POTATO INVESTIGATIONS LABORATORY
April 8, 1958
Potato Seed Treatments and Corky Ringspot
Insecticides Used on Cabbage and Wireworm Studies
Processing Qualities of Potatoes
Irrigation and Soil Fertility Research on Potatoes
pi4 1 i
E. N. McCubbin
Varietal Studies: Ten potato varieties and 21 USDA seedling selections listed
below were planted in 12-hill plots January 16 and fertilized with 2,200 pounds of a
7-9-9 fertilizer/A. Yields as well as the desirable and undesirable tuber character-
istic of the different varieties and seedling selections will be compared at harvest.
1. 5347 10. 6003 19. B 3595-5 28. B 3692-4
2. 6077 11. 4 RM 3 20. B 3725-1 29. Pungo
3. 6509 12. Red Pontiac(Va) 21. Cherokee 30. Merrimack
4. Sebago(Ca) 13. Red Pontiac(Me) 22. B 3677-1 31. Delus
5. 6543 14. Kenrebec(Va) 23. Kennebec 32. B 3626-15
6. 3769 15. Kenuebec(Me) 24. B 2368-13 33. B 3602-4
7. 3674 16. Sebago(Va) 25. B 2368-4 34. Plymouth
8. 6515 17. Sebago(Me) 26. B 2938-22 35. Saco
9. 1859 18. Red Pontiac(Va) 27. B 929-23 36. B 355-35
Seed and Fertilizer Rates: In this test Sebago potatoes were planted January 17
at 5 different seeding rates and each seeding rate was fertilized with .8, .9, 1.0,
1.1 and 1.2 pounds of 6-8-8 fertilizer per pound of seed. Two-ounce whole seed
tubers were planted and there are 25 treatments as listed below. Yield and grades of
potatoes from the different treatments will be compared.
Lbs. of Spacing of Seed PoaCda of Fertili er per Pound of Seed
Seed/A in 40-inch Rows, -. 0" 6..- 1.1 1.2
in Inches Pounds of Fertilizeer peAcre
3,.. 13..09 1,200 1,350 1,500 I,650 1,800
2,000 9.84 1,600 1,800 2,000 2,200 2,400
2,500 7.89 2,000 2,250 2,500 2,750 3,000
3,000 6.52 2,400 2,700 3,000 3,300* 3,600*
3,50o 5,61 2,800 3,150o j 3,500o* 3,850-* ,200
*Amounts above 3,000 lbs./A applied 67 days after planting.
During the last two seasons best rate of seeding Sebago, after subtracting costs
of the seed, fertilizer, picking-up the potatoes, hauling, grading, packaging and
selling commission, has been 2,500 pounds/A. Best rate of fertilizer for this seed-
ing rate has been 1.0 to 1.1 pounds of fertilizer per pound of seed or 2,500 to
2,750 pounds of fertilizer per acre.
Herbicides for Weed Controls Three tests are being made of certain herbicides
applied pre-emergence to potatoes. In one test potato plots planted January 16 were
given the following herbicidal treatments in triplicate.
1. Vegadex(l gal.-46 gals. water/A) 2 weeks after planting.
2. Premerge(l gal..-6 gals. water/A) 2 weeks after planting.
3. Vegadex(l gal.-46 gals. water/A 3 weeks after planting.
I. Vegadex(40 Ibs. 10% Vegadex granules broadcast/A) 2 weeks after planting.
5. No treatment(check)
In another test potato plots planted February 3 were given the following herbi-
cidal treatments in quadruplicates
1. No treatment(check)
2. Premerge(l gal.-46 gals. water/A) 11 days after planting.
3. Premorge(l gal.-46 gals. water/A) 35 days after planting.
4. Premerge(l/2 gal.-46 gals. water/A) 11 days after planting.
5. Premerge(/2 gal.-46 gals. water/A) 35 days after planting.
In the third test, potato plots planted February 19 were given herbicidal treat-
ments in quadruplicate as follows:
1. No treatment(check)
2. Liquid Flame(4 gals.-55 gals. water/A) 26 days after planting.
3. Liquid Flame(2 gals.-55 gals. water/A) 26 days after planting.
4. Premerge(l gal.-5 gals. water/A) 26 days after planting.
In 1957 premerge applied at 1 gallon in 100 gala. of water/A before potato
plants grew out of the soil, gave excellent control of ragweed, rough pigweed, smart
weed, chickweed and milkweed.
Effects of Simulated Frostst In these plots potatoes were planted January 16.
Plants were Zrozsn cff at or slightly below the soil surface by low temperatures
which occurred several times until February 22. Plant emergence was delayed 2 to
3 weeks and plants were not up to stand until about March 5. Two sets of 8 single-
row plots were selected and a frost was simulated on one set of plots by burning the
plants with a blow torch March 25, 68 days after planting. The other set of plots
were left unfrosted. At harvest the yield and grade of potatoes from the two treat-
ments will be compared. In previous seasons one simulated frost soon after potatoes
came-up to stand has not reduced the yield of potatoes significantly; more than one
simulated frost, however, has caused a significant reduction in yield.
POTATO SEED TREATMENTS
A. H. Eddins
Dormant Red Pontiac and Sebago seed tubers were cut and dipped into solutions of
dormancy-breaking chemicals, antibiotics and fungicides October 14 and 15 and planted
the next day in replicated plots. Data obtained are limited to number of plants pro-
duced seven weeks after planting, as freezes in mid-December killed the plants.
Chemicals and amounts of each used in 100 gals. water to make the dipping solu-
tions are listed below.
Dormancy-Breaking Chemicals Fungicides Antibiotics
Ethylene Chlorhydrin 6.6 qts. Zineb 2.0 Ibs. Agrimycin 9.3 ozs.
Ammonium thiocyanate(NHlSCN) 6.0 Ibs. Maneb 1.5 Ibs. Agri-strep I4. ozs.
Sodium thiocyanate(NaScN) 6.4 Ibs. Phygon 1.0 lb. Phytonycin 6.4 ozs.
Potassium thiocyanate(KSCN) 7.7 Ibs. Captan 4.0 Ibs.
Formaldehyde 40% 3-1/3 pts.
Test 1.- Dormancy-breaking chemicals accelerated germination of Red Pontiac seed.
Percentage stands produced by seed treated with the different chemicals were as
follows: NH4SCN, 92.8%; KSCN, 80%; ethylene chlorhydrin, 71.2% and no treatment,
Test 2.- Red Pontiac and Sebago seed prewetted in water and soaked 30 minutes in
ioraldehyde solution before cutting and dipping in ammonium thiocyanate germinated
as rapidly and produced about the same stands as nontreated seed. Percentage
stands produced were as follows: Red Pontiac: Formaldehyde + NH~SCN', 9h%; NH4SCN,
95.3% and no treatment, 34.7%. Sebago: Formaldehyde + NH1SCN, 85.3%; NH4SCN, 90%
and no treatment, 8.0%.
Test 3.- None of the three antibiotics and four fungicides used alone and in eleven
different combinations on ammonium thiocyanate-treated, cut Sebago seed improved
plant stands. Seed pieces treated with ammonium thiocyanate alone produced a 78
percent stand and nontreated seed, 5.3%. Water supplied by rainfall and irrigation
totaled 2.31 inches during the first seven weeks after planting.
Test 1.- Cut Sebago seed pieces were treated with antibiotics and fungicides Janu-
ary7 and 8, as in the fall tests, and planted January 9 in replicated plots. One
set of plots including all treatments was irrigated with 2.41 inches water during
the first month after planting and another set was not irrigated. The irrigated
plots received 12.34 inches water and the nonirrigated, 9.93 inches during the
first 7 weeks after planting. Stands were not improved by treating the seed with
the different chemicals. Plant stand from nontreated seed in the irrigated plots
was 99.3 percent and in the nonirrigated plots, 95.3 percent.
Test 2.- Stands of plants grown from seed dipped into solutions of NH4SCN, KSCN,
-NaN, ethylene chlorhydrin and agrimycin plus zineb and planted January 15 did not
differ significantly from the 93.3 percent stand produced by nontreated seed.
Test 3.- Stands of plants produced by seed dipped into solutions of potassium gib-
berelate 0.1 ppm., potassium gibberellate 0.1 ppm. + agrinmcin + maneb, NH4SCN +
agrimycin + maneb, agrimycin + man-b and nontreated seed did not differ signifi-
cantly. Plant stand from seed dipped in NF4SCN solution was 66 percent and stand
from the nontreated seed was 95 percent. This 29 percent reduction in stand from
NH4SCN treatment in the winter tests is significant. Plants originating from
gibberellate-treated seed were about the same size as those from nontreated seed
65 days after planting.
CORKY RINGSPOT OF POTATOES
A. H. Eddins
Five replicates of 10 to 26 seed pieces each of twenty potato vari-
eties and seedling selections listed below were planted in 1958 in soil
severely infested with corky ringspot in 1957. Tubers of each variety
and selection will be examined for symptoms of the disease when the
potatoes are dug.
Free of Corky Ringspot when Free of Corky Ringspot when
growing n infested soil grown in infested soil
Variety or Years Variety or Years
Selection Tested Selection Grown
Boone 2 B 294-65 7
Delus 2 B 381-2 7
Merrimack 7 B 595-76 7
Pungo 6 B 606-3 7
Saco 3 B 3010-4 6
B 962-9 6
Susceptible Reaction Unknown
Red Pontiac Eigenheimer
Kennebec Seedling 1858
Cherokee: Tubers showed 1% corky ringspot-infection
one year; none, two years.
Plymoutht Tubers showed 7% corky ringspot-infection
one year; none, six years.
Latest information from the USDA, Beltsville, Maryland and University
of Wisconsin, Madison, is that corky ringspot is caused by a virus.
INSECTICIDES USED ON CABBAGE
E. C. Brubaker
Endrin Residue Samples... Samples for residue analysis were drawn from cabbage
treated on different dates with different quantities of Endrin in replicated plots.
The purpose of this work was to determine the amount of Endrin residue remaining
on cabbage at intervals of one to nine weeks after the insecticide was applied.
The amount of worm damage also was noted at weekly intervals following treatment
with the insecticide. Treatments and dates were as follows:
1,2 and 3
.2 lb. in spray
.2 lb. in dust
.4 lb. in spray
.2 lb. in spray
.2 lb. in spray
Nov. 8 and 22
Nov. 8 and 22
Nov. 8 and 22
Nov. 8, 14, 22 and 29
Nov. 8, 22, and Dec. 6
22, Dec. 6, 20, 27, and Jan. 3
29, Dec. 13, 27, Jan. 3 and 10
6, 20, Jan. 3, 10 and 17
22, 29, Dec. 6, 13, 20, 27, Jan. 3, 10 and 27
Five hundred and 1,000 gzam samples were taken from the plots and chopped.
Samples from replicates I and II were extracted and from III and IV were frozen.
After the last harvest all samples were sent to Dr. C.H. Van Middelem, Gainesville
for analysis. This study of Endrin residue is a part of an over-all project to
determine levels of pesticide residues on and in vegetables harvested at known
intervals following various treatments. This project is being carried out by
experiment stations and laboratories located in Gainesville, Sanford, Bradenton,
Belle Glade and Hastings.
Endrin, Parathion and Toxaphene Treatments.- A large plot testing of Endrin,
Para"thin -nd Toxaphene was initiated for studying the degree of control of cabbage
insects by these insecticides. Four-row plots 100 feet long with a three foot
break between ends of plots were used to avoid spray drift into adjacent plots.
Four replicates of each treatment were made at rates listed below.
.2 lb. actual/acre
.5 lb. actual/acre
.75 lb. actual/acre
Treatments were made on December 17 and 27, 1957, January 3 and 10, 1958.
Readings were taken for extent of insect damage to the cabbage one day previous to
each treatment and one week following the last treatment. No definite conclusions
were reached due to the lack of insect activity in all plots including the checks.
The lack of activity was apparently due to the continual cold weather experienced
throughout the duration of these tests.
POTATO WIREWORM STUDIES
E. C. Brubaker
Wireworm Populations in Soil Treated with Parathion and Aldrin.- Para-
thion and Aldrin are being tested to determine the degree of control of
the Southern Potato Wireworm. Three replicates ninety feet long each
are being used for each treatment. The replicates are divided into
30-foot plots and are treated as follows:
1 2 Ibs. actual Parathion per acre
2 4 Ibs. actual Aldrin per acre
3 Check No treatment
Soil samples were drawn and sifted to determine the wireworm popu-
lation immediately prior to treatment. The population was essentially
the same in all test plots at that time. The insecticides were applied
February 6 and the potatoes were planted and fertilized February 10, 1958.
The plots were again sampled March 17 through March 24, 1958, to deter-
mine the wireworm population. Only two live wireworms were found in
54 two-quart samples of soil drawn from the treated and nontreated
plots. Lack of wireworms is attributed to the unusually wet condition
of the soil.
The plots will again be sampled at the time of potato harvest and
the tubers will be examined to determine the extent of damage.
PROCESSING QUALITIES OF POTATOES
C. B. Hall, Main Station, Gainesville
It has been estimated that in recent years 50 to 60 percent
of the potatoes produced in the Hastings' area have been used
for chipping. Since such a large proportion has been processed,
it is desirable that information be obtained to determine the
conditions under which the highest quality potatoes for processing
can be produced. Information which would help the potato industry
to supply a higher quality raw product should create a greater
demand for processing potatoes from Florida.
Factors listed below which may affect the processing qual-
ities of potatoes are being investigated at the Main Station,
Gainesville, in cooperation with the Potato Investigations
1. Influence of maturity
2. Influence of the sulfate versus chloride
form of potash
3. Influence of soil moisture
U. Varietal differences
IRRIGATION AND SOIL FERTILITY RESEARCH ON POTATOES
D. L. Myhre
1. WATER-FURROW IRRIGATION.- An irrigation and fertilization experiment is being
continued for the fourth consecutive year in the same area which had been level-
ed in 1954. The soil is predominantly Bladen loamy fine sand. This experiment
includes three varieties (Sebago, Red Pontiac and White Rose), four soil moist-
ure levels and four fertilizer treatments. Soil moisture tension, soil moisture
content and water table levels are being determined in the plots. Yield and
quality of the potatoes will be determined at digging time.
Water has not been turned on in the irrigation furrows since planting on
January 23 because excessive rains resulted in a high water table and an above
optimum moisture content of the topsoil. Similar water-logged conditions were
encountered in the Hastings area in heavier soils which contained sufficient
clay to reduce the permeability and in soils where the clay subsoil is less than
two feet from the surface.
Fertilization Treatments (2,200 Ibs./A of 7-9-9):
A = All fertilizer broadcast before planting.
B = broadcast before planting and in bands at planting.
C = broadcast before planting and 3/4 in bands at planting.
D = All in bands at planting.
Soil Moisture Levels:
1 Very high; rows 1-4 from irrigation furrow.
2 = High; rows 5-8 from irrigation furrow.
3 = Medium; rows 9-12 from irrigation furrow.
4 = Low; rows 13-16 from irrigation furrow.
2. FERTILIZATION OF POTATOES.-
a. Sidedressing Test.- Sebago potatoes were planted January 17 in Leon fine
sandy soil and fertilized with 2,200 Ibs./A of 7-9-9 applied in 2 bands. The
plants were sidedressed with 30 Ibs./A of nitrogen on March 14 using seven
different fertilizer materials. Yields will be determined at digging time.
Fertilizer Percent L Lbs. Required to
Treatment Nitrogen Give 30 Lbs. Nitrogen
1 = 6-8-8 (all soluble) 6 500
S2 = 7-9-9 7 429
3 = 10-0-10 (all soluble) 10 300
4 = Ammonium Nitrate 33.5 90
5 = Nitrate of Soda-Potash 15 200
S6 = Urea 45 67
7 = Nitrate of Soda 16 188
8 = None 0 0 i
A similar test in 1957 showed that fertilizer sidedressings reduced potato
yields where whole, 1 3/4 ounce seed were planted and increased potato yields
where whole, 3 ounce seed were planted. However, ammonium nitrate was the only
sidedressing material which gave a significant increase (1% level) in yield.
b. Foliar Nutritional Sprays.- Yields of Sebago potatoes will be determined
in plots consisting of the following treatments:
1 = 2,200 lbs./A of 7-9-9 fertilizer.
2 = Treatment "1" + 5 weekly applications of 2 gal./A of 10-20-10.
3 = 1,500 Ibs./A of 7-9-9 fertilizer.
4 = Treatment "3" + 5 weekly applications of 3 gal./A of 10-20-10.
No significant differences in potato yields were obtained due to foliar
sprays in 1955, 1956 or 1957 where the initial fertilizer application was
equivalent to more than 2,000 lbs./A of 6-8-8.
c. Chloride-Sulfate Experiment.- Tests begun in 1954 by Dr. G. M. Volk
are being continued for the fifth successive year to determine the influence of
muriate and sulfate sources of potash and date of digging on yield and quality
of Sebago and Red Pontiac potatoes. The plots were fertilized with 2,500 Ibs./A
of 6-8-8 fertilizer containing either muriate or sulfate of potash and planted
January 16. All plots were sidedressed with 200 lbs./A of nitrate of soda-
potash on March 17. Yield and quality of potatoes will be determined at 90,
100 and 120 days after planting.
In 1957 Sebago and Red Pontiac potato yields were increased an average of
15 and 10 percent, respectively, by using fertilizer which derived its potassium
from sulfate of potash rather than muriate of potash. A similar trend was ob-
tained in 1955. However, no apparent significant yield differences occurred in
1954 or 1956.
d. Potassium Gibberellate (Plant Growth Regulator).- Tests are set up to
study the effects of dipping whole and cut potato seedpieces in 0, .1, .5, 1, 5
and 10 p.p.m. of potassium gibberellate solution on growth, quality and yield
of Sebago potatoes.
Tests in 1957 showed that concentrations of less than 1 p.p.m. produced
normal tubers while concentrations of more than 10 p.p.m. produced elongated and
pear shaped tubers. Also, potato yields were increased significantly by dipping
whole Sebago seed in .1 p.p.m. of gibberellic acid.
3. IMPROVING OLD LAND FOR POTATO PRODUCTION.-
a. Cover Crops.- An experiment was set up in 1956 and continued in 1957 and
1958 to determine the residual effects of different summer cover crops on soil
improvement and potato yields. Plots were planted to the same cover crops on
May 28, 1956 and April 29, 1957 and to potatoes on January 22, 1957 and
January 30, 1958.
Yields of potatoes in 1957 following the 1956 summer cover crops of corn,
cattail millet, regular hegari, corn and velvet beans, volunteer crabgrass,
Egyptian wheat, Texas ribbon cane and sesbania were 208, 202, 202, 201, 190,
189, 180 and 148 hundred-pounds per acre, respectively.
b. Potato-Pangolagrass Rotation.- A potato-pangolagrass rotation experiment
was set up on Bladen loamy fine sand in September 1954 and will terminate at the
end of the 1958 potato season. The purpose of this study was to determine the
effects of one, two and three years of pangolagrass on soil physical changes,
potato yields and incidence of corky ringspot.
Sebago potato yields were increased 23% in 1956 as a result of one year
of pangolagrass preceding the potato crop and 10% in 1957.
c. Land Leveling and Deep Plowing.- Sebago and Red Pontiac potato yields
will be determined in a leveled (1955), a deep plowed (1956) and an undisturbed
area. The organic hardpan in the "Leon" areas was broken up with a dozer blade
and mixed with the topsoil prior to leveling.
Potato yields in 1957 were highest in the area which was plowed to a
depth of 15 inches.
4. SPECIFIC GRAVITY OF POTATO TUBERS.- Specific gravity measurements will be made
on potatoes grown for some of the above experiments and other tests in order to
determine the influence of various soil and cultural factors on specific gravity
of potatoes and develop methods for improving this important quality of potatoes.
Results in 1957 showed that specific gravity increased with maturity and
higher specific gravity tubers were grown by using sulfate as the source of
potash in the fertilizer.