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Vegetarian Newsletter 5
A Vegetable Crops Extension Publication
University
of Florida
Institute of Food and Agricultural Sciences
Cooperative Extension Service
- January 2000
- 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, clb@gnv.ifas.ufl.edu
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
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 goals.
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 comsumers. 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 strawberry.
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 ëPriorityí 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
www.imok.ufl.edu/veghort/liv.
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 ëone-stop
shoppingí 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 diseases.
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 western types.
Soil
type was an Orangeburg loamy fine sand. Soil pH prior to planting was 6.6.
Total fertilizer applied was 165-50-165 lb/a of N-P2O5-K2O.
Beds were fumigated with 350 lb/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 Duncanís 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 ëZodiací (western type) to a
low of 477 cwt/a for ëSME 7122ë (western type). There were 6 entries with
yields similar to ëZodiací. Average fruit size ranged from a low of 2.9
lbs for ëAllstarí to a high of 5.1 lbs for ëViennaí. Only ëSMX 7119' produced
fruit as large as ëViennaí. Soluble solids ranged from 13.9% for ëSMX 7204í
to 10.1 % for ëSME 7126'. No other entry had soluble solids as high as ëSMX
7204'. All eastern types had soluble solid levels above 11.0%. Flesh color
ranged from 4.0 for ëEclipseí to 2.0 for ëCruiserí.
|
Table 1. Total
yields, average fruit weight, soluble solids, and internal color
rating for cantaloupe replicated trial. NFREC Quincy, Spring 1999.
|
Entry
|
Yield cwt/A
|
Average
fruit weight (lbs)
|
Soluble
solids (%)
|
Flesh colorz
|
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
|
10.5 e
|
2.0 e
|
Allstar (W)
|
640 ab
|
2.9 e
|
11.2 c-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
|
Desert Princess
(W)
|
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
|
2.3 de
|
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 Duncanís Multiple Range
Test, 5% level.
|
(Olson,
Vegetarian 00-01)
Sanitizers for Vegetable Packinghouse Recirculated Water
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 sanitation.
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
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 (HOCl) 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 (ClO2)
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. ClO2 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, ClO2 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 ClO2,
some generators produce free chlorine that may form THMs and ClO2
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 (03)
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 µg/ml or 30 ppm at
20 oC), 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 ozoneís
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 sanitizer in packinghouse water systems.)
|
Broad spectrum
- effective on many different microbes.
|
Sensitive
to pH. Above or below 6.5 to 7.5 reduces activity or increases
noxious odors.
|
|
|
Practically
no residue left on the commodity.
|
Can form small
amounts of potentially carcinogenic compounds (e.g. trihalomethanes).
|
|
|
|
Can irritate
skin and damage mucous membranes.
|
Chlorine Dioxide
|
Has 2.5 times
the killing power of chlorine.
|
Must be generated
on-site.
|
|
|
Activity is
much less pH dependent than chlorine.
|
Greater human
exposure risk than chlorine. Off-gassing of noxious gases is common.
|
|
|
Does not form
trihalomethanes like chlorine.
|
Concentrated
gases can be explosive.
|
Peroxyacetic
acid
|
No known toxic
residues or byproducts.
|
Activity is
reduced in the presence of metal ions.
|
|
|
Produces very
little off-gassing.
|
Concentrated
product is very toxic to humans.
|
|
|
Less affected
by organic matter than chlorine.
|
Sensitive
to pH. Greatly reduced activity at pH above 7-8.
|
|
|
Low corrosiveness
to equipment.
|
|
Ozone
|
No known toxic
residues or byproducts.
|
Must be generated
on-site.
|
|
|
Can reduce
pesticide residues in the water.
|
Ozone gas
is toxic to humans. Off-gassing can be a problem.
|
|
|
Less sensitive
to pH than chlorine (but breaks down much faster above ~ pH 8.5).
|
Treated water
should be filtered to 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
|
1
|
Tomato
|
Better Boy
|
Blossom
drop and blossom-end rot (tie)
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(Stephens,
Vegetarian 00-01)
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Green - Seeds Co., Ltd.
81/10B Ho Van Hue Street, Phu Nhuan District, Ward 9, Ho Chi Minh City, Vietnam
Tel: +84 (8) 847 6901 - Fax: +84 (8) 844 1392 - Email: info@green-seeds.com
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