MARCH 30, 1967
'I tI i
IN COOPERATION WITH FLORIDA
AGRICULTURAL EXTENSION SERVICE
POTATO INVESTIGATIONS LABORATORY
NINETEENTH ANNUAL FIELD DAY PROGRAM
March 30, 1967
Paul Dinkins, St. Johns County Agent, Presiding
Introduction, Paul Dinkins
Cabbage Harvester & Fertilizer Studies
Dr. D. R. Hensel, Associate Soils Chemist & Head 1
Insect Control Tests and Weed Control Tests
Dr. R. B. Workman, Assistant Entomologist 4
Diseases & Controls, Variety Trials, and Potato Defoliants
Dr. R. M. Hosford, Jr., Assistant Plant Pathologist 6
Following a coffee break, a tour of the
experimental plots will be conducted.
CABBAGE HARVESTER & FERTILIZER STUDIES
D. R. Hensel
CABBAGE HARVESTER STUDIES: This is the second year of a lengthy testing program
which is designed to develop a cabbage harvester. A prototype machine was used
at three locations in Florida last year. Some of the limitations of the harves-
ter are under detailed study this year.
Both mechanical harvesting and hybrid type cabbage will completely dominate
cabbage farming within the next ten years. Labor shortages and costs are forcing
the trend to mechanization. It appears that the only reasonable type harvester
at this time is one that will harvest the entire crop at one time. Hybrid vari-
eties appear to be the most promising. Last years results indicate, however,
that both the harvester and the hybrid varieties need to be improved.
This year three experiments are under study at this Potato Investigations
Laboratory. The tests were as follows:
Varieties: Market Topper, King Cole, and Marion Market.
Seed Size: Small, medium, large, and unsized.
Variables measured: Emergence, plant stand, and plant size.
When analyses are completed the data should indicate which seed size and
variety will give the most uniform plants and what factors should be used
in selecting transplantable plants.
Varieties: Market Topper, King Cole, and Marion Market.
Seed Size: Medium size seed only for this test.
Spacing: 12 inches only.
Plant Sizes: Small, medium, large, and random (unsized).
Planting depth: Random, deep, and shallow set.
Variables measured: Head alignment, bare stem length, leaf stem length,
head diameter, head weight, and grade.
Results of this test will indicate what factors need consideration in
order to produce uniform sized heads which have nearly the same stem
length and mature at the same time.
Varieties: Market Topper and King Cole.
Seed Size: Medium.
Plant Size: Medium.
Variables: Machine cut and hand cut methods.
This test will provide us with information on the performance of the
prototype machine under field conditions. Results will indicate whether
or not the machine is acceptable and what are its major limitations.
Modifications will be made to correct deficiencies in the harvester.
- 1 -
LIQUID FERTILIZER TESTS:
Cabbage: Last year, various combinations of liquid and solid fertilizer
mixes were applied to the soil in cabbage plots. Yields in both cases
were very good and little or no differences due to form of the fertili-
zer could be found. This year, combinations of liquid fertilizer place-
ment are being compared to recommended solid fertilizer placements. Re-
sults should provide an indication whether the best placement of liquid
fertilizer differs significantly from best method of solid placement.
Potatoes: Results of last year indicated that when rates of fertilizer appli-
cation were equivalent to 3000 pounds/A of 6-8-8, differences between
solid or liquid fertilizer were not significant. When 2000 pounds of
fertilizer or less were used, the solid materials produced greater yields.
Since 7 inches of rain fell during the month of February, these results
could be expected.
Split application of the 2000 pounds of liquid fertilizer rate did not
produce potato yields equal to that of the single application. Results
are shown in the following table:
Yield of Sebago Potatoes in 1966
Lbs 6-8-8 1000 2000 3000
Solid 149 268 278
Liquid 111 216 270
This year the experiment is being repeated. In place of the split appli-
cation treatment, a 12-16-16 clay suspension application was included.
Experiment is in progress at this time.
Also, in 1966 combinations of various liquid potassium sources were com-
pared with solid fertilizer. Yield differences between solid and liquid
were not significant. The largest potato yield (252 cwt/A) was obtained
when sulfate of potash was applied in the liquid form.
A high analysis 14-16-16 solid fertilizer was applied at the rate of
1250 pounds per acre.
1. Check no micro nutrients added.
2. 50 pounds/A Fertminal.
3. 100 pounds/A Fertminal.
4. Boron only equivalent to 100 pounds Fertminal.
5. 14-0-16 no micro nutrients.
6. 14-0-16 plus 100 pounds Fertminal.
7. Commercial 7-8-8 1.5% organic nitrogen 2500 pounds/A -
no micro nutrients.
8. Liquid fertilizer All phosphorus in 10-34-0 poly phosphate
This experiment was placed on both old and new land.
All treatments received 150 pounds of nitrogen in addition to 100 pounds
per acre Fertminal.
0 100 200
100 100 1 200
200 100 200
SUBSOILING & HARDPAN STUDIES: Potato experiments are being conducted at three
locations to determine the effects of deep and shallow chiseling of the subsoil.
Results of these tests will be used to determine what effect the subsoil and hard-
pan has on "potato decline" problems on old land.
Plans are being made to include in this study next year several variables.
Type of cover crop, nitrogen fertilization, age of cover crop when plowed down,
depth of chiseling, and location on new and old land are the variables. Data
on physical measurements of soil structure and effect of treatments on yields
will be taken.
WEED CONTROL TESTS
CABBAGE: Dacthal, Eptam, and Treflan were sprayed on the soil and disced in be-
fore planting. Randox plus Vegedex and Tok were sprayed on after planting.
Percent control (Fall weeds)
Herbicide A/A (ibs.) Chickweed Dock Lactuca
Dacthal 75W 4.5 95.6 93.7 72.9
Eptam 6E* 3.0 74.6 63.0 73.9
Randox 4E and Vegedex 4E 4.0 each 90.9 95.1 87.1
Tok 2E 3.0 78.5 100.0 93.9
Treflan 4E 2.0 88.2 --- 87.3
POTATOES: Dacthal and Eptam were disced into the soil before planting.
Premerge and Randox plus Vegedex were applied after planting. No weed counts
have been made to date.
Randox 4E & Vegedex 4E
Herbicides recommended for use in
INSECT CONTROL TESTS
CABBAGE LOOPER CONTROL-- Eight weekly applications: 100 gals/A., 300 psi, 6
nozzles/row. Four replicates, 25 plants rated per plot. Plants rated 1-5:
1 = 0-1%, 2 = 2-5%, 3 = 6-10%, 4 = 11-30%, and 5 = 304 worm injury (holes).
A/A (oz. )
Dupont 1179 95W
Niagara 10242 50W
Gen. Chem. 6506 4E
Chevron RE 9006 6E
Niagara 10242 50W
Parathion 4E + Toxaphene 8E
Geigy 13005 3.67E
Guthion 2E + DDT 2E
Geigy 10128 50W
Rating (Ner plant average)
CABBAGE APHID CONTROL-- Eight weekly applications: 100 gals/A., 300 psi, 6
nozzles/row. Four replicates, 10 plants per plot. Aphid numbers rated 1-7:
1 = 0, 2 = 1-2, 3 = 3-10, 4 = 11-25, 5 = 26-50, 6 = 51-100, 7 = 100+ aphids
on the bud leaves of the plant.
Rating (per plant average)
No. Treatment A/A (oz.) Brussels sprouts Rutabaga
1. Meta-Systox-R 2E 6 1.85 2.05
2. Di-Syston 6E 6 2.18 1.80
3. Azodrin 3.2E 8 2.60 2.83
4. Niagara 10242 50W 8 2.63 2.58
5. Bidrin 9E 12 2.85 2.35
6. Azodrin 3.2E 6 3.08 2.05
7. Diazinon AQ500 8 3.18 2.25
8. Niagara 10242 50W 16 3.35 2.28
9. Geigy 13005 3.67E 16 4.10 2.90
10. Parathion 4E + Toxaphene 8E 8+32 4.13 3.28
11. Parathion 4E 8 4.40 3.35
12. Wepsyn 10%E 4 4.58 5.60
13. Gen. Chem. 6506 4E 8 4.60 3.43
14. DuPont 1179 95W 8 5.10 4.03
15. Guthion 2E + DDT 2E 8+8 5.38 4.78
16. Chevron RE 9006 6E 8 5.63 3.43
17. Geigy 10128 50W 16 6.75 6.83
18. Check--Maneb 7.00 7.00
DISEASES & CONTROLS, VARIETY TRIALS,
& POTATO DEFOLIANTS
Robert M. Hosford, Jr.
CABBAGE BLACK LEG, caused by the fungus Phoma lingam, has not been seen in the
Hastings area for many years. The control for this disease has been hot water
treatment of the cabbage seed. Recently Drs. J. C. Walker and Paul Williams said
that what seems to be a hot water resistant strain of the fungus has appeared in
the United States. The disease is characterized by a dry rot and blackening of
the lower part of the stem and roots. Any appearance of this disease in the
Hastings area should be reported to the Potato Investigations Laboratory for con-
firmation and forwarding of the information to the seed supplier.
CABBAGE DOWNY MILDEW causes spotting of the cabbage head as it nears maturity.
This spotting disfigures the head and when severe makes the head unmarketable.
During the 1966-1967 cabbage season six foliar fungicide spray treatments are
being compared for effectiveness in controlling the disease on maturing cabbage.
Each treatment is being applied to four plots (each 50 feet by four rows) located
in a randomized block pattern in two beds of cabbage. Spraying is being done at
a rate of 100 gallong/acre, using a four row commercial sprayer with 6 nozzles per
row and operating at 300 psi.
The treatments are:
Dithane M22 (80W) at 1.5 lb + Triton B1956 at 6 oz/100 gal/A.
Dithane M45 (80W) at 1.5 Ib + Triton B1956 at 6 oz/100 gal/A.
Manzate D (80W) at 1.5 Ib + Dupont Spray Sticker at 6 oz/100 gal/A.
Polyram (80W) at 1.5 lb /100 gal/A.
Fermate (76% Ferbam) at 4.0 lb/100 gal/A.
Fermate at 2.0 lb + Terraclor at 2 lb/100 gal/A.
Check No Treatment.
Comments: By 3/9/67 many heads were ready for harvest, but only a slight amount
of mildew spotting had appeared in any of the plots. Spraying was continued,
and disease ratings are being made as the spotting increases on the mature cabbage.
While Fermate and Terraclor are being rated for control of mildew, they are prin-
cipally being studied as a chemical control for Sclerotiniose.
- 6 -
CABBAGE DOWNY MILDEW, caused by the fungus Peronospora parasitica,severely stunt-
ed or killed high percentages of unprotected seedlings in the Hastings area during
the 1966-1967 cabbage season. Nine foliage spray treatments were compared for
effectiveness in controlling the disease. Each treatment was applied a total of
ten times at 2 to 3 day intervals to three 25-foot-by-4-row plots located in a
randomized block pattern in a cabbage seed bed. Spraying was begun on emergence
at a rate of 100 gallons/acre and increased to 150 gallons/acre as the seedlings
grew bigger. The sprayer was a four row commercial sprayer with 6 nozzles per row
and was operated at 300 psi. Disease control was estimated by (1) counting the
number of young seedlings with mildew on their cotyledons and first true leaves in
two sections of 50 consecutive seedlings in each plot and (2) weighing the seed-
lings in 5 foot sections in each plot when the seedlings in most plots were large
enough to transplant.
Table 1. Comparison of chemicals for their effectiveness in controlling downy
mildew in the cabbage seed bed at Hastings, Florida in 1966._ __
Treatment Concentration Mildew Averaged
(in 100 gallons) _.Rating* ___ weight**
Spergon (48W) + 3 lb. 1.13 a 328.3 grams
Dithane M22 (80W) 1.5 lb.
Spergon (48W) 4 lb. 1.27 a 514.3
Dithane M22 (80W) 2 lb. @ 1.70 ab 319.0
Dithane M45 (80W) 2 lb. @ 2.28 ab 415.0
Manzate D (80W) 2 lb. @@ 2.48 b 337.0
Polyram (80W) 2 lb. 3.55 c 299.7
Daconil 2787 (75W) 1.5 lb. 4.08 cd 286.0
Dithane Z78 (75W) 2 lb. 4.20 cd 287.7
Triton B 1956 10 ounces 5.00 d 154.3
Check 5.00 d 151.0
* Rating system: 0 = Of of seedlings infected, 1 =20% infected, 2 = 40%, 3 = 60%,
4 = 80%, 5 = 100% and no control. Treatment F Value = 19.0, Required F Value
at 5% level = 2.46, at 1% level = 2.9. LSD at 5% level = 7.9, at 1% level =
** Treatment F Value = 4.36, Required F Value at 5% level = 2.46, at 1% level =
@ Plus 6 ounces of Triton B 1956.
@@ Plus 6 ounces of Dupont Spray Sticker.
a-d Significantly different control at the 5% level of probability as estimated
by the Duncan Range Test.
Discussion: Spergon (chloranil) or maneb type formulations gave a better control
of downy mildew than the other treatments, and gave enough protection to enable
the seedlings to grow beyond the young extremely susceptible stage. While this
protection is adequate, it is not complete and must be applied 2 to 3 times a week.
A more effective and less laborious control is being sought.
CABBAGE BLACK ROT, caused by the bacterium Xanthomonas campestris,was severe and wide
spread in the Hastings area during the 1964-1965 cabbage season. Hot water treatment
of the seed, placing of seed beds on land not previously in cabbage, and sanitary
practices were strongly recommended to the Hastings growers and to Georgia growers
that supply seedlings to the Hastings area.
During the 1965-1966 season the disease occurrence suggested that some of the
seedlings coming from Georgia might be infected. A Georgia Inspector examined some
suspected Georgia seed beds but found no black rot.
During the 1966-1967 season the disease has appeared in one Hastings seed bed
and seven fields of transplants. The cabbage in severely infected areas in two of
these fields were plowed under. Circumstantial evidence suggested that the black
rot in four of these fields might have arrived on infected seedlings from Georgia,
but this has not been proven. The black rot in the Hastings seed bed and the three
fields transplanted from it was investigated in an attempt to determine if the seed
might be the source of the disease. The seed used in planting the seed bed had been
grown in California and Washington and hot water treated in Hastings. The seed bed
was placed on land that had not previously been in cabbage. Following discovery of
the black rot, seed from the same lots were 1 hot water treated at the Potato
Investigations Laboratory, 2- hot water treated by a commercial company in Hastings,
or 3- left untreated. Portions of these seed were planted in replicated field plots
and portions were sent to Dr. Paul Williams at the University of Wisconsin for green-
house testing. No black rot was found in any of the plants grown from these seed,
either here or at Wisconsin. This suggested that the bacterium was not in or on the
seed. The bacterium may have been 1- on infested containers or equipment into which
the seed was placed after hot water treatment, 2- in wild or cultivated plants related
to cabbage, 3- in refuse of previous crops, or 4- in the soil itself. Careful sani-
tary practices should be followed to minimize the danger of infection from as many of
these sources as possible. Hot water treatment of the seed and placing of the seed
bed on land not previously in cabbage should be continued here and in Georgia.
DAMPING OFF OF CABBAGE SEEDLINGS, caused by several soil-inhabiting fungi, killed
high percentages of cabbage seedlings in some seed beds around Hastings during the
1966-1967 cabbage season. In cooperation with Dr. R. B. Workman, a drench of 2
pounds of Captan 50W and 2 pounds of Terraclor 75W per acre was applied to three
alternating 270 foot rows of emerging cabbage seedlings in a cabbage seed bed. The
bed was located on land that had been in grass the previous year. The seed bed was
periodically examined for damping off. Only a very few seedlings in the bed damped
off, and there was no noticeable difference in damping off between drenched and un-
drenched rows. Since fungi that cause damping off of cabbage seedlings are likely to
increase in soils planted year after year to cabbage, the low incidence of damping off
might have been attributable to the locating of the seed bed on land that had been in
grass. This land probably contained a relatively small number of damping off fungi.
Annual rotation of the seed bed to land that has not been in cabbage the prior year
is a standard recommendation that should be followed.
CABBAGE WATERfROT, caused by the fungus Sclerotinia sclerotiorum, destroyed high
percentages of maturing plants in some growers fields during the 1965-1966 cabbage
season. During this 1966-1967 season Fermate (76% ferbam) at 4 pounds/100 gallons/
acre and Fermate at 2 pounds plus Terraclor 75W at 2 pounds /100 gallons/ acre are
being applied as weekly sprays to maturing cabbage as a experiment on the control of
wateryrot. So far this season watery rot has not caused anywhere near as much damage
as last season. It is not present in enough sprayed and unsprayed plants to rate the
chemicals for effectiveness in controlling it. The disease is favored by prolonged
cool, r~lny weather. However, disease may develop during warm weather. On 3/15/67 a
serious infection was observed in a 30 acre field one mile from the Laboratory. It
appeared that spores had infected freeze damaged mid ribs of wrapper leaves, and the
fungus was spreading to the heads.
- 8 -
POTATO LATE & EARLY BLIGHTS, caused respectively by the fungus Phytophthora infestans
and the fungus Alternaria solani, often damage the potato plants growing in the
Hastings area. Early blight usually appears too late in the season to seriously
affect yield. During the 1965 -1966 potato season eleven foliage spray treatments
were compared for effectiveness in controlling these diseases. Each treatment was
applied a total of ten times at weekly intervals to four 50-foot-by-4-row plots
placed in a randomized block pattern in a potato field. The treatments were applied
with a four row sprayer, equipped with 6 nozzles per row, at a rate of 100 gallons
per acre and 300 psi. Applications were begun when the plants were 4 to 6 inches
tall on March 11 and ended on May 11, 1966. No late blight appeared in any of the
plots. Late in the season, as the potatoes neared maturity, severe early blight
appeared in the check plots. On May 13-15 early blight control was estimated by
rating the number of target shaped lesions on the foliage of 20 potato stems, each
with numerous leaves, in the center two rows, ten feet in from the ends, in each
plot. The rating for each treatment was determined by obtaining the weighted sample
means of the lesion ratings.
Table 1. Rating of fungicides for control of potato early blight at Hastings,
Florida in 1966.
Treatment lbs./acre -Rating*
Du-ter 50W 0.75 1.13@
Du-ter 50W 0.50 1.20@
Daconil 2787 75W 2.00 1.29
Daconil 2787 75W 1.50 1.45
Daconil 2787 75W 1.00 1.49
Manzate D 80W 1.50 1.60
Dithane M22 80W 1.50 1.64
Polyram 80W 1.50 1.90
Difolatan 80W 1.50 2.01
Dithane M45 80W 1.50 2.20
Miller Fungicide 658 90W 1.50 2.88
Check No treatment -0- 5.68
Check No treatment -0- 6.00
* Rating: 1. = 0 lesions/stem, 2. = 1-5/stem, 3. = 6-20/stem, -. = 21-40/stem, 5. =
41-80/stem, 6. = 81-oo/stem (oo = leaves completely killed by numerous lesions)
Treatment F value = 82.2, Required F value at 5% level = 2.04, at 1% level = 2.73.
LSD at 5% level = 0.30, at 1% level = 0.40.
@ Numerous small brown spots appeared on the undersides of the leaves suggesting
In addition to the above, starting on April 26 the fungicides (with some rates
omitted) were sprayed as above, 3 times, at weekly intervals on late March 3rd plant-
ed Sebago potatoes. These potatoes were still vigorously growing on May 13-15, when
early blight was observed in the above potatoes planted on January 19. Only a trace
of early blight was found in the late planted potatoes on May 13 or thereafter. Du-
ter did not cause any significant phytotoxicity in the late planted potatoes.
Discussion: Du-ter and Daconil 2787 appear to give the best control of early blight
of potatoes. Du-ter may cause some phytotoxicity. All treatments give a significant-
]y better control of early blight than the checks. This season (1966-1967) the Du-
ter formulation will be compared to a new formulation containing a new combination of
safening ingredients. Daconil 2787 will be tested at five different concentrations
in an attempt to determine the most desirable dosage. Manzate D, Dithane M22,
Polyram, Difolatan, and Dithane M45 will be tested at the same concentrations.as
POTATO SEED PIECE DECAY AND BACTERIAL BLACK LEG severely u;
from January to late February in the 1965-1966 Hastings potato season. Decay,
caused principally by species of the fungus Fusarium and strains of the bacterium
1: 'r a carotovora, and black leg, caused by the strains of E. carotovora, were
favored by freezes and heavy rains in January and February. In New York and North
Dakota seed piece treatments have been effective in controlling decay and black
leg during adverse weather. On March 3, 1966, potato variety Sebago seed pieces
were cut and (1) dusted with 1 pound of 7% Polyram dust/100 pounds of seed pieces,
(2) dusted with r pound of 15% Captan dust/100 pounds, or (3) not dusted. That
same day all the seed pieces were planted in replicated field plots. Emergence
was 80-100%. Yields were good, around 200 cwt/A, and practically no disease
appeared. There was no noticeable difference in emergence counts, yield, or
specific gravity of dusted or not dusted potatoes. Other potatoes planted in
March were also quite free of decay and black leg. After Febrian.ry weather con-
ditions did not favor seed piece decay or black leg.
During the 1966-1967 potato season, on January 23, 1967 and February 17, 1967,
seed pieces were cut and (1) dusted with 1 pound of 7% Polyram dust/100 pounds of
seed pieces, (2) dusted with 1 pound of 15% Captan dust/100 pounds, (3) dusted
with L pound of 15% Difolatan dust/100 pounds, (4) dusted with 1 pound of 75W
Daconil 2787/100 pounds, or (5) not dusted. That same day all the seed pieces
were planted in replicated field plots. 20 seed pieces from each treatment were
placed in each of 5 twenty-foot sections of row (plots) arranged in a randomized
block pattern. On February 26, 1967 the emerging plants were frozen back to the
ground level. By March 13, 1967, 50 to 100% reemergence had occurred, and plants
were still emerging. The potatoes in each treatment will be compared for percent
emergence, yield, and specific gravity.
DISEASE ON SEED POTATOES: This season Fusarium seed piece decay and soft rot were
observed destroying varying numbers of seed potatoes. Phytophthora infestans, the
cause of late blight of potatoes, was consistently isolated from a low percentage
of potatoes in a shipment of Certified Canadian Sebago seed potatoes. Better in-
spection at the shipping point and more careful handling at harvest, in transit,
and in storage should re4ucl losses from these diseases.
- 10 -
CABBAGE VARIETY TRIALS: Cabbage varieties are being tested for their adaptability
to the Hastings area. Measurements are being taken to determine percent yield at
first harvest, total yield, time required for maturation, shape, uniformity as to
shape and size, core length and diameter, head density, cold tolerance, mildew
resistance, and color. Each of 24 selections was transplanted into 5 twenty-five
foot sections of row randomized in blocks. Each section (plot) contained between
25 to 30 heads of cabbage. Each of 16 selections was placed in a single row
observational plot of variable length. No fungicide was applied between trans-
planting and harvesting.
In randomized nlo~ts
1. Market Topper
2. Market Prize
3. Harris Resistant Danish
4. Resistant Danish W5 (W75)
5. Hybrid D
7. Inbred E 18/22
8. Suprette Hybrid (F.M. E202)
9. Little Rock Hybrid (F.M. 9)
10. Greenback Y.R.
11. Roundup Hybrid (F.M. 5)
12. Marion Market
13. King Cole Y.R.
16. 77F S.C.
21. T. Sakata Hybr
28. T. Sakata Savo
39. Klean Cut
40. Rio Verde
In single observational plots
Selection Source Selection Source
6. Hybrid G H. 31. Hoffman 16-3 Hal.
15. 77F PCB B. 32. Hoffman 16-4 Hal.
18. Round Dutch set 89. B. 33. Hoffman 17-1&4 Hal.
19. Globelle K. 34. Hoffman 17-1 or 4 Hal.
20. Globe 62M K. 35. Hoffman 17-2 Hal.
22. T. Sakata Hybrid No. 19 Hal. 36. Hoffman 17-3 Hal.
29. Hoffman 16-1 Hal. 37. Hoffman 17-5 Hal.
30. Hoffman 16-2 Hal. 41. Hybrid 901 N.K.
H. is Dr. R. 0. Wilkins, Plant Breeder, J. Harris Seed Co.
F.M. is Ferry Morse Seed Co.
B. is Dr. W. C. Barnes, Superintendent, Clemson University Agricultural Exp. Station,
Truck Station, Charleston, South Carolina.
Hal. is Professor L. H. Halsey, University of Florida, Gainesville, Florida
N.K. is Northrup King Seed Co.
K. is Keystone Vegetable Seed Co.
T. Sakata is a breeder in Japan, and Hoffman is Dr. Jack Hoffman of the U.S.D.A.
Comments: All the plants, except those from Northrup King were raised from seed.
In the seed bed selections 28, 29, 32, and 33-37 had noticeable less mildew on their
cotyledons and primary leaves than the other selections. Mildew was severe through-
out the Hastings area, and all the seedlings in this study were sprayed two to three
times a week with fungicide.
- 11 -
POTATO VARIETY TRIALS: The current testing program includes 17 selections. There
are 9 named varieties and 8 seedlings. Each selection is planted in 5 plots, ran-
domized in blocks with three foot gaps between plots. Each plot is a ten foot
section of row containing 10 seed pieces. Sebago is the standard recommended
variety in the Hastings area for white potatoes. Red LaSoda is the standard re-
commended red potato. Pungo is resistant to corky ringspot and is recommended
for fields infected with the disease. The freeze of February 26, 1967, caused
some damage to the potatoes and killed their tops. However, in emergence counts on
March 12, 1967, all plots had 90 to 100% stands. Each variety will be examined
for stand count, yield, specific gravity, appearance, and if possible chipping
Brand varieties and seedlings under test this year are:
1. 6HS-9 Kennebec x Pennchip 10. B5066-3 Strain No. 64
2. 6CX-6 Kennebec x Merrimac 11. LaChipper Strain No. 1686
3. 6IE-1 4SL-2 x Katahdin 12. Pungo Strain No. 1703
4. B5141-6 Strain No. 68 13. Reliance Strain No. 1727
5. Huron Strain No. 1677 14. Penobscot Strain No. 1700
6. Red LaSoda Strain No. 2152 15. 6127-10R (red)
7. B5063-3 Strain No. 11 16. 58991 (white)
8. Ona Strain No. 2695 17. Sebago
9. Catoosa Strain No. 2657
POTATO DEFOLIANTS: On :May 3, 1966, potato foliage in three, single row, 50 foot
plots was sprayed with Faraquat (42% active) at a rate of 0.66 quarts plus Ortho
X-77 spreader at a rate of 5.3 ounces/100 gallons/A. Within nine days 95-100%
of the leaves and vines in the treated plots were brown and dead, while the foli-
age in the control plots was still green. When the tubers were harvested no
difference in yield, internal browning or skin set was observed between treated
and untreated potatoes.
During the 1967 potato season three potato defoliants will be compared. The
treatments will be; (1) Paraquat at 0.66 quarts plus Ortho X-77 spreader at 5
ounces/A. (2) Des-I-Cate (15% Endothall) at 2 and 4 gallons/A. (3) Sodium
arsenite at 8 Ibs/A and (4) Check no treatments.
- 12 -
INFLUENCE OF PLANTING AND HARVEST DATES ON
FIELD OF MULCHED AND UNMULCHED POTATOES
Planting Harvest Plastic
Date Date Unmulched Mulched
1965 3 Planting and 2 Harvest dates.
1/13 4/27 144 208
_____5/20 159 189
1/27 4/27 152 221
5/20 193 235
2/10 4/27 170 206
5/20 246 285
1966 2 Planting and 2 Harvest dates.
1/25 4/26 108 198
_5/17 184 260
- 13 -