RUST RESISTANCE IN WINTER-WHEAT VARIETIES. 15 
sceptible variety. The inoculation method used was described by 
Melchers (25) and was a modification of the method proposed and 
used by Kellerman (22) and Carleton (7) in their studies of cereal 
_and other rusts. This is a satisfactory method where the supply of 
rust is limited, as there is little chance for loss of spores. The spore 
supply was collected in a Petri dish and applied to the seedlings by 
means of a flattened or a rounded needle. The leaves to be inocu- 
lated were first thoroughly dampened by stroking them several — 
times between the fingers previously. moistened in water. Tap 
_water was used with satisfactory results, although Melhus and Dur- 
_ Yell (32) have shown that tap water may have a toxic effect on the 
germination of certain kinds of rust spores. 
In the studies in the greenhouse the seedlings were grown in 24-inch 
pots, illustrated in figure 2. Fifteen pots, each containing 2 seed- 
lings, or 30 seedlings in all, constituted one series of each variety. 
Fic. 2.—Seedlings grown to determine rust resistance of wheat varieties under greenhouse conditions. 
Pots 1 and 2 contain seedlings of a susceptible variety used as a check; Nos. 3 to 6 contain seedlings of 
P1068. Each of the two Seedlings in each pot is trimmed to a Single leaf blade which is inoculated. 
In most cases it was not necessary to inoculate more than one series 
of plants, but if the results were at all doubtful a second series was 
inoculated. Hundreds of inoculations were made on seedlings of 
Kanred, P1066, and P1068. Two to four seedlings of Improved 
Turkey (Kansas No. 2382) were used as checks for each series. 
After inoculation, the seedlings were kept in damp chambers for 
48 hours, after inch they were removed and placed on the green- 
house bench. Bell jars were first used, but these proved impracti- 
cable. An inexpensive and effective damp chamber, shown in 
Plate VII, was devised. It consisted of a galvanized-iron washtub 
with a pane of glass for a cover.® 
About one-quarter of an inch of water was placed in the bottom of 
each chamber, to keep the air saturated. ‘The chambers were kept 
in the shade, so as to maintain a temperature of 50° to 70° F. In 
warm weather, a spray of water was directed upon the damp cham- 
bers to reduce the temperatures. Difficulty was experienced during 
9 Cylinders made of galvanized iron (without permanent top or bottom), with a diameter of 15 inches 
and a height of 12 inches, have been used more recently. A removable piece of glassis used foratop. If 
these cylinders stand on damp sand, sufficient moisture is supplied to keep the chamber saturated, and 
the potted seedlings do not stand in water. Damp chambers of this type have proved very Satisfactory. 
