A Vegetable Crops Extension Publication
University of Florida
Institute of Food and Agricultural Sciences
Cooperative Extension Service
Adobe Acrobat .pdf
VEGETABLE CROPS CALENDAR
SOngoing Research at the GCREC-Dover
SSouth Florida Extension Leadership in Vegetables
*Cantaloupe Variety Trial Results Spring 1999. NFREC. Quincy. FL
* Sanitizers for Veaetable Packinahouse Recirculated Water
STop Ten Vegetables of the 20th Century
Vegetable Crops Calendar
Australian Vegetable Tour. January 7-10, 2000. Contact: Dr. Doug Sanders, NC State
University (919) 515-1222, E-mail: Doug Sanders(NCSU.edu
Suwannee Valley Field and Greenhouse Shortcourse and Trade Show. January 8, 2000.
Suwannee County Coliseum, Live Oak, FL. Contact: Bob Hochmuth (904) 362-1725.
Watermelon Production Meeting. Thursday, January 27, 2000, Marianna and Bonifay. Contact:
Charles Brasher, 850-482-9620. firstname.lastname@example.org (Click for AGENDA)
2000 Florida Postharvest Horticulture Institute and Industry Tour.
Institute March 6th, University of Florida, Gainesville, with video-links to several sites in Florida.
Industry Tour March 7-10th Statewide
For more information contact: Steve Sargent, (352) 392-1928 ext. 215, e-mail or Abbie Fox (352)
392-1928 ext.235, fax (352) 392-5653, e-mail
Commercial Vegetable Production
Ongoing Research at the GCREC-Dover
The center is located 15 miles east of Tampa, in the heart of Florida's
strawberry production area. While researchers at Dover have state wide
responsibility, 90% of the state's 6,000+ acres of strawberries are located within
20 miles of the center. The Strawberry Investigation Laboratory was opened in
1925 and moved to its current location in 1963. The Lab's focus is to develop and
expand knowledge and technology of strawberry production which will enable
Florida growers to remain competitive with other production areas in the U.S. and
abroad. Currently, there are 3 faculty members working to accomplish these
Dr. J.R. Duval is currently working to improve cultural practices and
understanding of strawberry physiology. Transplant type, transplant date, and
varietal influences on yielding pattern are being examined. It is hoped that this
research will equip growers to accurately plan their planting schedules to
maximize financial returns. Root geometry and mass are being looked at to
determine their effects on plant establishment and subsequent yields. Plant
growth regulators are being studied to determine the benefit of increased or
decreased vegetative growth. Manganese nutrition is being analyzed to
determine its role in the development of plant disease. Dr. Duval is also working
in conjunction with Eric Waldo of the Hillsborough County Extension office on
hydroponic field production of strawberries in perlite bags. In the future,
experimentation on methyl bromide alternatives, carbohydrate partitioning,
photosynthesis, transplant production, irrigation efficiency and nutrient
management are planned.
Strawberry breeding and genetics are the main focus of Dr. Craig Chandler's
research effort. To date, he has released two varieties 'Rosa Linda' and 'Sweet
Charlie'. 'Sweet Charlie' accounts for approximately 40% of all strawberries
grown in Florida. It is an anthracnose-resistant variety which produces early,
sweet flavorful fruit which are popular with consumers. Currently, Dr. Chandler
has two varieties ready for release which are tentatively named 'Earlibrite' and
'Strawberry Festival'. These varieties will provide Florida strawberry producers
better options than varieties developed elsewhere around the world.
Dr. Daniel Legard, a plant pathologist, is currently probing chemical and
cultural methods to reduce pesticides sprayed on strawberries (Florida
strawberries receive more applications of pesticides than any other food crop
grown in the U.S.). Particular interest is being paid to determine optimal control
strategies for botrytis fruit rot, anthracnose, powdery mildew, and gray mold of
In addition to Drs. Duval, Chandler and Legard, graduate students, post-docs,
visiting scientists and faculty members from other centers conduct research at
the station. In particular, Dr. James Price has implemented a research program
studying two-spot spider mites and Dr. Joe Noling is examining methods to cope
with the loss of methyl bromide. Collaborative efforts with foreign institutions are
being conducted at Dover as well.
(Duval, Vegetarian 00-01)
South Florida Extension Leadership in Vegetables
Because of the unique nature of vegetable production in South Florida, an
Extension Working Group was organized as a branch of State Major Program,
FL107 in June 1999 to help fill perceived needs for information by South Florida
growers. The South Florida Extension Leadership in Vegetables (LIV) working
group is spearheaded by Dr. Charles Vavrina with faculty participation from the
four Research and Education Centers in South Florida (EREC, IRREC,
SWFREC, and TREC) and Dade, Hendry, Hillsborough, Manatee and Palm
Beach counties. A small group of growers are involved to provide a producer
point of view. County Advisory Committees formulated 'Priority' lists which were
used to identify the topics most commonly cited as requiring information and
these issues are being addressed by four subcommittees; Communication,
Cultural Practices, Integrated Pest Management, and Production Economics.
Each subcommittee has developed an Action Plan of the methods that they will
use to address the information gaps, with appropriate deadlines and deliverables
indicated. One of the first products of LIV was the website developed by Dr.
Vavrina. Action plans and current updates on the work of the LIV can be found at
On November 30, 1999, the working group met to discuss the
accomplishments of each subcommittee and to reassess priorities and methods.
The Communication Subcommittee has as its focus the improvement of
communication among the personnel currently working in vegetable extension in
South Florida and the compilation of existing information relevant to South
Florida vegetable production. One or more e-mail list-serves will be developed to
facilitate the exchange of information among extension personnel in South
Florida. Additional links will be added to the LIV website to create a 'one-stop
shopping' method of accessing a range of newsletters and information sources.
Focus areas of the Cultural Practices Subcommittee include 1) determining the
cost of compliance with environmental regulations, 2) assessing crop pesticide
choices, 3) evaluating methyl bromide alternatives, in particular composting and
cover crops, 4) assessing vegetable irrigation scheduling and 5) evaluating
fertilizer application methods.
The focus of the Integrated Pest Management Subcommittee is information
relevant to the utilization and evaluation of biocontrol agents. The committee has
developed an annotated list of IFAS personnel with expertise in biological and
biorational control of insects and mites in vegetable crops as well as identifying
sources of information on the use of biological agents for the control of plant
The Production Economics Subcommittee is working in the areas of enterprise
budgets and labor demographics. The list of crops for which enterprise budgets
will be developed is based on agent requests. This committee has also compiled
a web-based listing of available budget information from throughout the US on
over 40 crops including specialty vegetables, herbs and organically produced
vegetables, which is available on the LIV website.
It is the intent of the LIV working group that as one priority issue is addressed
a new one will take its place. Through the efforts of the LIV working group, the
links between the County Advisory Committees, county faculty, extension
specialists, researchers and research centers in south Florida will be
strengthened and the imperatives and initiatives of Florida FIRST will be met.
(Lamb, Vegetarian 00-01)
Cantaloupe Variety Trial Results Spring 1999,
NFREC, Quincy, FL
Cantaloupes are a minor crop in Florida with much of the production sold
through roadside stands and local markets. The biggest problem with cantaloupe
production in Florida is the ability to produce a high quality fruit that has sufficient
keeping ability so that it can pass through the market chain. Most of the varieties
used at this time are eastern types with prominent sutures, medium netting but
do not have a long shelf life. Western types which are usually round, smaller,
nearly sutureless, and have a longer shelf life but have not been grown much in
Florida due to lower yields and lack of disease resistance.
This trial was part of a statewide trial to evaluate varieties at multiple locations.
The purpose of this trial was to evaluate varieties for adaptability to the
panhandle area of the state. Included in the trial were 5 eastern types and 9
Soil type was an Orangeburg loamy fine sand. Soil pH prior to planting was
6.6. Total fertilizer applied was 165-50-165 Ib/a of N-P205-K20. Beds were
fumigated with 350 Ib/a of methyl bromide:chloropicrin (67:33) prior to application
of black polyethylene mulch. Irrigation was with a single drip tube (Chapin Twin
Wall IV, 0.5 gpm/100ft at 10 psi) buried 1-inch deep, 6 inches off center.
Between-row spacing was 6 feet and in-row spacing was 20 inches (4356
plants/a). Plot length was 34 feet. First and last plants in plot were honey dews to
help separate plots.
Fourteen entries were seeded on 18 Feb, 1999, into flats with cell size 1.5 in.
X 1.5 in. X 2.5 in. Plots were planted on 22 March, 1999. Four replications were
used. Between-row weed control was accomplished with Curbit pretransplant
and post-directed applications of Gramoxone. Pesticides were applied as needed
to control pests.
Seven harvests were made from 1 June to 21 June 1999. Marketable fruit
were weighed and counted at each harvest. Soluble solid determinations were
made with a digital refractometer on two fruit on the 7 June harvest. Ratings of 1
to 5 were also made on flesh color with 5 being intense orange color and 1 being
pale orange. The resulting data were subjected to analysis of variance and
means were separated by Duncan's Multiple Range Test, 5% level.
Temperatures during production period were near normal but very dry. Spider
mites came in later and were very difficult to control.
Total yields ranged from a high of 726 cwt/a for 'Zodiac' (western type) to a
low of 477 cwt/a for 'SME 7122' (western type). There were 6 entries with yields
similar to 'Zodiac'. Average fruit size ranged from a low of 2.9 Ibs for 'Allstar' to a
high of 5.1 Ibs for 'Vienna'. Only 'SMX 7119' produced fruit as large as 'Vienna'.
Soluble solids ranged from 13.9% for 'SMX 7204' to 10.1 % for 'SME 7126'. No
other entry had soluble solids as high as 'SMX 7204'. All eastern types had
soluble solid levels above 11.0%. Flesh color ranged from 4.0 for 'Eclipse' to 2.0
Table 1. Total yields, average fruit weight, soluble solids, and internal color
rating for cantaloupe replicated trial. NFREC Quincy, Spring 1999.
Yield Average fruit Soluble Flesh
Entry cwt/A weight (Ibs) solids (%) color
Zodiac (W)y 726 ax 3.5 cd 11.1 c-e 2.3 de
SMX 7119 (E) 717 a 5.0 a 12.3 bc 3.5 ab
SMX 7204 (W) 668 ab 3.2 de 13.9 a 3.4 ab
Cruiser (W) 647 ab 3.0 e 10.5e 2.0 e
Allstar (W) 640 ab 2.9 e 11.2c-e 2.5 c-e
Athena (E) 618 a-c 3.8 bc 12.5 b 2.3 de
Eclipse (E) 617 a-c 4.1 b 12.4 b 4.0 a
SP 599 bc 3.0 e 10.4 e 3.5 ab
Vienna (E) 586 b-d 5.1 a 11.0 de 3.8 ab
SME 7126(W) 580 b-d 4.0 bc 10.1 e 2.3de
Desert Queen (W) 521 cd 3.0 e 11.9 b-d 2.5 c-e
SME 7124 (W) 518 cd 3.7 bc 11.0 de 3.3 a-c
Cordele (E) 501 cd 3.9 bc 11.0 de 3.0 b-d
SME 7122 (W) 477 d 3.6 b-d 10.6 de 2.3 de
z Rating 1-5 with 1 being pale orange and 5 being intense orange.
Y W = western type and E = eastern type.
x Mean separation in columns by Duncan's Multiple Range Test, 5% level.
(Olson, Vegetarian 00-01)
Sanitizers for Vegetable Packinghouse
Proper sanitation of water (especially recirculated water) used in dump tanks,
hydrocoolers, etc. of fresh vegetable packinghouses is important for delivering
sound produce to the consumer. Not only do unsanitary conditions promote
direct product loss through decay, but rising food safety concerns about human
pathogens are becoming increasingly important to consumers. Because water is
one of the best carriers of pathogens, it must be treated (either chemically or
physically) to prevent the accumulation of pathogens in the water and prevent
cross-contamination of sound produce. Such treatments are not particularly
effective at reducing pathogen levels already on the surface of produce; it is
much more effective to prevent contamination in the first place. This means
following Good Agricultural Practices regarding water quality, use of manure and
municipal biosolids, harvesting practices, and worker, field and packing facility
Although chlorine is currently the sanitizer of choice for most vegetable
packinghouses, other chemicals have been approved by the EPA for contact with
food products. This article will briefly list some of the approved antimicrobial
chemicals and discuss advantages and disadvantages of using each (Table 1).
Chlorine is currently the predominant method used by packinghouses to
sanitize water systems. Although chlorine is available in three forms sodium
hypochlorite, calcium hypochlorite, or chlorine gas it is the resulting
hypochlorous acid (HOCI) that is primarily responsible for killing pathogens.
Currently, IFAS recommends using 100 to 150 parts per million (ppm) of free
chlorine with a water pH between 6.5 and 7.5.
The main advantages to using chlorine are that it is effective at killing a broad
range of pathogens and that it is relatively inexpensive. It also leaves very little
residue or film on surfaces. However, chlorine is corrosive to equipment and
water pH must be monitored and adjusted often to maintain chlorine in its active
form. Continual addition of chlorine without changing the water can result in the
accumulation of high salt concentrations that may injure some products. Further,
chlorine can react with organic matter to form small amounts of different
trihalomethanes (THMs) that are thought to be carcinogenic. However, the
relative risks from chlorine-generated THMs on the surface of fresh horticultural
produce is extremely low.
Chlorine dioxide (C102)
Chlorine dioxide is a synthetically produced yellowish-green gas with an odor
like chlorine but with 2.5 times the oxidizing power of chlorine. This higher
potency translates into less chemical required for the same sanitizing effects
compared to chlorine. C102 is typically used at concentrations between 1 and 5
ppm. However, it usually must be generated on-site because the concentrated
gas can be explosive and decomposes rapidly when exposed to light or
temperatures above 50 OC (122 OF). These concentrated gases also poses a
greater risk to workers than sodium or calcium hypochlorite. Noxious odors from
off-gassing can be a common problem, especially at higher concentrations,
which restricts its use to well-ventilated areas away from workers. Unlike
chlorine, C102 does not hydrolyze in water and is virtually unaffected by pH
changes between 6 to 10 and does not react with organic matter to form THMs.
However, in addition to C102, some generators produce free chlorine that may
form THMs and C102 may produce other potentially hazardous byproducts (e.g.
chlorate and chlorite). One additional drawback is that simple assays to monitor
chlorine dioxide concentration are currently not available.
Peroxyacetic Acid (PAA)
Peroxyacetic acid is a strong oxidizer formed from hydrogen peroxide and
acetic acid. The concentrated product (40% PAA) has a pungent odor and is
highly toxic to humans. PAA is very soluble in water with very little off-gassing
and it leaves no known toxic breakdown products or residue on the produce.
Unlike chlorine and ozone, it has good stability in water containing organic
matter, which can greatly increase the longevity of the sanitizer, and it is not
particularly corrosive to equipment. PAA is most active in acidic environments
with pH between 3.5 and 7, but activity declines rapidly at pHs above 7-8. High
temperatures and metal ion contamination will also reduce its activity.
Ozone gas is one of the strongest oxidizing agents and sanitizers available. An
expert panel declared ozone to be Generally Recognized As Safe (GRAS) in
1997 and ozone is currently legal for food contact applications. Although ozone is
not particularly soluble in water (30 pg/ml or 30 ppm at 20 C), concentrations as
low as 0.5 to 2 ppm are effective against pathogens in clean water with no soil or
organic matter. In practice, even concentrations of 10 ppm are difficult to obtain
and concentrations of 5 ppm are more common.
Ozone decomposes quickly in water with a half-life of 15 to 20 minutes in
clean water but less than a minute in water containing suspended soil particles
and organic matter. Thus, ozonated water should be filtered to remove these
particulates. The cooler temperatures of hydrocoolers may also extend ozone's
half-life. The antimicrobial activity of ozone is stable between pH 6 and 8 but
decomposes more rapidly at higher pHs. Ozone breaks down to oxygen and no
other toxic by-products have been reported.
Because of its strong oxidizing potential, ozone is toxic to humans and must
be generated on-site. Prolonged exposure to more than 4 ppm ozone can be
lethal. Ozone has a pungent odor that can be detected by humans at 0.01 to 0.04
ppm. OSHA has set worker safety limits of 0.1 ppm exposure over an 8 hour
period and 0.3 ppm over a 15 minute period. At concentrations in water above 1
ppm, off-gassing can result in concentrations in the air that exceed OSHA limits
of 0.1 ppm. Another disadvantage of using ozone is that it is highly corrosive to
equipment, including rubber and some plastics.
Table 1. Sanitizing chemicals for packinghouses.
Compound Advantages Disadvantages
Chlorine Relatively inexpensive. Corrosive to equipment.
(Most widely used Sensitive to pH. Above or below 6.5 to 7.5
sanitizer in Broad spectrum effective reduces activity or increases noxious
reduces activity or increases noxious
packinghouse water on many different microbes. odors.
Can form small amounts of potentially
Practically no residue left on carcinogenic compounds (e.g.
the commodity, carcinogenic compounds (e.g.
Can irritate skin and damage mucous
Has 2.5 times the killing
Chlorine Dioxide Has 2.5 times the killing Must be generated on-site.
power of chlorine.
Activity is much less pH Greater human exposure risk than
dependent than chlorine. chlorine. Off-gassing of noxious gases is
Does not form
trihalomethanes like Concentrated gases can be explosive.
No known toxic residues or Activity is reduced in the presence of
Peroxyacetic ac byproducts metal ions.
Produces very little off- Concentrated product is very toxic to
Less affected by organic Sensitive to pH. Greatly reduced activity
matter than chlorine, at pH above 7-8.
Low corrosiveness to
No known toxic residues or
Ozone byproducts. Must be generated on-site.
Can reduce pesticide Ozone gas is toxic to humans. Off-
residues in the water. gassing can be a problem.
Less sensitive to pH than
chlorine (but breaks down Treated water should be filtered to
much faster above ~ pH remove particulates and organic matter.
Very corrosive to equipment (including
rubber and some plastics).
Highly unstable in water half life ~ 15
minutes; may be less than one minute in
water with organic matter or soil.
Note: Although Quaternary Ammonia is an effective sanitizer with useful properties and can be
used to sanitize equipment, it is not registered for contact with food.
(Ritenour, Sargent and Brecht, Vegetarian 00-01)
Top Ten Vegetables of the 20th Century
Just about everyone has their list of top tens of athletes, movies, actors,
news stories, or whatever. So I thought I would compose a list of the top ten
vegetables that have been the most popular or important to vegetable gardeners
in Florida over the past 100 years. Please bear in mind that my career as
Extension vegetable specialist covers only 38 years of that period, however, I am
looking at old gardening records, especially during the thirties through fifties.
First, I will list the 10 most important crops. It seems customary to begin with
the 10th on the list, then build toward Number One. I guess anyone could make a
case for almost any one of these as their all-time favorites, or add some not on
my list. Anyway, here goes.
Table 1. Top-ten vegetables for the 20th century.
Rank Vegetable Leading variety Worst problem
10 Collard Georgia strains Leaf-feeding larvae
9 Pepper Early Calwonder Mosaaic virus
8 Lettuce Great Lakes Climatic stress
7 Peas, Southern California Blackeye Cowpea curculio
6 Radish, summer Early Scarlet Globe Poor root formation
5 Squash, summer Summer Crookneck Poor fruit set
4 Cucumber Poinsett Downy mildew
3 Corn, sweet Silver Queen Corn earworm
2 Potato, Irish Sebago Seed-piece rot
Tomato Better Boy Blossom drop and
blossom-end rot (tie)
(Stephens, Vegetarian 00-01)
Extension Vegetable Crops Specialists
Daniel J. Cantliffe
Professor and Chairman, Horticultural Sciences
Timothy E. Crocker
Professor, deciduous fruits and nuts, strawberry
Assistant Professor, strawberry
Betsy M. Lamb
Assistant Professor, production
Assistant Professor, soils
Donald N. Maynard
Stephen M. Olson
Professor, small farms
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Mark A. Ritenour
Ronald W. Rice
Assistant Professor, nutrition
Steven A. Sargent
Professor and Editor,
William M. Stall
Professor, weed control
James M. Stephens
Charles S. Vavrina
James M. White
Associate Professor, organic
have any questions or