146 
AMERICAN JOURNAL OF BOTANY 
[Vol. 10, 
Plants growing in soil with a very low moisture content lost their disease 
resistance if a rapid, vegetative type of growth was induced by the addition 
of sufficient water to keep the soil moist. 
Plants growing in saturated soil were immune to attack, but if the mois¬ 
ture content was lowered the disease soon developed. 
The immunity of the saturated soil plants was apparently correlated 
with the practical absence of nitrates in the host tissues. 
New York Agricultural Experiment Station, 
Geneva, New York 
LITERATURE CITED 
1. Appel, O. Uber bestandweises Absterben von Roterlen. Naturw. Zeitschr. Land- 
11. Forst. 2: 313-320. 1904. 
2. Bergman, H. F. The relation of aeration to the growth and activity of roots and its 
influence on the ecesis of plants in swamps. Annals Bot. 34: 13-33. 1920. 
3. Clayton, E. E. The relation of temperature to the Fusarium wilt of the tomato. Amer. 
Jour. Bot. 10: 71-88. 1923. 
4. Coleman, D. A. Environmental factors influencing the activity of soil fungi. Soil 
Sci. 2: 1-65. 1917. 
5. Fowler, L. W., and Lipman, C. B. Optimum moisture conditions for young lemon 
trees on a loam soil. Univ. Cal. Publ. Agr. Sci. 3: 25-36. 1917. 
6. Harris, T. S., and Maughn, H. I. The effect of soil moisture content on certain factors 
in wheat production. Utah Agr. Exp. Sta. Bull. 152. 1917. 
7. Hole, R. S. Recent investigations on soil aeration with special reference to forestry. 
Jour. Agr. India 13: 430-440. 1918. 
8. Humbert, J. G. Tomato diseases in Ohio. Ohio Agr. Exp. Sta. Bull. 321. 1918. 
9. Johnson, J. Influence of soil environment on the root rot of tobacco. Jour. Agr. 
Res. 17: 41-86. 1919. 
10. Kiesselbach, T. A. Transpiration experiments with the corn plant (preliminary 
report). Ann. Rept. Nebr. Agr. Exp. Sta. 23: 125-139. 1910. 
11. Koehler, B. Relation of soil moisture to seedling blight of wheat caused by Gibberella 
saubinetii. M.S. thesis, on file in the library of the University of Wisconsin. 1920. 
12. Livingston, B. E., and Hawkins, L. A. The water relations between plant and soil. 
Carnegie Inst. Wash. Publ. 204. 1915. 
13. Peltier, G. L. Parasitic Rhizoctonias in America. Ill. Agr. Exp. Sta. Bull. 189. 1916. 
14. Rolfs, F. M. Report of the Horticulturist. Ann. Rept. Fla. Agr. Exp. Sta. 1905: 
29-47. 1905. 
15. Waksman, S. A., and Cook, R. C. Incubation studies with soil fungi. Soil Sci. 1: 
275-284. 1916. 
EXPLANATION OF PLATES 
Plate XIII 
A. A series of plants growing in sterilized, uninoculated soil with soil moisture ranging 
from 15.5 to 35 percent (saturation). At 32 percent, the maximum wet weight and the 
maximum dry weight of tissue were secured; the percentage dry weight, however, was the 
lowest at this percentage of moisture. The plants growing with 15.5 percent moisture 
were low in total weight but high in percentage dry weight. The plants growing in 
saturated soil (35 percent soil moisture) were low both in total weight and in percentage 
dry weight. 
B. Plants grown in soils inoculated with Fusarium lycopersici at the same time as the 
plants of the check series (^ 4 ), the soil moistures used in the two series being the same. 
