.4
35 Thir2‘y-Fifth Annual Report. _ .
A single seed piece cut from each tuber was planted in a
hill in early April -and the remainder of each tuber, all being '
carefully numbered, placed in cold storage for summer plant-
ing for the second crop. Exact records were kept of growth
and yield. Every hill showing signs of mosaic infection
, (varying from a trace to 95 per cent) was noted and the corre-
sponding numbered seed piece held in storage was eliminated,
the remainder being planted in July for the second crop.
No mosaic appeared in any of the several hills planted from
each tuher of the selected stock. Again a single tubcr from
· each hill was planted at the spring of 1922 and like records
. obtained. No mosaic appeared in any of these spring planted
hills. The remainder of the apparently mosaic-free stock was
held in storage and planted in July of this year for the second
_ . erop. tionsiderable leaf roll and a few plants of low vitality
appeared in this second crop. It appeared, however, that
inosaie had been completely eliminated in two seasons from
· seed stocks whieh at the beginning had been infected in vary-
ing degrees from 2 to 95 per cent.
Lettuce Variety Tests. A strain of Grand Rapids, called
No. lt). was selected in 1921 and has been found more uniform
and vigorous than the ordinary Grand Rapids obtained from
seedsmen. The selections from heading varieties have not
shown as marked improvement as was desired. The Hanson
and New York or \Vonderful have been found the most reli-
able heading sorts up to the present either for garden or green-
house.
Lettuce Root-Rot and Tipburii. Several lots of apparent-
ly normal lettuce seeds have been tested for seed-borne organ-
isms. ln some lots nearly every seed appeared to be infected
with JIuri·o.vp0riunv. sp. as indicated by the outgrowth of this
organism from surface sterilized seeds grown on a sterile moist
blotter. Other lots of seed appeared to be free from any infec-
tion when tested under these conditions but when mierotome
seet ions ofthe seeds were made and properly stained, very small
stands of a fungus could be seen lying between the seed-coat