STUDIES ON FOOT- AND ROOT-ROT OF WHEAT: VI. METHODS OF SECURING INFECTION OF WHEAT SEEDLINGS FOR STUDY IN NUTRIENT SOLUTIONS

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Abstract
The two foot-rot diseases of wheat caused by Helminthosporium sativum P. K. & B. and Fusarium culmorum W. G. Sm. were studied in nutrient culture solutions instead of in the usual substrates of soil or sand. The most satisfactory results were obtained by first germinating the grains in a specially designed tray, then securing infection of the young plants by adding inoculum to the tray, after which the seedlings were transplanted to the nutrient culture solution. Infection of the seedlings was distinctly increased when sucrose was added to a nutrient solution infested previous to the time of transplantation. Infection was less satisfactory when the seed was immersed in a spore suspension, dried, and germinated on the tray. Very unsatisfactory infection was secured by adding a spore suspension in water, with or without sugar, to the nutrient solution at the time of transplanting the seedlings. Inoculating the seedlings with a spore suspension by means of a hypodermic needle produced practically no infection. Length of shoot, and particularly the dry and the green weight of the entire plant were reliable quantitative criteria for the evaluation of disease. The first method indicated appears to offer several important advantages in that the degree of infection can be controlled.