EVERGLAIES EXPERIMENT ST!'TION
*Mimeograph Report No
Mimeograph Report No, 20
POTATO, Solanum tuberosum
VARIETY AM SEEDLING TEST
James C. Hoffman
POTATO VARIETY A~T SEEDLING TEST
James C. Hoffman
A test of 11 potato seed stocks were planted October 21, 1948,
and harvested January 26, 1949. Each variety or seedling was planted in
five randomized blocks. The replicates of each block were 20 feet in
The seed pieces averaged 1 ounce in weight. Since some of the
seedlings are classified as scab resistant, the formaldehyde treatment
as described in Farmers' Bulletin No. 1881, Page 51, was not used. After
being hand cut the seed pieces were treated pith ammonium thiocyanate at
a concentration of 3 pounds in 50 gallons of water. The seed pieces were
dipped in this solution the late afternoon of October 20, before being
planted the next morning.
All rows were spaced 36 inches apart, and the sead pieces were
planted 12 inches part in the drill. The seed pieces were covered at an
approximate depth of 3 inches,
The plots were located on well mature sawgrass peat with a
pH averaging 5.60. There was a residual level of 3 pounds of phosphorus
and 40 pounds of potassium per acre. To this area fertilizer was ap-
plied at the time of planting at the rate of 600 pounds of 0-8-24, 60
pounds manganese sulphate, 30 pounds copper sulphate, 24 pounds zinc
sulphate and 12 pounds of borax per acre, in two bands 4 inches on each
side of the seedbed and 3 inches in depth.
The potatoes were sprayed with Dithane D-14, at a concentration
of 2 quarts of Dithane, 1 pound of zinc sulphate in 100 gallons of water,
and applied at the rate of 125 gallons per acre. A total of seven appli-
cations were applied, each at weekly intervals starting on the 15th day af-
ter planting. Late blight Phytophthora infestans (Mont.) De Bary was only
partly controlled. After the fifth spraying blight developed very rapid-
ly on the non-resistant stocks.
Tuber development and final yields appeared to be greatly vit-
iated by high temperatures. The temperature for the growing season.averaged
7527 F. for the period from 6:00 A.M. to 6:00 P.M., and 63.80F. for the
period from 6:00 P.M. to 6:00 A.M. or a general average temperature of
69.80F. for the potato growing season. The average low and high temperatures
for the potato growing season was 57.80F. and 83.hF. respectively. The
water table averaged approximately 30 inches during the growing season.
The data as presented in Table 1 with the exception of column
5, are from a perfect stand of 10 hills taken at random and harvested from
each replication. The yield data presented in column 5 was taken from a
second replicated planting of three rows, each row, 200 feet in length.
A description of each numbered column is outlined as follows:
Table 1. (1) The Maine potatoes were supplied by Dr. F. J.
Stevenson of the United States Department of Agriculture; Maryland potatoes
by Dr. R. A. Jehle and thj North Dakota potatoes by Walter Peterson.
(2) The data as listed is the per cent of total number of
potatoes having scab.
(3) The late blight ratings are listed as a relative scale:
1. No blight.
3. Slightly susceptible.
5. Seriously damaged.
(4) Calculated yield in bushels of marketable potatoes per acre
from 50 hills taken from the five replications.
(5) Calculated yield in bushels of marketable potatoes per acre
from 600 linear feet of row taken from the three replications.
The potato seed stocks sent from iaine were extremely green and
there is a possibility that the dormant treatment was not adequate with
the possible exception of B76-43. The sprouts on these potatoes appeared
generally weak, no doubt, being associated with the dormant condition or
extreme high temperatures at planting time. This is the first of a series
of four tests that Kennebec has not been in the high yielding brackets
with the highest yielding stocks.
There is a significant difference between western and eastern
grown Pontiac seed stocks. The factors responsible for these yield var-
iations are beyond discussion as the history of the seed stocks is unknown.
It can be concluded from this test, and has been commonly observ-
ed. in other tests, that the grower must consider very strongly where his
seed stocks are produced and how they are stored and handled. Kennebec,
a new blight resistant white potato should be of interest to the potato
growers of the Everglades area. This variety has shown exceptionally good
quality and is usually a high yielding stock. The low yield of Femaebee
in this test is not in agreement with its performance in praeictestesa
Seedling B76-43 has been consistently a high yielder, however,
it has shown some roughness ard growth cracks if given the same length
of growing season as Pontiac or Triumph. This seedling should again be
tested in the Everglades area, and given a 75 day growing season. If B76-
43, a late blight resistant seedling can be grown as a short season potato,
without roughness or growth cracks, it should be of interest' to the potato
growers of the Everglades.
TABLE NO. I.
POTATO VARIETY AND SEEDLING TEST, EVERGLADES EXPERIMENT
STATION, BELLE GLADE, FLORIDA
Field Variety or Seed Late Mean Yield
No. Seedling Source Scab Blight Bu. per acre
(1) (2) (3) (l) (5)
Least significant difference at the 5 Per Cent Point 66 32
Least significant difference at the I Per Cent Point 89 8