Field Note. 
153 
to show the benefits which can accrue to English growers 
of potatoes, through using virus-free seed. 
Through the courtesy of Messrs. Jackson Brothers, Farmers, 
of Thorpe fields, near Thirsk, Yorks., a held was planted 
with alternating plots of ordinary fresh Scotch seed and 
Stock seed (called by them ‘ pedigree ’). Each plot was 
4! sq. chains in extent, and was separated from its neighbours 
by a belt of oats twenty feet wide. For comparison, about 
an acre was planted with seed thrice grown in the neighbour- 
hood of Thirsk. The variety was Arran Consul, and the 
different plots were planted at the same time. 
The ‘ Pedigree ’ (Stock) Scotch seed produced a crop 
which had, on an average, one virus-diseased plant in every 
long row (about 270 ft.). The ordinary Scotch seed had 22 
diseased plants in the same length, whilst the thrice grown 
seed had 95 virus-infected plants per row. These differences 
are reflected in the average yields (expressed in tons per 
acre) 
TABLE III. 
Ordinary Scotch ‘ Pedigree * (Stock) 
Thrice grown. seed. seed. 
6 tons 10 cwt. p.a. 11 tons 4 cwt. p.a. 12 tons p. a. 
There is thus an increased yield of 16 cwt. per acre due to 
the relative freedom from virus disease. The few diseased 
plants were removed from the Stock Seed plots, so that seed 
from them should be still relatively free from virus next year. 
Experiments at Weetwood, Leeds, show that virus-free 
stocks of potatoes can be planted year after year in Yorkshire 
without diminution in yield. 
New Stock seed costs a pound or two more per ton than 
ordinary Scotch seed, but with reasonable care in rogueing 
the few diseased plants which occurr, it can be grown for at 
least twice as long as ordinary seed in a lowland area. More- 
over, the increase in yield due to freedom from virus will be 
felt each year. The use of Stock seed is a commercial 
proposition. 
It must be remembered that virus-free seed is also produced 
in the northern districts of Ireland, and the same remarks 
apply with equal force to seed from that source. Lists of 
growers of Stock seed are published by the respective Depart- 
ments of Agriculture in Belfast, Dublin and Edinburgh. 
Gagea Lutea. — Two specimens of Gagea lutea have been 
found in a field on the east of Ripon Race-course. This is the 
first time in ten years that it has been brought to me from any 
spot to the south of the town. Previously I have only known it 
above the confluence of Laver, Skell and Ure. — D. W. Burch. 
1933 July * 
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