STUDIES ON FOOT AND ROOT ROT OF WHEAT: V. THE RELATION OF PHOSPHORUS, POTASSIUM, NITROGEN, AND CALCIUM NUTRITION TO THE FOOT- AND ROOT-ROT DISEASE OF WHEAT CAUSED BY HELMINTHOSPORIUM SATIVUM P. K. & B.
The effect of different amounts of phosphorus, potassium, nitrogen, and calcium upon the development of the foot-rot disease of wheat caused by Helminthosporium sativum P. K. & B. was studied in the greenhouse. The wheat grains were planted in sterilized pure quartz sand to which the necessary nutrients and spore suspension of the pathogen were added. The experiments were maintained under aseptic conditions during the first ten days. The disease increased when the ionic concentration of potassium, nitrogen, and calcium was decreased below that of the complete nutrient solution, but no significant reduction of the disease was observed when the concentrations of all of the elements, including phosphorus, were increased above those in the complete nutrient solution. Apparently extremely small concentrations of phosphorus had no effect on the disease one way or the other. These conclusions apply to the disease on the seedling stage of wheat.