it would appear that stable manure, lime, and gypsum have no 
influence on controlling spinach-blight. 
# 
SOIL AND FERTILIZER EXPERIMENTS ON SPINACH-BLIGHT CONTROL 1 
The relation of soils and fertilizers to spinach-blight was unsettled 
previous to 1915; therefore cooperative experiments were begun. A 
series of plot experiments were outlined which was to include various 
individual fertilizer elements and also combinations of fertilizers and 
complete fertilizers made up on acid and basic principles. Forty plots 
were used in this experiment. Blight was equally abundant on all of 
the plots. No data were obtained to indicate that any of the individual 
elements or combinations of elements had any direct relation to the 
control of spinach-blight. 
Certain modifications of the above experiments were repeated in 
1916. These substantiated the 1915 results, that fertilizers have no 
direct relation to spinach-blight. 
RELATION OF FUNGI AND BACTERIA TO SPINACH-BLIGHT 
Although previous workers had obtained results which indicated there 
was no specific fungus or bacterium which was the cause of spinach-blight, 
nevertheless it seemed advisable to repeat this work. Blighted spinach 
plants were collected from various fields and from different areas in the 
1 Conducted in cooperation with the Office of Drug-Plant, Poisonous-Plant, Physiological, and Fer¬ 
mentation Investigations, Bureau of Plant Industry, United States Department of Agriculture. 
