34 BULLETIN 759, U. S. DEPARTMENT OF AGRICULTURE. 
plants were known to exist within a 5-mile radius the results have 
been included. 
TasLteE VIII.—Summary of data of plat tests to determine whether leaf-spot can 
be prevented on alfalfa sown in isolated localities by the superficial steriliza- 
tion of alfalfe seed. 
me a Distance 
r ate ate é oO nearest 
State and town. sown. visited. (square alfalfa Leaf-spot. 
rods). : 
(miles). 
Maine: 1915. 1916. 
INE CECT Ns me tse ee are fe ee oO Ree OLSEN Ne june 2S June 14 1 6 | Present, 
1916. 
WAN Fo OTT ae cree Roe ayaa a SL SOT Re ie May 6 | Sept. 12 20 3h Do. 
Fairfield.....-- EUS Ey aA Set eke NEE aid ey AUS TN pac atat ad une sees pee doz=s=5 40 5 Do. 
1 4 Do. 
2- 34 | Doubtful. 
40 5 | Present. 
40 5 Do. 
IBTUCOH IS 2 Nes 3 oe ERE Se epee May 20} Aug. 11, 40 5 Do. 
Wisconsin: 
I OGriN ge 742755 Hear SER Ed Se he See ee alte June sss| OCtan 2 40 10 | Doubtful. 
INRA CONN Se oacenoecoonseseoobsssouessucedes May..--- Oct. 4 10 4 | Present, 
Radisson sos icke Mees as sie Date eee Eee June. -..|-.. do...-- 40 3 Do. 
IM@rrilest snake ahi: it ROR SUN TC RN eta ety Eee Omenae Octa 2 40 5 Do. 
D GOs a |/s22dOs-s4- 40 8 Do 
CW accsellese 6asao0 40 124 Do. 
dos ieee 6lOc656 40 10 Do 
do O22 40 10 Do 
do Oct. 5 40 5 Do 
From Table VIII it appears that the one small well-isolated plat 
started in 1915 did not develop leaf-spot until the following year. 
Of the 16 plats started in 1916 only 2 failed to show an abundance 
of leaf-spot in the autumn of the same year. One of these plats, 
located at Harrison, Me., was in very poor condition, only a few 
scattering spindling plants about 4 inches high being found. How- 
ever, other plats in almost as poor condition showed leaf-spot. The 
second doubtful plat, at Doering, Wis., was in very vigorous con- 
dition, but it had been cut just previous to inspection, leaving very 
little foliage. Unfortunately, it was not feasible to revisit the plat 
the following year. 
These results are in accord with previous experiments and experi- 
ence. Surface sterilization of seed apparently accomplishes nothing 
in excluding leaf-spot from alfalfa fields. But these results do point 
very clearly to one conclusion, that the leaf-spot fungus is not car- 
ried on or in débris mixed with the seed. The greenhouse experi- 
ments, which are only suggestive because of their limited extent, 
indicate that the fungus is not carried within the seed. 
Thus, in conclusion, it is necessary to say that no positive evidence 
pointing toward the method by which this disease gains access to 
remote alfalfa fields has been found. Evidence has been obtained 
which apparently eliminates other plants previously under suspicion 
as host plants of the fungus from consideration as sources. A lim- 
