INSTITUTE OF FOOD AND
UNIVERSITY OF FLORIDA
A Vegetable Crops Extension Publication
Vegetable Crops Department *1255 lHSPP Gainesville. FL 32611* Telephone 392-213.
November 16, 1987
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
B. New Publications.
II. PESTICIDE UPDATE
A. Section 18 for the Use of Fusilade on Celery
and Head Lettuce.
B. Nightshade Control Reduction With Paraquat Due
to Copper Fungicide Antagonism.
III. COMMERCIAL VEGETABLES
A. 1987 Leek Variety Trial Results.
B. Use of Tensiometers in Vegetable Production.
IV. VEGETABLE GARDENING
A. Miniature Pumpkins.
Note: Anyone is free to use the information in this
newsletter. Whenever possible, please give credit to the
The use of trade names in this publication is solely for
the purpose of providing information and does not
necessarily constitute a recommendation of the product.
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research,
educational information and other services only to individuals and institutions that function without regard to race, color, sex. or national origin.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS, STATE OF FLORIDA, IFAS, UNIVERSITY OF
FLORIDA, U. S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING
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I. NOTES OF INTERESTS
A. Vegetable Crops Calendar
November 3-5, 1987. FSHS Convention.
Orlando Hyatt Hotel.
November 6, 1987. ASHS Tours. Or-
lando Hyatt Hotel.
November 8-12, 1987. ASHS Convention.
Orlando Hyatt Hotel.
November 19, 1987. 9:00 am 3:30 pm
Tenth Annual Conference for Vegetable
Technical and Sales Reps. Kendrick
Auditorium, Manatee Co. Ext. Office,
1303 17 Street, Palmetto. (Contact
Phyllis Gilreath (813) 722-4524.)
November 30 December 2, 1987. USDA
Vegetable Collaborators' Conference.
Omni Hotel, Charleston, SC (Contact
December 7-11, 1987. Vegetable Crops
Departmental Review. University of
B. New Publications.
Tomato Variety Trial Results for
Spring 1987. Bradenton GCREC Re-
search Rept. BRA1987-20 by T.K. Howe,
J.W. Scott, and W.E. Waters.
Recent Advances in Managing the
Sweetpotato Whitefly on Poinsettia.
BRA 1987-21, by J.F. Price, D.J.
Schuster and D.E. Short.
Cucurbit Variety Evaluation,
1987. Leesburg CFREC Research Rept.
LBG 87-4 by G.W. Elmstrom.
To request the publications,
please contact authors directly.
A. Section 18 for the Use of
Fusilade on Celery and Head Lettuce.
The Environmental Protection
Agency (EPA) has granted a Section 18
specific exemption to the Florida
Department of Agriculture and
Consumer Services for the use of
fluazifop-p-butyl (Fusilade 2000) on
celery and head lettuce to control
emerged goosegrass, crabgrass, bermu-
dagrass, foxtails, panicums, and
A maximum of 2 ground applica-
tions at a maximum rate of 0.188 lb
ai/A may be made to celery.
A single ground application of
0.188 lb ai/A may be made to head
Applications will not be made
within 30 days of harvest. Field
flooding may not be made 45-60 days
after last application. The exemp-
tion expires July 31, 1988. Read and
follow all label directions and
(Stall: Vegetarian 87-11)
Nightshade Control Reduction
With Paraquat Due to Copper Fungicide
For several years, growers in
the southwest Florida production area
have reported what they believed to
be the development of resistance to
paraquat by nightshade plants. Di-
rected, shielded paraquat applica-
tions did not fully control the
nightshade. Those that were not
controlled were primarily found along
the edge of the plastic mulch. It
was first thought that these night-
shade plants had not been sprayed or
that the coverage of paraquat that
they recieved was lower than what was
delivered to the middles due to
nozzle arrangements. When these
plants were covered with a full rate
of paraquat by hand held backpack
II. PESTICIDE UPDATE
sprayers, they were not fully con-
At the Gulf Coast Research and
Education Center, Bradenton, Dr. Jim
Gilreath found that paraquat still
controlled nightshade in his experi-
While wondering if there was
truly a resistance established in the
southwest Florida area, we observed
that the weeds along the sides of the
beds were being covered with fungi-
cides, and the copper in the mix was
building up on the plant leaves.
Reggie Brown, Collier County
Extension Director harvested two
large batches of nightshade berries
from old fields. We extracted the
seed from these fruit and grew
several batches of plants out in
Gainesville to try to determine if
the copper fungicides was inhibiting
action of the paraquat.
In the experiments we divided
the plants and sprayed no copper
fungicides, copper fungicides 3 times
in 1 week and 6 times in 2 weeks on
the nightshade plants. These plants
were divided and paraquat was sprayed
at 1/2 rate and full rate on each of
the copper treatments.
The results were when no copper
was sprayed on the nightshade plants,
both the 1/2 and full rate of para-
quat killed the plants. When 1 week
of copper was sprayed on the plants,
the stems collapsed in the upper
portion of the plants, but resprout-
ed. Regrowth from the plants treated
for 2 weeks with copper was primarily
new leaf formation. Very little stem
kill was seen.
This experiment shows a definite
antagonism between paraquat and
copper fungicides when sprayed on the
nightshade plants. The more copper
on the plants, the less control
obtained from paraquat.
We have also noted that younger
nightshade plants are controlled to a
greater extent than older plants,
even with copper sprays.
The experiments are still on-
going to find a mechanism to overcome
(Stall: Vegetarian 87-11)
III. COMMERCIAL VEGETABLES
A. 1987 Leek Variety Trial
Commercial production of leeks
(Allium ampeloprasum, Porrum Group)
is small in Florida at the present
time. However, it appears that there
is potential for more production
based on consumer interest. The
Packer's recent profile of fresh
produce consumers showed that of 30
specialty crops, 38% of the respon-
dents had tried leeks, and another
48% indicated that they had heard of
Leeks are considered a major
vegetable crop in Europe rather than
a specialty crop as they are in the
United States. For example, the leek
crop in the United Kingdom in 1985
was about 50,000 tons and had an
approximate value exceeding $26
Leeks, a long-season crop, are
grown for their swollen, but not
bulbed, leaf base, the edible portion
is the shank whick extends from the
stem plate to the base of the first
aerial leaf. A white shank is
required for the market so blanching
with soil or straw, for polyethylene-
mulched crops, is required. Because
of the necessity of blanching, the
crop is probably better suited to
open-ground culture than to mulched
culture. Leeks are not as pungent as
onions, and are prized for their
delicate flavor. The crop can be
direct-seeded, but stand establish-
ment from transplants is probably
more desirable. Leeks are very cold
tolerant and a succession of plant-
ings should provide a continuous
supply from late fall through mid-
spring in Central Florida.
Leek yields ranged from 3,391 lb
for 'Carina' to 5,571 lb for 'Varna'
per 1000 lbf. Yields of 'Kazan',
'8240', 'Albana', 'Kilima', and
'Otina' were not statistically dif-
ferent from those of 'Varna', the
highest yielding variety. All of the
other varieties produced yields that
were not significantly different from
'Carina' the lowest yielding variety.
Weight of individual leeks
ranged from 9.4 oz for 'Carina' to
14.9 oz for 'Varna'. Since there was
no difference among the varieties in
plant stand, total yield was related
directly to individual plant weight.
Plant height, measured from the
stem plate to the tip of the longest
leaf, ranged from 33.9 in. for
'Electra' to 52.3 in. for 'Varna'.
Shank length is one of the most
important characteristics in leeks.
'Varna' produced 10.5 in. long
shanks, which may be too long for
many markets. The shortest shanks
were produced by 'Conqueror' at 3.2
inches. Most varieties produced
shanks that were in the highly
acceptable range of 3.5 to 6 in.
long. Shank diameter did not vary
greatly among the varieties, and
ranged from 1.0 to 1.5 in. Most
varieties had 1.2 to 1.4 in. diameter
shanks. As would be expected from
the foregoing, 'Varna' had the
highest shank length:diameter ratio.
Leek leaves typically have an
equitant arrangement, i.e., leaves
are overlapping in two ranks. When
fully expressed, the leaves will be
flat in a fan-like arrangement. This
should be considered an advantage to
facilitate bunching. Some varieties
in this trial deviated from the
fully equitant arrangement: 'Varna',
'Kazan', '8240', 'Otina', 'Argenta',
'Electra', 'Catalina', 'Armor', and
'Carina' were medium flat whereas
'Varina' and 'Conqueror' were thick
Observations were made on the
tendency of these varieties to bulb.
Any deviation from a parallel shank
was noted, however slight. Only
'Kilima' showed a marked tendency to
bulb; it is uncertain if this would
have affected marketability of the
Leeks are a long season crop.
In this trial, 70 days were required
from seeding to transplant and 112
days elapsed between transplanting
and initial harvest. Production time
would likely be somewhat shorter for
spring and fall crops. The yield
potential for leeks with two rows per
bed on 4.5 ft. centers is high -
53,927 lb for 9680 lbf.
See GCREC Res. Rept. BRA1987-17
for a complete report of these
(Maynard: Vegetarian 87-11)
B. Use of Tensiometers in Vege-
Efficient irrigation practices
are very important in reducing
farming costs and conserving natural
resources. To be efficient irriga-
tion managers, we must be able to
predict water needs of our crops, and
then apply the water in measured
fashion. One tool, mentioned in the
October Guidelines, for irrigation
scheduling is the tensiometer.
The tensiometer is a simple
instrument that indirectly measures
the amount of water in the soil. The
instrument consists of a porous,
ceramic cup connected to a vacuum
gauge through a long, rigid tube
(Figure 1). Available at most irriga-
tion supply companies, the tensiomet-
er costs about $30 to $40 depending
on length needed.
Installation. Before placing in
the field, the tensiometer must be
readied by filling the tube with
water and allowing it to stand
vertically in a bucket of water to
soak the ceramic tip. A hand vacuum
pump should then be used to remove
air bubbles from the tensiometer
gauge. The pump, purchased with the
tensiometer, is placed over the open
end of the tensiometer tube and the
air bubbles are pumped out. After
pumping, top-off the water in the
tube and replace the cap.
Choose a site in the field that
is representative of that field or is
representative of the irrigation
management unit or zone. Avoid wet
or dry areas. Place the tensiometers
within the plant canopy in such'a
manner that it is not shielded from
rain or irrigation, nor is it subject
Depth of placement is important.
Place the tensiometer in the field so
that the ceramic cup is in the zone
of active roots. For many shallow-
rooted vegetables, only one tensio-
meter with the ceramic cup in the 6
to 12-inch depth is needed. For
moderately deep roots, two tensiomet-
ers may be needed at each site, one
tensiometer placed deeper than the
Use a tensiometer soil coring
instrument to create a cylindrical
hole in which to place the tensiomet-
er. Push the tensiometer into the
hole to the correct depth, and
lightly tamp the surface soil to seal
the instrument. A short period will
be required for the correct reading
to be established.
How it works. The tensiometer
measures "soil moisture tension". As
the soil dries out, water is pulled
from the tube through the ceramic
tip. This creates a tension or
vacuum inside the tube which is
measured by the vacuum gauge. After
a rain or irrigation, water from the
soil moves into the tube reducing the
vacuum. If the soil becomes too dry,
air can move into the system and the
instrument will not function.
The units of measurement and the
gauge are called centibars and are a
measurement of soil moisture tension.
Since we are really measuring a
vacuum, the units are really negative
but the minus sign is usually omitted
on the gauge.
Irrigation scheduling. Tensio-
meters help decide when to irrigate,
but they do not tell how much water
to apply. Depending on your soil
type, different readings will indi-
cate when to irrigate. For sandy
soils in Florida, this critical value
is in the range of 12 to 20 centibars
but on heavier soils the critical
value might be 60.
To determine the amount of water
to apply, a moisture characteristic
curve for your soil type must be
used. Your extension agent or farm
advisor can help with this problem.
The soil moisture curve will help
tell you how much water needs to be
applied to return the tensiometer to
the optimum reading for your soil and
If you have the needed infor-
mation as described above, the tens-
iometer can be used to automate
irrigations. The vacuum gauge can be
fitted with a switch so that the
irrigation system can be turned on
and off to pre-set gauge readings.
Tensiometer service. Periodic
field service will be needed to keep
the tensiometer operating properly.
This is usually because of air being
trapped in the tube. The tube should
be checked regularly for air and
topped off with more water if more
than one-half inch of air accumu-
lates. In dry soils, this might be a
Tensiometers are fragile instru-
ments and should be handled with care.
Be sure not to leave filled with
water under freezing conditions.
Summary. Tensiometers can be a
useful tool with which to schedule
irrigations, especially when the
system can be automated. Their
proper use involves a little initial
work to determine the moisture
characteristic curve, but there are
specialists that can help with this.
With proper installation and mainte-
nance, they will continuously measure
water potential and help you become
an efficient irrigation manager.
Smajstrla, A.G., D.S. Harrison, and
F.X. Duran. 1985. Tensiometers for
soil moisture measurement and irriga-
tion scheduling. Univ. Fla. Coop.
Ext. Circ. 487.
(Hochmuth: Vegetarian 87-11)
IV. VEGETABLE GARDENING
A. Miniature Pumpkins.
Miniature vegetables of all
types have been getting more and more
popular with both gardeners and
consumers over the past few years.
One that has become very prominent,
especially around Halloween and
Thanksgiving, is the miniature
This small, round, flat, orange
pumpkin resembles its larger rela-
tive, the Jack-O-Lantern pumpkin, but
is much smaller, seldom reaching more
than 6 ounces in weight, 3 to 4
inches in diameter, and 2 to 3 inches
Some so-called mini-pumpkins are
actually baby-sized regular pumpkins.
For example, one named 'Little Lan-
tern' weighs 1.9 lbs. and measures 5
inches wide by 4 inches high (Stokes
Seed Company), and another named
'Baby Pam' is 5 1/2 inches across
(Gurney Seed Company).
While there may be several more
varieties of the mini-type, a few of
today's more common ones are: 'Munch-
kin', a 3-4 inch diameter version
sold by Moran Seed Company; 'Sweetie-
Pie', measuring 3 inches wide, 1 3/4
inches high, and 5 ounces (Stokes
Seed Company); 'Bushkin', once sold
by Burpee Seed Company but recently
removed from sales for further selec-
tion work; 'Jack-Be-Little', by Parks
Seed Company, advertised as 2 inches
high and 3 inches in diameter; and
'Mini-Jack', offered by Gurney Seed
Two common questions are fre-
quently asked by gardeners and con-
sumers alike; what kind of vegetable
are these newcomers, pumpkins, gourds
or what, and are they edible?
Well, the little orange fruits
sure do look like pumpkins, but they
are hard and not very palatable,
resembling the gaily-colored orna-
mental apple and pear gourds. Both
regular jack-o-lantern type pumpkins
and the ornamental gourds belong to
the same genus and species, Cucurbita
pepo. One is called a pumpkin because
of its soft tender edible flesh,
while the other is called a gourd
because it becomes hardened rather
quickly and is generally considered
to be inedible. Okay, so now we have
the mini-pumpkins, which belong to
this same species, which are soft at
first but which become hard and
unpalatable rather quickly. Still
they are true pumpkins, but have the
most value as an ornamental gourd.
Let's just call them ornamental mini-
They grow on a rather short
trailing vine, where they are quite
prolific under Florida conditions.
Unlike regular pumpkins which produce
only a few fruits per plant, there
may be a dozen or more mini-pumpkins
on the vine. Of course, since these
cross readily with other Cucurbita
pepo members, it is not uncommon to
find a variety of off-type fruits in
While the mini-pumpkin could be
eaten safely when still immature
(non-hardened), by the time most
consumers purchase them, the fruits
are already too tough and hardened to
be palatable. For decorative effect,
painted or plain, the little mini-
pumpkin appears to be around for a
long time helping us enjoy Halloween
and Thanksgiving even more.
(Stephens: Vegetarian 87-11)
Prepared by Extension Vegetable Crops Specialists
Dr. D.J. Cantliffe
Dr. G.J. Hochmuth
Dr. W.M. Stall
Dr. D.D. Gull
Dr. D.N. Maynard
Mr. J.M. Ftephens